Add m-esr52 at 52.6.0

26 files changed, 7081 insertions, 0 deletions

diff --git a/dom/fetch/ChannelInfo.cpp b/dom/fetch/ChannelInfo.cpp
new file mode 100644
index 0000000000..5ecc7f7624
--- /dev/null
+++ b/dom/fetch/ChannelInfo.cpp
@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/ChannelInfo.h"
+#include "nsCOMPtr.h"
+#include "nsContentUtils.h"
+#include "nsIChannel.h"
+#include "nsIDocument.h"
+#include "nsIHttpChannel.h"
+#include "nsSerializationHelper.h"
+#include "mozilla/net/HttpBaseChannel.h"
+#include "mozilla/ipc/ChannelInfo.h"
+#include "nsNetUtil.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+void
+ChannelInfo::InitFromDocument(nsIDocument* aDoc)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mInited, "Cannot initialize the object twice");
+
+  nsCOMPtr<nsISupports> securityInfo = aDoc->GetSecurityInfo();
+  if (securityInfo) {
+    SetSecurityInfo(securityInfo);
+  }
+
+  mInited = true;
+}
+
+void
+ChannelInfo::InitFromChannel(nsIChannel* aChannel)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mInited, "Cannot initialize the object twice");
+
+  nsCOMPtr<nsISupports> securityInfo;
+  aChannel->GetSecurityInfo(getter_AddRefs(securityInfo));
+  if (securityInfo) {
+    SetSecurityInfo(securityInfo);
+  }
+
+  mInited = true;
+}
+
+void
+ChannelInfo::InitFromChromeGlobal(nsIGlobalObject* aGlobal)
+{
+  MOZ_ASSERT(!mInited, "Cannot initialize the object twice");
+  MOZ_ASSERT(aGlobal);
+
+  MOZ_RELEASE_ASSERT(
+    nsContentUtils::IsSystemPrincipal(aGlobal->PrincipalOrNull()));
+
+  mSecurityInfo.Truncate();
+  mInited = true;
+}
+
+void
+ChannelInfo::InitFromIPCChannelInfo(const mozilla::ipc::IPCChannelInfo& aChannelInfo)
+{
+  MOZ_ASSERT(!mInited, "Cannot initialize the object twice");
+
+  mSecurityInfo = aChannelInfo.securityInfo();
+
+  mInited = true;
+}
+
+void
+ChannelInfo::SetSecurityInfo(nsISupports* aSecurityInfo)
+{
+  MOZ_ASSERT(mSecurityInfo.IsEmpty(), "security info should only be set once");
+  nsCOMPtr<nsISerializable> serializable = do_QueryInterface(aSecurityInfo);
+  if (!serializable) {
+    NS_WARNING("A non-serializable object was passed to InternalResponse::SetSecurityInfo");
+    return;
+  }
+  NS_SerializeToString(serializable, mSecurityInfo);
+}
+
+nsresult
+ChannelInfo::ResurrectInfoOnChannel(nsIChannel* aChannel)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mInited);
+
+  if (!mSecurityInfo.IsEmpty()) {
+    nsCOMPtr<nsISupports> infoObj;
+    nsresult rv = NS_DeserializeObject(mSecurityInfo, getter_AddRefs(infoObj));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+    nsCOMPtr<nsIHttpChannel> httpChannel =
+      do_QueryInterface(aChannel);
+    MOZ_ASSERT(httpChannel);
+    net::HttpBaseChannel* httpBaseChannel =
+      static_cast<net::HttpBaseChannel*>(httpChannel.get());
+    rv = httpBaseChannel->OverrideSecurityInfo(infoObj);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  return NS_OK;
+}
+
+mozilla::ipc::IPCChannelInfo
+ChannelInfo::AsIPCChannelInfo() const
+{
+  // This may be called when mInited is false, for example if we try to store
+  // a synthesized Response object into the Cache.  Uninitialized and empty
+  // ChannelInfo objects are indistinguishable at the IPC level, so this is
+  // fine.
+
+  IPCChannelInfo ipcInfo;
+
+  ipcInfo.securityInfo() = mSecurityInfo;
+
+  return ipcInfo;
+}
diff --git a/dom/fetch/ChannelInfo.h b/dom/fetch/ChannelInfo.h
new file mode 100644
index 0000000000..a8acacfe09
--- /dev/null
+++ b/dom/fetch/ChannelInfo.h
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ChannelInfo_h
+#define mozilla_dom_ChannelInfo_h
+
+#include "nsString.h"
+#include "nsCOMPtr.h"
+
+class nsIChannel;
+class nsIDocument;
+class nsIGlobalObject;
+class nsIURI;
+
+namespace mozilla {
+namespace ipc {
+class IPCChannelInfo;
+} // namespace ipc
+
+namespace dom {
+
+// This class represents the information related to a Response that we
+// retrieve from the corresponding channel that is used to perform the fetch.
+//
+// When adding new members to this object, the following code needs to be
+// updated:
+// * IPCChannelInfo
+// * InitFromChannel and InitFromIPCChannelInfo members
+// * ResurrectInfoOnChannel member
+// * AsIPCChannelInfo member
+// * constructors and assignment operators for this class.
+// * DOM Cache schema code (in dom/cache/DBSchema.cpp) to ensure that the newly
+//   added member is saved into the DB and loaded from it properly.
+//
+// Care must be taken when initializing this object, or when calling
+// ResurrectInfoOnChannel().  This object cannot be initialized twice, and
+// ResurrectInfoOnChannel() cannot be called on it before it has been
+// initialized.  There are assertions ensuring these invariants.
+class ChannelInfo final
+{
+public:
+  typedef mozilla::ipc::IPCChannelInfo IPCChannelInfo;
+
+  ChannelInfo()
+    : mInited(false)
+  {
+  }
+
+  ChannelInfo(const ChannelInfo& aRHS)
+    : mSecurityInfo(aRHS.mSecurityInfo)
+    , mInited(aRHS.mInited)
+  {
+  }
+
+  ChannelInfo&
+  operator=(const ChannelInfo& aRHS)
+  {
+    mSecurityInfo = aRHS.mSecurityInfo;
+    mInited = aRHS.mInited;
+    return *this;
+  }
+
+  void InitFromDocument(nsIDocument* aDoc);
+  void InitFromChannel(nsIChannel* aChannel);
+  void InitFromChromeGlobal(nsIGlobalObject* aGlobal);
+  void InitFromIPCChannelInfo(const IPCChannelInfo& aChannelInfo);
+
+  // This restores every possible information stored from a previous channel
+  // object on a new one.
+  nsresult ResurrectInfoOnChannel(nsIChannel* aChannel);
+
+  bool IsInitialized() const
+  {
+    return mInited;
+  }
+
+  IPCChannelInfo AsIPCChannelInfo() const;
+
+private:
+  void SetSecurityInfo(nsISupports* aSecurityInfo);
+
+private:
+  nsCString mSecurityInfo;
+  bool mInited;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_ChannelInfo_h
diff --git a/dom/fetch/ChannelInfo.ipdlh b/dom/fetch/ChannelInfo.ipdlh
new file mode 100644
index 0000000000..605009e120
--- /dev/null
+++ b/dom/fetch/ChannelInfo.ipdlh
@@ -0,0 +1,14 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+namespace mozilla {
+namespace ipc {
+
+struct IPCChannelInfo
+{
+  nsCString securityInfo;
+};
+
+} // namespace ipc
+} // namespace mozilla
diff --git a/dom/fetch/Fetch.cpp b/dom/fetch/Fetch.cpp
new file mode 100644
index 0000000000..5c05f36024
--- /dev/null
+++ b/dom/fetch/Fetch.cpp
@@ -0,0 +1,759 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Fetch.h"
+#include "FetchConsumer.h"
+
+#include "nsIDocument.h"
+#include "nsIGlobalObject.h"
+#include "nsIStreamLoader.h"
+#include "nsIThreadRetargetableRequest.h"
+#include "nsIUnicodeDecoder.h"
+#include "nsIUnicodeEncoder.h"
+
+#include "nsCharSeparatedTokenizer.h"
+#include "nsDOMString.h"
+#include "nsNetUtil.h"
+#include "nsReadableUtils.h"
+#include "nsStreamUtils.h"
+#include "nsStringStream.h"
+#include "nsProxyRelease.h"
+
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/BodyUtil.h"
+#include "mozilla/dom/EncodingUtils.h"
+#include "mozilla/dom/Exceptions.h"
+#include "mozilla/dom/FetchDriver.h"
+#include "mozilla/dom/File.h"
+#include "mozilla/dom/FormData.h"
+#include "mozilla/dom/Headers.h"
+#include "mozilla/dom/MutableBlobStreamListener.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/PromiseWorkerProxy.h"
+#include "mozilla/dom/Request.h"
+#include "mozilla/dom/Response.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/URLSearchParams.h"
+#include "mozilla/dom/workers/ServiceWorkerManager.h"
+#include "mozilla/Telemetry.h"
+
+#include "InternalRequest.h"
+#include "InternalResponse.h"
+
+#include "WorkerPrivate.h"
+#include "WorkerRunnable.h"
+#include "WorkerScope.h"
+#include "Workers.h"
+
+namespace mozilla {
+namespace dom {
+
+using namespace workers;
+
+class WorkerFetchResolver final : public FetchDriverObserver
+{
+  friend class MainThreadFetchRunnable;
+  friend class WorkerFetchResponseEndRunnable;
+  friend class WorkerFetchResponseRunnable;
+
+  RefPtr<PromiseWorkerProxy> mPromiseProxy;
+public:
+  // Returns null if worker is shutting down.
+  static already_AddRefed<WorkerFetchResolver>
+  Create(workers::WorkerPrivate* aWorkerPrivate, Promise* aPromise)
+  {
+    MOZ_ASSERT(aWorkerPrivate);
+    aWorkerPrivate->AssertIsOnWorkerThread();
+    RefPtr<PromiseWorkerProxy> proxy = PromiseWorkerProxy::Create(aWorkerPrivate, aPromise);
+    if (!proxy) {
+      return nullptr;
+    }
+
+    RefPtr<WorkerFetchResolver> r = new WorkerFetchResolver(proxy);
+    return r.forget();
+  }
+
+  void
+  OnResponseAvailableInternal(InternalResponse* aResponse) override;
+
+  void
+  OnResponseEnd() override;
+
+private:
+  explicit WorkerFetchResolver(PromiseWorkerProxy* aProxy)
+    : mPromiseProxy(aProxy)
+  {
+    MOZ_ASSERT(!NS_IsMainThread());
+    MOZ_ASSERT(mPromiseProxy);
+  }
+
+  ~WorkerFetchResolver()
+  {}
+
+  virtual void
+  FlushConsoleReport() override;
+};
+
+class MainThreadFetchResolver final : public FetchDriverObserver
+{
+  RefPtr<Promise> mPromise;
+  RefPtr<Response> mResponse;
+
+  nsCOMPtr<nsIDocument> mDocument;
+
+  NS_DECL_OWNINGTHREAD
+public:
+  explicit MainThreadFetchResolver(Promise* aPromise);
+
+  void
+  OnResponseAvailableInternal(InternalResponse* aResponse) override;
+
+  void SetDocument(nsIDocument* aDocument)
+  {
+    mDocument = aDocument;
+  }
+
+  virtual void OnResponseEnd() override
+  {
+    FlushConsoleReport();
+  }
+
+private:
+  ~MainThreadFetchResolver();
+
+  void FlushConsoleReport() override
+  {
+    mReporter->FlushConsoleReports(mDocument);
+  }
+};
+
+class MainThreadFetchRunnable : public Runnable
+{
+  RefPtr<WorkerFetchResolver> mResolver;
+  RefPtr<InternalRequest> mRequest;
+
+public:
+  MainThreadFetchRunnable(WorkerFetchResolver* aResolver,
+                          InternalRequest* aRequest)
+    : mResolver(aResolver)
+    , mRequest(aRequest)
+  {
+    MOZ_ASSERT(mResolver);
+  }
+
+  NS_IMETHOD
+  Run() override
+  {
+    AssertIsOnMainThread();
+    RefPtr<FetchDriver> fetch;
+    RefPtr<PromiseWorkerProxy> proxy = mResolver->mPromiseProxy;
+
+    {
+      // Acquire the proxy mutex while getting data from the WorkerPrivate...
+      MutexAutoLock lock(proxy->Lock());
+      if (proxy->CleanedUp()) {
+        NS_WARNING("Aborting Fetch because worker already shut down");
+        return NS_OK;
+      }
+
+      nsCOMPtr<nsIPrincipal> principal = proxy->GetWorkerPrivate()->GetPrincipal();
+      MOZ_ASSERT(principal);
+      nsCOMPtr<nsILoadGroup> loadGroup = proxy->GetWorkerPrivate()->GetLoadGroup();
+      MOZ_ASSERT(loadGroup);
+      fetch = new FetchDriver(mRequest, principal, loadGroup);
+      nsAutoCString spec;
+      if (proxy->GetWorkerPrivate()->GetBaseURI()) {
+        proxy->GetWorkerPrivate()->GetBaseURI()->GetAsciiSpec(spec);
+      }
+      fetch->SetWorkerScript(spec);
+    }
+
+    // ...but release it before calling Fetch, because mResolver's callback can
+    // be called synchronously and they want the mutex, too.
+    return fetch->Fetch(mResolver);
+  }
+};
+
+already_AddRefed<Promise>
+FetchRequest(nsIGlobalObject* aGlobal, const RequestOrUSVString& aInput,
+             const RequestInit& aInit, ErrorResult& aRv)
+{
+  RefPtr<Promise> p = Promise::Create(aGlobal, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  // Double check that we have chrome privileges if the Request's content
+  // policy type has been overridden.  Note, we must do this before
+  // entering the global below.  Otherwise the IsCallerChrome() will
+  // always fail.
+  MOZ_ASSERT_IF(aInput.IsRequest() &&
+                aInput.GetAsRequest().IsContentPolicyTypeOverridden(),
+                nsContentUtils::IsCallerChrome());
+
+  AutoJSAPI jsapi;
+  if (!jsapi.Init(aGlobal)) {
+    aRv.Throw(NS_ERROR_NOT_AVAILABLE);
+    return nullptr;
+  }
+
+  JSContext* cx = jsapi.cx();
+  JS::Rooted<JSObject*> jsGlobal(cx, aGlobal->GetGlobalJSObject());
+  GlobalObject global(cx, jsGlobal);
+
+  RefPtr<Request> request = Request::Constructor(global, aInput, aInit, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  RefPtr<InternalRequest> r = request->GetInternalRequest();
+
+  if (NS_IsMainThread()) {
+    nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal);
+    nsCOMPtr<nsIDocument> doc;
+    nsCOMPtr<nsILoadGroup> loadGroup;
+    nsIPrincipal* principal;
+    if (window) {
+      doc = window->GetExtantDoc();
+      if (!doc) {
+        aRv.Throw(NS_ERROR_FAILURE);
+        return nullptr;
+      }
+      principal = doc->NodePrincipal();
+      loadGroup = doc->GetDocumentLoadGroup();
+    } else {
+      principal = aGlobal->PrincipalOrNull();
+      if (NS_WARN_IF(!principal)) {
+        aRv.Throw(NS_ERROR_FAILURE);
+        return nullptr;
+      }
+      nsresult rv = NS_NewLoadGroup(getter_AddRefs(loadGroup), principal);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        aRv.Throw(rv);
+        return nullptr;
+      }
+    }
+
+    Telemetry::Accumulate(Telemetry::FETCH_IS_MAINTHREAD, 1);
+
+    RefPtr<MainThreadFetchResolver> resolver = new MainThreadFetchResolver(p);
+    RefPtr<FetchDriver> fetch = new FetchDriver(r, principal, loadGroup);
+    fetch->SetDocument(doc);
+    resolver->SetDocument(doc);
+    aRv = fetch->Fetch(resolver);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+  } else {
+    WorkerPrivate* worker = GetCurrentThreadWorkerPrivate();
+    MOZ_ASSERT(worker);
+
+    Telemetry::Accumulate(Telemetry::FETCH_IS_MAINTHREAD, 0);
+
+    if (worker->IsServiceWorker()) {
+      r->SetSkipServiceWorker();
+    }
+
+    RefPtr<WorkerFetchResolver> resolver = WorkerFetchResolver::Create(worker, p);
+    if (!resolver) {
+      NS_WARNING("Could not add WorkerFetchResolver workerHolder to worker");
+      aRv.Throw(NS_ERROR_DOM_ABORT_ERR);
+      return nullptr;
+    }
+
+    RefPtr<MainThreadFetchRunnable> run = new MainThreadFetchRunnable(resolver, r);
+    worker->DispatchToMainThread(run.forget());
+  }
+
+  return p.forget();
+}
+
+MainThreadFetchResolver::MainThreadFetchResolver(Promise* aPromise)
+  : mPromise(aPromise)
+{
+}
+
+void
+MainThreadFetchResolver::OnResponseAvailableInternal(InternalResponse* aResponse)
+{
+  NS_ASSERT_OWNINGTHREAD(MainThreadFetchResolver);
+  AssertIsOnMainThread();
+
+  if (aResponse->Type() != ResponseType::Error) {
+    nsCOMPtr<nsIGlobalObject> go = mPromise->GetParentObject();
+    mResponse = new Response(go, aResponse);
+    mPromise->MaybeResolve(mResponse);
+  } else {
+    ErrorResult result;
+    result.ThrowTypeError<MSG_FETCH_FAILED>();
+    mPromise->MaybeReject(result);
+  }
+}
+
+MainThreadFetchResolver::~MainThreadFetchResolver()
+{
+  NS_ASSERT_OWNINGTHREAD(MainThreadFetchResolver);
+}
+
+class WorkerFetchResponseRunnable final : public MainThreadWorkerRunnable
+{
+  RefPtr<WorkerFetchResolver> mResolver;
+  // Passed from main thread to worker thread after being initialized.
+  RefPtr<InternalResponse> mInternalResponse;
+public:
+  WorkerFetchResponseRunnable(WorkerPrivate* aWorkerPrivate,
+                              WorkerFetchResolver* aResolver,
+                              InternalResponse* aResponse)
+    : MainThreadWorkerRunnable(aWorkerPrivate)
+    , mResolver(aResolver)
+    , mInternalResponse(aResponse)
+  {
+  }
+
+  bool
+  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
+  {
+    MOZ_ASSERT(aWorkerPrivate);
+    aWorkerPrivate->AssertIsOnWorkerThread();
+
+    RefPtr<Promise> promise = mResolver->mPromiseProxy->WorkerPromise();
+
+    if (mInternalResponse->Type() != ResponseType::Error) {
+      RefPtr<nsIGlobalObject> global = aWorkerPrivate->GlobalScope();
+      RefPtr<Response> response = new Response(global, mInternalResponse);
+      promise->MaybeResolve(response);
+    } else {
+      ErrorResult result;
+      result.ThrowTypeError<MSG_FETCH_FAILED>();
+      promise->MaybeReject(result);
+    }
+    return true;
+  }
+};
+
+class WorkerFetchResponseEndBase
+{
+  RefPtr<PromiseWorkerProxy> mPromiseProxy;
+public:
+  explicit WorkerFetchResponseEndBase(PromiseWorkerProxy* aPromiseProxy)
+    : mPromiseProxy(aPromiseProxy)
+  {
+    MOZ_ASSERT(mPromiseProxy);
+  }
+
+  void
+  WorkerRunInternal(WorkerPrivate* aWorkerPrivate)
+  {
+    MOZ_ASSERT(aWorkerPrivate);
+    aWorkerPrivate->AssertIsOnWorkerThread();
+    mPromiseProxy->CleanUp();
+  }
+};
+
+class WorkerFetchResponseEndRunnable final : public MainThreadWorkerRunnable
+                                           , public WorkerFetchResponseEndBase
+{
+public:
+  explicit WorkerFetchResponseEndRunnable(PromiseWorkerProxy* aPromiseProxy)
+    : MainThreadWorkerRunnable(aPromiseProxy->GetWorkerPrivate())
+    , WorkerFetchResponseEndBase(aPromiseProxy)
+  {
+  }
+
+  bool
+  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
+  {
+    WorkerRunInternal(aWorkerPrivate);
+    return true;
+  }
+
+  nsresult
+  Cancel() override
+  {
+    // Execute Run anyway to make sure we cleanup our promise proxy to avoid
+    // leaking the worker thread
+    Run();
+    return WorkerRunnable::Cancel();
+  }
+};
+
+class WorkerFetchResponseEndControlRunnable final : public MainThreadWorkerControlRunnable
+                                                  , public WorkerFetchResponseEndBase
+{
+public:
+  explicit WorkerFetchResponseEndControlRunnable(PromiseWorkerProxy* aPromiseProxy)
+    : MainThreadWorkerControlRunnable(aPromiseProxy->GetWorkerPrivate())
+    , WorkerFetchResponseEndBase(aPromiseProxy)
+  {
+  }
+
+  bool
+  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
+  {
+    WorkerRunInternal(aWorkerPrivate);
+    return true;
+  }
+
+  // Control runnable cancel already calls Run().
+};
+
+void
+WorkerFetchResolver::OnResponseAvailableInternal(InternalResponse* aResponse)
+{
+  AssertIsOnMainThread();
+
+  MutexAutoLock lock(mPromiseProxy->Lock());
+  if (mPromiseProxy->CleanedUp()) {
+    return;
+  }
+
+  RefPtr<WorkerFetchResponseRunnable> r =
+    new WorkerFetchResponseRunnable(mPromiseProxy->GetWorkerPrivate(), this,
+                                    aResponse);
+
+  if (!r->Dispatch()) {
+    NS_WARNING("Could not dispatch fetch response");
+  }
+}
+
+void
+WorkerFetchResolver::OnResponseEnd()
+{
+  AssertIsOnMainThread();
+  MutexAutoLock lock(mPromiseProxy->Lock());
+  if (mPromiseProxy->CleanedUp()) {
+    return;
+  }
+
+  FlushConsoleReport();
+
+  RefPtr<WorkerFetchResponseEndRunnable> r =
+    new WorkerFetchResponseEndRunnable(mPromiseProxy);
+
+  if (!r->Dispatch()) {
+    RefPtr<WorkerFetchResponseEndControlRunnable> cr =
+      new WorkerFetchResponseEndControlRunnable(mPromiseProxy);
+    // This can fail if the worker thread is canceled or killed causing
+    // the PromiseWorkerProxy to give up its WorkerHolder immediately,
+    // allowing the worker thread to become Dead.
+    if (!cr->Dispatch()) {
+      NS_WARNING("Failed to dispatch WorkerFetchResponseEndControlRunnable");
+    }
+  }
+}
+
+void
+WorkerFetchResolver::FlushConsoleReport()
+{
+  AssertIsOnMainThread();
+  MOZ_ASSERT(mPromiseProxy);
+
+  if(!mReporter) {
+    return;
+  }
+
+  workers::WorkerPrivate* worker = mPromiseProxy->GetWorkerPrivate();
+  if (!worker) {
+    mReporter->FlushConsoleReports((nsIDocument*)nullptr);
+    return;
+  }
+
+  if (worker->IsServiceWorker()) {
+    // Flush to service worker
+    RefPtr<ServiceWorkerManager> swm = ServiceWorkerManager::GetInstance();
+    if (!swm) {
+      mReporter->FlushConsoleReports((nsIDocument*)nullptr);
+      return;
+    }
+
+    swm->FlushReportsToAllClients(worker->WorkerName(), mReporter);
+    return;
+  }
+
+  if (worker->IsSharedWorker()) {
+    // Flush to shared worker
+    worker->FlushReportsToSharedWorkers(mReporter);
+    return;
+  }
+
+  // Flush to dedicated worker
+  mReporter->FlushConsoleReports(worker->GetDocument());
+}
+
+namespace {
+
+nsresult
+ExtractFromArrayBuffer(const ArrayBuffer& aBuffer,
+                       nsIInputStream** aStream,
+                       uint64_t& aContentLength)
+{
+  aBuffer.ComputeLengthAndData();
+  aContentLength = aBuffer.Length();
+  //XXXnsm reinterpret_cast<> is used in DOMParser, should be ok.
+  return NS_NewByteInputStream(aStream,
+                               reinterpret_cast<char*>(aBuffer.Data()),
+                               aBuffer.Length(), NS_ASSIGNMENT_COPY);
+}
+
+nsresult
+ExtractFromArrayBufferView(const ArrayBufferView& aBuffer,
+                           nsIInputStream** aStream,
+                           uint64_t& aContentLength)
+{
+  aBuffer.ComputeLengthAndData();
+  aContentLength = aBuffer.Length();
+  //XXXnsm reinterpret_cast<> is used in DOMParser, should be ok.
+  return NS_NewByteInputStream(aStream,
+                               reinterpret_cast<char*>(aBuffer.Data()),
+                               aBuffer.Length(), NS_ASSIGNMENT_COPY);
+}
+
+nsresult
+ExtractFromBlob(const Blob& aBlob,
+                nsIInputStream** aStream,
+                nsCString& aContentType,
+                uint64_t& aContentLength)
+{
+  RefPtr<BlobImpl> impl = aBlob.Impl();
+  ErrorResult rv;
+  aContentLength = impl->GetSize(rv);
+  if (NS_WARN_IF(rv.Failed())) {
+    return rv.StealNSResult();
+  }
+
+  impl->GetInternalStream(aStream, rv);
+  if (NS_WARN_IF(rv.Failed())) {
+    return rv.StealNSResult();
+  }
+
+  nsAutoString type;
+  impl->GetType(type);
+  aContentType = NS_ConvertUTF16toUTF8(type);
+  return NS_OK;
+}
+
+nsresult
+ExtractFromFormData(FormData& aFormData,
+                    nsIInputStream** aStream,
+                    nsCString& aContentType,
+                    uint64_t& aContentLength)
+{
+  nsAutoCString unusedCharset;
+  return aFormData.GetSendInfo(aStream, &aContentLength,
+                               aContentType, unusedCharset);
+}
+
+nsresult
+ExtractFromUSVString(const nsString& aStr,
+                     nsIInputStream** aStream,
+                     nsCString& aContentType,
+                     uint64_t& aContentLength)
+{
+  nsCOMPtr<nsIUnicodeEncoder> encoder = EncodingUtils::EncoderForEncoding("UTF-8");
+  if (!encoder) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  int32_t destBufferLen;
+  nsresult rv = encoder->GetMaxLength(aStr.get(), aStr.Length(), &destBufferLen);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  nsCString encoded;
+  if (!encoded.SetCapacity(destBufferLen, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  char* destBuffer = encoded.BeginWriting();
+  int32_t srcLen = (int32_t) aStr.Length();
+  int32_t outLen = destBufferLen;
+  rv = encoder->Convert(aStr.get(), &srcLen, destBuffer, &outLen);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  MOZ_ASSERT(outLen <= destBufferLen);
+  encoded.SetLength(outLen);
+
+  aContentType = NS_LITERAL_CSTRING("text/plain;charset=UTF-8");
+  aContentLength = outLen;
+
+  return NS_NewCStringInputStream(aStream, encoded);
+}
+
+nsresult
+ExtractFromURLSearchParams(const URLSearchParams& aParams,
+                           nsIInputStream** aStream,
+                           nsCString& aContentType,
+                           uint64_t& aContentLength)
+{
+  nsAutoString serialized;
+  aParams.Stringify(serialized);
+  aContentType = NS_LITERAL_CSTRING("application/x-www-form-urlencoded;charset=UTF-8");
+  aContentLength = serialized.Length();
+  return NS_NewCStringInputStream(aStream, NS_ConvertUTF16toUTF8(serialized));
+}
+} // namespace
+
+nsresult
+ExtractByteStreamFromBody(const OwningArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams& aBodyInit,
+                          nsIInputStream** aStream,
+                          nsCString& aContentType,
+                          uint64_t& aContentLength)
+{
+  MOZ_ASSERT(aStream);
+
+  if (aBodyInit.IsArrayBuffer()) {
+    const ArrayBuffer& buf = aBodyInit.GetAsArrayBuffer();
+    return ExtractFromArrayBuffer(buf, aStream, aContentLength);
+  }
+  if (aBodyInit.IsArrayBufferView()) {
+    const ArrayBufferView& buf = aBodyInit.GetAsArrayBufferView();
+    return ExtractFromArrayBufferView(buf, aStream, aContentLength);
+  }
+  if (aBodyInit.IsBlob()) {
+    const Blob& blob = aBodyInit.GetAsBlob();
+    return ExtractFromBlob(blob, aStream, aContentType, aContentLength);
+  }
+  if (aBodyInit.IsFormData()) {
+    FormData& form = aBodyInit.GetAsFormData();
+    return ExtractFromFormData(form, aStream, aContentType, aContentLength);
+  }
+  if (aBodyInit.IsUSVString()) {
+    nsAutoString str;
+    str.Assign(aBodyInit.GetAsUSVString());
+    return ExtractFromUSVString(str, aStream, aContentType, aContentLength);
+  }
+  if (aBodyInit.IsURLSearchParams()) {
+    URLSearchParams& params = aBodyInit.GetAsURLSearchParams();
+    return ExtractFromURLSearchParams(params, aStream, aContentType, aContentLength);
+  }
+
+  NS_NOTREACHED("Should never reach here");
+  return NS_ERROR_FAILURE;
+}
+
+nsresult
+ExtractByteStreamFromBody(const ArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams& aBodyInit,
+                          nsIInputStream** aStream,
+                          nsCString& aContentType,
+                          uint64_t& aContentLength)
+{
+  MOZ_ASSERT(aStream);
+  MOZ_ASSERT(!*aStream);
+
+  if (aBodyInit.IsArrayBuffer()) {
+    const ArrayBuffer& buf = aBodyInit.GetAsArrayBuffer();
+    return ExtractFromArrayBuffer(buf, aStream, aContentLength);
+  }
+  if (aBodyInit.IsArrayBufferView()) {
+    const ArrayBufferView& buf = aBodyInit.GetAsArrayBufferView();
+    return ExtractFromArrayBufferView(buf, aStream, aContentLength);
+  }
+  if (aBodyInit.IsBlob()) {
+    const Blob& blob = aBodyInit.GetAsBlob();
+    return ExtractFromBlob(blob, aStream, aContentType, aContentLength);
+  }
+  if (aBodyInit.IsFormData()) {
+    FormData& form = aBodyInit.GetAsFormData();
+    return ExtractFromFormData(form, aStream, aContentType, aContentLength);
+  }
+  if (aBodyInit.IsUSVString()) {
+    nsAutoString str;
+    str.Assign(aBodyInit.GetAsUSVString());
+    return ExtractFromUSVString(str, aStream, aContentType, aContentLength);
+  }
+  if (aBodyInit.IsURLSearchParams()) {
+    URLSearchParams& params = aBodyInit.GetAsURLSearchParams();
+    return ExtractFromURLSearchParams(params, aStream, aContentType, aContentLength);
+  }
+
+  NS_NOTREACHED("Should never reach here");
+  return NS_ERROR_FAILURE;
+}
+
+template <class Derived>
+FetchBody<Derived>::FetchBody()
+  : mWorkerPrivate(nullptr)
+  , mBodyUsed(false)
+{
+  if (!NS_IsMainThread()) {
+    mWorkerPrivate = GetCurrentThreadWorkerPrivate();
+    MOZ_ASSERT(mWorkerPrivate);
+  }
+}
+
+template
+FetchBody<Request>::FetchBody();
+
+template
+FetchBody<Response>::FetchBody();
+
+template <class Derived>
+FetchBody<Derived>::~FetchBody()
+{
+}
+
+template <class Derived>
+already_AddRefed<Promise>
+FetchBody<Derived>::ConsumeBody(FetchConsumeType aType, ErrorResult& aRv)
+{
+  if (BodyUsed()) {
+    aRv.ThrowTypeError<MSG_FETCH_BODY_CONSUMED_ERROR>();
+    return nullptr;
+  }
+
+  SetBodyUsed();
+
+  RefPtr<Promise> promise =
+    FetchBodyConsumer<Derived>::Create(DerivedClass()->GetParentObject(),
+                                       this, aType, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  return promise.forget();
+}
+
+template
+already_AddRefed<Promise>
+FetchBody<Request>::ConsumeBody(FetchConsumeType aType, ErrorResult& aRv);
+
+template
+already_AddRefed<Promise>
+FetchBody<Response>::ConsumeBody(FetchConsumeType aType, ErrorResult& aRv);
+
+template <class Derived>
+void
+FetchBody<Derived>::SetMimeType()
+{
+  // Extract mime type.
+  ErrorResult result;
+  nsCString contentTypeValues;
+  MOZ_ASSERT(DerivedClass()->GetInternalHeaders());
+  DerivedClass()->GetInternalHeaders()->Get(NS_LITERAL_CSTRING("Content-Type"),
+                                            contentTypeValues, result);
+  MOZ_ALWAYS_TRUE(!result.Failed());
+
+  // HTTP ABNF states Content-Type may have only one value.
+  // This is from the "parse a header value" of the fetch spec.
+  if (!contentTypeValues.IsVoid() && contentTypeValues.Find(",") == -1) {
+    mMimeType = contentTypeValues;
+    ToLowerCase(mMimeType);
+  }
+}
+
+template
+void
+FetchBody<Request>::SetMimeType();
+
+template
+void
+FetchBody<Response>::SetMimeType();
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/Fetch.h b/dom/fetch/Fetch.h
new file mode 100644
index 0000000000..fc50d3fda0
--- /dev/null
+++ b/dom/fetch/Fetch.h
@@ -0,0 +1,205 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_Fetch_h
+#define mozilla_dom_Fetch_h
+
+#include "nsAutoPtr.h"
+#include "nsIStreamLoader.h"
+
+#include "nsCOMPtr.h"
+#include "nsError.h"
+#include "nsProxyRelease.h"
+#include "nsString.h"
+
+#include "mozilla/DebugOnly.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/RequestBinding.h"
+
+class nsIGlobalObject;
+
+namespace mozilla {
+namespace dom {
+
+class ArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams;
+class BlobImpl;
+class InternalRequest;
+class OwningArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams;
+class RequestOrUSVString;
+
+namespace workers {
+class WorkerPrivate;
+} // namespace workers
+
+already_AddRefed<Promise>
+FetchRequest(nsIGlobalObject* aGlobal, const RequestOrUSVString& aInput,
+             const RequestInit& aInit, ErrorResult& aRv);
+
+nsresult
+UpdateRequestReferrer(nsIGlobalObject* aGlobal, InternalRequest* aRequest);
+
+/*
+ * Creates an nsIInputStream based on the fetch specifications 'extract a byte
+ * stream algorithm' - http://fetch.spec.whatwg.org/#concept-bodyinit-extract.
+ * Stores content type in out param aContentType.
+ */
+nsresult
+ExtractByteStreamFromBody(const OwningArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams& aBodyInit,
+                          nsIInputStream** aStream,
+                          nsCString& aContentType,
+                          uint64_t& aContentLength);
+
+/*
+ * Non-owning version.
+ */
+nsresult
+ExtractByteStreamFromBody(const ArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams& aBodyInit,
+                          nsIInputStream** aStream,
+                          nsCString& aContentType,
+                          uint64_t& aContentLength);
+
+template <class Derived> class FetchBodyConsumer;
+
+enum FetchConsumeType
+{
+  CONSUME_ARRAYBUFFER,
+  CONSUME_BLOB,
+  CONSUME_FORMDATA,
+  CONSUME_JSON,
+  CONSUME_TEXT,
+};
+
+/*
+ * FetchBody's body consumption uses nsIInputStreamPump to read from the
+ * underlying stream to a block of memory, which is then adopted by
+ * ContinueConsumeBody() and converted to the right type based on the JS
+ * function called.
+ *
+ * Use of the nsIInputStreamPump complicates things on the worker thread.
+ * The solution used here is similar to WebSockets.
+ * The difference is that we are only interested in completion and not data
+ * events, and nsIInputStreamPump can only deliver completion on the main thread.
+ *
+ * Before starting the pump on the main thread, we addref the FetchBody to keep
+ * it alive. Then we add a feature, to track the status of the worker.
+ *
+ * ContinueConsumeBody() is the function that cleans things up in both success
+ * and error conditions and so all callers call it with the appropriate status.
+ *
+ * Once the read is initiated on the main thread there are two possibilities.
+ *
+ * 1) Pump finishes before worker has finished Running.
+ *    In this case we adopt the data and dispatch a runnable to the worker,
+ *    which derefs FetchBody and removes the feature and resolves the Promise.
+ *
+ * 2) Pump still working while worker has stopped Running.
+ *    The feature is Notify()ed and ContinueConsumeBody() is called with
+ *    NS_BINDING_ABORTED. We first Cancel() the pump using a sync runnable to
+ *    ensure that mFetchBody remains alive (since mConsumeBodyPump is strongly
+ *    held by it) until pump->Cancel() is called. OnStreamComplete() will not
+ *    do anything if the error code is NS_BINDING_ABORTED, so we don't have to
+ *    worry about keeping anything alive.
+ *
+ * The pump is always released on the main thread.
+ */
+template <class Derived>
+class FetchBody
+{
+public:
+  friend class FetchBodyConsumer<Derived>;
+
+  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) = 0;
+  NS_IMETHOD_(MozExternalRefCountType) Release(void) = 0;
+
+  bool
+  BodyUsed() const { return mBodyUsed; }
+
+  already_AddRefed<Promise>
+  ArrayBuffer(ErrorResult& aRv)
+  {
+    return ConsumeBody(CONSUME_ARRAYBUFFER, aRv);
+  }
+
+  already_AddRefed<Promise>
+  Blob(ErrorResult& aRv)
+  {
+    return ConsumeBody(CONSUME_BLOB, aRv);
+  }
+
+  already_AddRefed<Promise>
+  FormData(ErrorResult& aRv)
+  {
+    return ConsumeBody(CONSUME_FORMDATA, aRv);
+  }
+
+  already_AddRefed<Promise>
+  Json(ErrorResult& aRv)
+  {
+    return ConsumeBody(CONSUME_JSON, aRv);
+  }
+
+  already_AddRefed<Promise>
+  Text(ErrorResult& aRv)
+  {
+    return ConsumeBody(CONSUME_TEXT, aRv);
+  }
+
+  // Utility public methods accessed by various runnables.
+
+  void
+  SetBodyUsed()
+  {
+    mBodyUsed = true;
+  }
+
+  const nsCString&
+  MimeType() const
+  {
+    return mMimeType;
+  }
+
+protected:
+  FetchBody();
+
+  // Always set whenever the FetchBody is created on the worker thread.
+  workers::WorkerPrivate* mWorkerPrivate;
+
+  virtual ~FetchBody();
+
+  void
+  SetMimeType();
+private:
+  Derived*
+  DerivedClass() const
+  {
+    return static_cast<Derived*>(const_cast<FetchBody*>(this));
+  }
+
+  already_AddRefed<Promise>
+  ConsumeBody(FetchConsumeType aType, ErrorResult& aRv);
+
+  bool
+  IsOnTargetThread()
+  {
+    return NS_IsMainThread() == !mWorkerPrivate;
+  }
+
+  void
+  AssertIsOnTargetThread()
+  {
+    MOZ_ASSERT(IsOnTargetThread());
+  }
+
+  // Only ever set once, always on target thread.
+  bool mBodyUsed;
+  nsCString mMimeType;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_Fetch_h
diff --git a/dom/fetch/FetchConsumer.cpp b/dom/fetch/FetchConsumer.cpp
new file mode 100644
index 0000000000..42dfcbaba9
--- /dev/null
+++ b/dom/fetch/FetchConsumer.cpp
@@ -0,0 +1,705 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Fetch.h"
+#include "FetchConsumer.h"
+
+#include "nsIInputStreamPump.h"
+#include "nsProxyRelease.h"
+#include "WorkerPrivate.h"
+#include "WorkerRunnable.h"
+#include "WorkerScope.h"
+#include "Workers.h"
+
+namespace mozilla {
+namespace dom {
+
+using namespace workers;
+
+namespace {
+
+template <class Derived>
+class FetchBodyWorkerHolder final : public workers::WorkerHolder
+{
+  RefPtr<FetchBodyConsumer<Derived>> mConsumer;
+  bool mWasNotified;
+
+public:
+  explicit FetchBodyWorkerHolder(FetchBodyConsumer<Derived>* aConsumer)
+    : mConsumer(aConsumer)
+    , mWasNotified(false)
+  {
+    MOZ_ASSERT(aConsumer);
+  }
+
+  ~FetchBodyWorkerHolder() = default;
+
+  bool Notify(workers::Status aStatus) override
+  {
+    MOZ_ASSERT(aStatus > workers::Running);
+    if (!mWasNotified) {
+      mWasNotified = true;
+      mConsumer->ShutDownMainThreadConsuming();
+    }
+
+    return true;
+  }
+};
+
+template <class Derived>
+class BeginConsumeBodyRunnable final : public Runnable
+{
+  RefPtr<FetchBodyConsumer<Derived>> mFetchBodyConsumer;
+
+public:
+  explicit BeginConsumeBodyRunnable(FetchBodyConsumer<Derived>* aConsumer)
+    : mFetchBodyConsumer(aConsumer)
+  { }
+
+  NS_IMETHOD
+  Run() override
+  {
+    mFetchBodyConsumer->BeginConsumeBodyMainThread();
+    return NS_OK;
+  }
+};
+
+/*
+ * Called on successfully reading the complete stream.
+ */
+template <class Derived>
+class ContinueConsumeBodyRunnable final : public MainThreadWorkerRunnable
+{
+  RefPtr<FetchBodyConsumer<Derived>> mFetchBodyConsumer;
+  nsresult mStatus;
+  uint32_t mLength;
+  uint8_t* mResult;
+
+public:
+  ContinueConsumeBodyRunnable(FetchBodyConsumer<Derived>* aFetchBodyConsumer,
+                              nsresult aStatus, uint32_t aLength,
+                              uint8_t* aResult)
+    : MainThreadWorkerRunnable(aFetchBodyConsumer->GetWorkerPrivate())
+    , mFetchBodyConsumer(aFetchBodyConsumer)
+    , mStatus(aStatus)
+    , mLength(aLength)
+    , mResult(aResult)
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
+
+  bool
+  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
+  {
+    mFetchBodyConsumer->ContinueConsumeBody(mStatus, mLength, mResult);
+    return true;
+  }
+};
+
+template <class Derived>
+class FailConsumeBodyWorkerRunnable : public MainThreadWorkerControlRunnable
+{
+  RefPtr<FetchBodyConsumer<Derived>> mBodyConsumer;
+
+public:
+  explicit FailConsumeBodyWorkerRunnable(FetchBodyConsumer<Derived>* aBodyConsumer)
+    : MainThreadWorkerControlRunnable(aBodyConsumer->GetWorkerPrivate())
+    , mBodyConsumer(aBodyConsumer)
+  {
+    AssertIsOnMainThread();
+  }
+
+  bool
+  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
+  {
+    mBodyConsumer->ContinueConsumeBody(NS_ERROR_FAILURE, 0, nullptr);
+    return true;
+  }
+};
+
+/*
+ * In case of failure to create a stream pump or dispatch stream completion to
+ * worker, ensure we cleanup properly. Thread agnostic.
+ */
+template <class Derived>
+class MOZ_STACK_CLASS AutoFailConsumeBody final
+{
+  RefPtr<FetchBodyConsumer<Derived>> mBodyConsumer;
+
+public:
+  explicit AutoFailConsumeBody(FetchBodyConsumer<Derived>* aBodyConsumer)
+    : mBodyConsumer(aBodyConsumer)
+  {}
+
+  ~AutoFailConsumeBody()
+  {
+    AssertIsOnMainThread();
+
+    if (mBodyConsumer) {
+      if (mBodyConsumer->GetWorkerPrivate()) {
+        RefPtr<FailConsumeBodyWorkerRunnable<Derived>> r =
+          new FailConsumeBodyWorkerRunnable<Derived>(mBodyConsumer);
+        if (!r->Dispatch()) {
+          MOZ_CRASH("We are going to leak");
+        }
+      } else {
+        mBodyConsumer->ContinueConsumeBody(NS_ERROR_FAILURE, 0, nullptr);
+      }
+    }
+  }
+
+  void
+  DontFail()
+  {
+    mBodyConsumer = nullptr;
+  }
+};
+
+/*
+ * Called on successfully reading the complete stream for Blob.
+ */
+template <class Derived>
+class ContinueConsumeBlobBodyRunnable final : public MainThreadWorkerRunnable
+{
+  RefPtr<FetchBodyConsumer<Derived>> mFetchBodyConsumer;
+  RefPtr<BlobImpl> mBlobImpl;
+
+public:
+  ContinueConsumeBlobBodyRunnable(FetchBodyConsumer<Derived>* aFetchBodyConsumer,
+                                  BlobImpl* aBlobImpl)
+    : MainThreadWorkerRunnable(aFetchBodyConsumer->GetWorkerPrivate())
+    , mFetchBodyConsumer(aFetchBodyConsumer)
+    , mBlobImpl(aBlobImpl)
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+    MOZ_ASSERT(mBlobImpl);
+  }
+
+  bool
+  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
+  {
+    mFetchBodyConsumer->ContinueConsumeBlobBody(mBlobImpl);
+    return true;
+  }
+};
+
+template <class Derived>
+class ConsumeBodyDoneObserver : public nsIStreamLoaderObserver
+                              , public MutableBlobStorageCallback
+{
+  RefPtr<FetchBodyConsumer<Derived>> mFetchBodyConsumer;
+
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  explicit ConsumeBodyDoneObserver(FetchBodyConsumer<Derived>* aFetchBodyConsumer)
+    : mFetchBodyConsumer(aFetchBodyConsumer)
+  { }
+
+  NS_IMETHOD
+  OnStreamComplete(nsIStreamLoader* aLoader,
+                   nsISupports* aCtxt,
+                   nsresult aStatus,
+                   uint32_t aResultLength,
+                   const uint8_t* aResult) override
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    // The loading is completed. Let's nullify the pump before continuing the
+    // consuming of the body.
+    mFetchBodyConsumer->NullifyConsumeBodyPump();
+
+    uint8_t* nonconstResult = const_cast<uint8_t*>(aResult);
+    if (mFetchBodyConsumer->GetWorkerPrivate()) {
+      RefPtr<ContinueConsumeBodyRunnable<Derived>> r =
+        new ContinueConsumeBodyRunnable<Derived>(mFetchBodyConsumer,
+                                                 aStatus,
+                                                 aResultLength,
+                                                 nonconstResult);
+      if (!r->Dispatch()) {
+        NS_WARNING("Could not dispatch ConsumeBodyRunnable");
+        // Return failure so that aResult is freed.
+        return NS_ERROR_FAILURE;
+      }
+    } else {
+      mFetchBodyConsumer->ContinueConsumeBody(aStatus, aResultLength,
+                                              nonconstResult);
+    }
+
+    // FetchBody is responsible for data.
+    return NS_SUCCESS_ADOPTED_DATA;
+  }
+
+  virtual void BlobStoreCompleted(MutableBlobStorage* aBlobStorage,
+                                  Blob* aBlob,
+                                  nsresult aRv) override
+  {
+    // On error.
+    if (NS_FAILED(aRv)) {
+      OnStreamComplete(nullptr, nullptr, aRv, 0, nullptr);
+      return;
+    }
+
+    // The loading is completed. Let's nullify the pump before continuing the
+    // consuming of the body.
+    mFetchBodyConsumer->NullifyConsumeBodyPump();
+
+    MOZ_ASSERT(aBlob);
+
+    if (mFetchBodyConsumer->GetWorkerPrivate()) {
+      RefPtr<ContinueConsumeBlobBodyRunnable<Derived>> r =
+        new ContinueConsumeBlobBodyRunnable<Derived>(mFetchBodyConsumer,
+                                                     aBlob->Impl());
+
+      if (!r->Dispatch()) {
+        NS_WARNING("Could not dispatch ConsumeBlobBodyRunnable");
+        return;
+      }
+    } else {
+      mFetchBodyConsumer->ContinueConsumeBlobBody(aBlob->Impl());
+    }
+  }
+
+private:
+  virtual ~ConsumeBodyDoneObserver()
+  { }
+};
+
+template <class Derived>
+NS_IMPL_ADDREF(ConsumeBodyDoneObserver<Derived>)
+template <class Derived>
+NS_IMPL_RELEASE(ConsumeBodyDoneObserver<Derived>)
+template <class Derived>
+NS_INTERFACE_MAP_BEGIN(ConsumeBodyDoneObserver<Derived>)
+  NS_INTERFACE_MAP_ENTRY(nsIStreamLoaderObserver)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIStreamLoaderObserver)
+NS_INTERFACE_MAP_END
+
+} // anonymous
+
+template <class Derived>
+/* static */ already_AddRefed<Promise>
+FetchBodyConsumer<Derived>::Create(nsIGlobalObject* aGlobal,
+                                   FetchBody<Derived>* aBody,
+                                   FetchConsumeType aType,
+                                   ErrorResult& aRv)
+{
+  MOZ_ASSERT(aBody);
+
+  nsCOMPtr<nsIInputStream> bodyStream;
+  aBody->DerivedClass()->GetBody(getter_AddRefs(bodyStream));
+  if (!bodyStream) {
+    aRv = NS_NewCStringInputStream(getter_AddRefs(bodyStream), EmptyCString());
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+  }
+
+  RefPtr<Promise> promise = Promise::Create(aGlobal, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  WorkerPrivate* workerPrivate = nullptr;
+  if (!NS_IsMainThread()) {
+    workerPrivate = GetCurrentThreadWorkerPrivate();
+    MOZ_ASSERT(workerPrivate);
+  }
+
+  RefPtr<FetchBodyConsumer<Derived>> consumer =
+    new FetchBodyConsumer<Derived>(aGlobal, workerPrivate, aBody, bodyStream,
+                                   promise, aType);
+
+  if (!NS_IsMainThread()) {
+    MOZ_ASSERT(workerPrivate);
+    if (NS_WARN_IF(!consumer->RegisterWorkerHolder())) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return nullptr;
+    }
+  } else {
+    nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
+    if (NS_WARN_IF(!os)) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return nullptr;
+    }
+
+    aRv = os->AddObserver(consumer, DOM_WINDOW_DESTROYED_TOPIC, true);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+
+    aRv = os->AddObserver(consumer, DOM_WINDOW_FROZEN_TOPIC, true);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+  }
+
+  nsCOMPtr<nsIRunnable> r = new BeginConsumeBodyRunnable<Derived>(consumer);
+
+  if (workerPrivate) {
+    aRv = workerPrivate->DispatchToMainThread(r.forget());
+  } else {
+    aRv = NS_DispatchToMainThread(r.forget());
+  }
+
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  return promise.forget();
+}
+
+template <class Derived>
+void
+FetchBodyConsumer<Derived>::ReleaseObject()
+{
+  AssertIsOnTargetThread();
+
+  if (NS_IsMainThread()) {
+    nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
+    if (os) {
+      os->RemoveObserver(this, DOM_WINDOW_DESTROYED_TOPIC);
+      os->RemoveObserver(this, DOM_WINDOW_FROZEN_TOPIC);
+    }
+  }
+
+  mGlobal = nullptr;
+  mWorkerHolder = nullptr;
+
+#ifdef DEBUG
+  mBody = nullptr;
+#endif
+}
+
+template <class Derived>
+FetchBodyConsumer<Derived>::FetchBodyConsumer(nsIGlobalObject* aGlobalObject,
+                                              WorkerPrivate* aWorkerPrivate,
+                                              FetchBody<Derived>* aBody,
+                                              nsIInputStream* aBodyStream,
+                                              Promise* aPromise,
+                                              FetchConsumeType aType)
+  : mTargetThread(NS_GetCurrentThread())
+#ifdef DEBUG
+  , mBody(aBody)
+#endif
+  , mBodyStream(aBodyStream)
+  , mBlobStorageType(MutableBlobStorage::eOnlyInMemory)
+  , mGlobal(aGlobalObject)
+  , mWorkerPrivate(aWorkerPrivate)
+  , mConsumeType(aType)
+  , mConsumePromise(aPromise)
+  , mBodyConsumed(false)
+  , mShuttingDown(false)
+{
+  MOZ_ASSERT(aBody);
+  MOZ_ASSERT(aBodyStream);
+  MOZ_ASSERT(aPromise);
+
+  const mozilla::UniquePtr<mozilla::ipc::PrincipalInfo>& principalInfo =
+    aBody->DerivedClass()->GetPrincipalInfo();
+  // We support temporary file for blobs only if the principal is known and
+  // it's system or content not in private Browsing.
+  if (principalInfo &&
+      (principalInfo->type() == mozilla::ipc::PrincipalInfo::TSystemPrincipalInfo ||
+       (principalInfo->type() == mozilla::ipc::PrincipalInfo::TContentPrincipalInfo &&
+        principalInfo->get_ContentPrincipalInfo().attrs().mPrivateBrowsingId == 0))) {
+    mBlobStorageType = MutableBlobStorage::eCouldBeInTemporaryFile;
+  }
+
+  mBodyMimeType = aBody->MimeType();
+}
+
+template <class Derived>
+FetchBodyConsumer<Derived>::~FetchBodyConsumer()
+{
+}
+
+template <class Derived>
+void
+FetchBodyConsumer<Derived>::AssertIsOnTargetThread() const
+{
+  MOZ_ASSERT(NS_GetCurrentThread() == mTargetThread);
+}
+
+template <class Derived>
+bool
+FetchBodyConsumer<Derived>::RegisterWorkerHolder()
+{
+  MOZ_ASSERT(mWorkerPrivate);
+  mWorkerPrivate->AssertIsOnWorkerThread();
+
+  MOZ_ASSERT(!mWorkerHolder);
+  mWorkerHolder.reset(new FetchBodyWorkerHolder<Derived>(this));
+
+  if (!mWorkerHolder->HoldWorker(mWorkerPrivate, Closing)) {
+    NS_WARNING("Failed to add workerHolder");
+    mWorkerHolder = nullptr;
+    return false;
+  }
+
+  return true;
+}
+
+/*
+ * BeginConsumeBodyMainThread() will automatically reject the consume promise
+ * and clean up on any failures, so there is no need for callers to do so,
+ * reflected in a lack of error return code.
+ */
+template <class Derived>
+void
+FetchBodyConsumer<Derived>::BeginConsumeBodyMainThread()
+{
+  AssertIsOnMainThread();
+
+  AutoFailConsumeBody<Derived> autoReject(this);
+
+  if (mShuttingDown) {
+    // We haven't started yet, but we have been terminated. AutoFailConsumeBody
+    // will dispatch a runnable to release resources.
+    return;
+  }
+
+  nsCOMPtr<nsIInputStreamPump> pump;
+  nsresult rv = NS_NewInputStreamPump(getter_AddRefs(pump),
+                                      mBodyStream, -1, -1, 0, 0, false);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return;
+  }
+
+  RefPtr<ConsumeBodyDoneObserver<Derived>> p =
+   new ConsumeBodyDoneObserver<Derived>(this);
+
+  nsCOMPtr<nsIStreamListener> listener;
+  if (mConsumeType == CONSUME_BLOB) {
+    listener = new MutableBlobStreamListener(mBlobStorageType, nullptr,
+                                             mBodyMimeType, p);
+  } else {
+    nsCOMPtr<nsIStreamLoader> loader;
+    rv = NS_NewStreamLoader(getter_AddRefs(loader), p);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return;
+    }
+
+    listener = loader;
+  }
+
+  rv = pump->AsyncRead(listener, nullptr);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return;
+  }
+
+  // Now that everything succeeded, we can assign the pump to a pointer that
+  // stays alive for the lifetime of the FetchConsumer.
+  mConsumeBodyPump = pump;
+
+  // It is ok for retargeting to fail and reads to happen on the main thread.
+  autoReject.DontFail();
+
+  // Try to retarget, otherwise fall back to main thread.
+  nsCOMPtr<nsIThreadRetargetableRequest> rr = do_QueryInterface(pump);
+  if (rr) {
+    nsCOMPtr<nsIEventTarget> sts = do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID);
+    rv = rr->RetargetDeliveryTo(sts);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      NS_WARNING("Retargeting failed");
+    }
+  }
+}
+
+template <class Derived>
+void
+FetchBodyConsumer<Derived>::ContinueConsumeBody(nsresult aStatus,
+                                                uint32_t aResultLength,
+                                                uint8_t* aResult)
+{
+  AssertIsOnTargetThread();
+
+  if (mBodyConsumed) {
+    return;
+  }
+  mBodyConsumed = true;
+
+  // Just a precaution to ensure ContinueConsumeBody is not called out of
+  // sync with a body read.
+  MOZ_ASSERT(mBody->BodyUsed());
+
+  auto autoFree = mozilla::MakeScopeExit([&] {
+    free(aResult);
+  });
+
+  MOZ_ASSERT(mConsumePromise);
+  RefPtr<Promise> localPromise = mConsumePromise.forget();
+
+  RefPtr<FetchBodyConsumer<Derived>> self = this;
+  auto autoReleaseObject = mozilla::MakeScopeExit([&] {
+    self->ReleaseObject();
+  });
+
+  if (NS_WARN_IF(NS_FAILED(aStatus))) {
+    localPromise->MaybeReject(NS_ERROR_DOM_ABORT_ERR);
+  }
+
+  // Don't warn here since we warned above.
+  if (NS_FAILED(aStatus)) {
+    return;
+  }
+
+  // Finish successfully consuming body according to type.
+  MOZ_ASSERT(aResult);
+
+  AutoJSAPI jsapi;
+  if (!jsapi.Init(mGlobal)) {
+    localPromise->MaybeReject(NS_ERROR_UNEXPECTED);
+    return;
+  }
+
+  JSContext* cx = jsapi.cx();
+  ErrorResult error;
+
+  switch (mConsumeType) {
+    case CONSUME_ARRAYBUFFER: {
+      JS::Rooted<JSObject*> arrayBuffer(cx);
+      BodyUtil::ConsumeArrayBuffer(cx, &arrayBuffer, aResultLength, aResult,
+                                   error);
+
+      if (!error.Failed()) {
+        JS::Rooted<JS::Value> val(cx);
+        val.setObjectOrNull(arrayBuffer);
+
+        localPromise->MaybeResolve(cx, val);
+        // ArrayBuffer takes over ownership.
+        aResult = nullptr;
+      }
+      break;
+    }
+    case CONSUME_BLOB: {
+      MOZ_CRASH("This should not happen.");
+      break;
+    }
+    case CONSUME_FORMDATA: {
+      nsCString data;
+      data.Adopt(reinterpret_cast<char*>(aResult), aResultLength);
+      aResult = nullptr;
+
+      RefPtr<dom::FormData> fd =
+        BodyUtil::ConsumeFormData(mGlobal, mBodyMimeType, data, error);
+      if (!error.Failed()) {
+        localPromise->MaybeResolve(fd);
+      }
+      break;
+    }
+    case CONSUME_TEXT:
+      // fall through handles early exit.
+    case CONSUME_JSON: {
+      nsString decoded;
+      if (NS_SUCCEEDED(BodyUtil::ConsumeText(aResultLength, aResult, decoded))) {
+        if (mConsumeType == CONSUME_TEXT) {
+          localPromise->MaybeResolve(decoded);
+        } else {
+          JS::Rooted<JS::Value> json(cx);
+          BodyUtil::ConsumeJson(cx, &json, decoded, error);
+          if (!error.Failed()) {
+            localPromise->MaybeResolve(cx, json);
+          }
+        }
+      };
+      break;
+    }
+    default:
+      NS_NOTREACHED("Unexpected consume body type");
+  }
+
+  error.WouldReportJSException();
+  if (error.Failed()) {
+    localPromise->MaybeReject(error);
+  }
+}
+
+template <class Derived>
+void
+FetchBodyConsumer<Derived>::ContinueConsumeBlobBody(BlobImpl* aBlobImpl)
+{
+  AssertIsOnTargetThread();
+  MOZ_ASSERT(mConsumeType == CONSUME_BLOB);
+
+  if (mBodyConsumed) {
+    return;
+  }
+  mBodyConsumed = true;
+
+  // Just a precaution to ensure ContinueConsumeBody is not called out of
+  // sync with a body read.
+  MOZ_ASSERT(mBody->BodyUsed());
+
+  MOZ_ASSERT(mConsumePromise);
+  RefPtr<Promise> localPromise = mConsumePromise.forget();
+
+  RefPtr<dom::Blob> blob = dom::Blob::Create(mGlobal, aBlobImpl);
+  MOZ_ASSERT(blob);
+
+  localPromise->MaybeResolve(blob);
+
+  ReleaseObject();
+}
+
+template <class Derived>
+void
+FetchBodyConsumer<Derived>::ShutDownMainThreadConsuming()
+{
+  if (!NS_IsMainThread()) {
+    RefPtr<FetchBodyConsumer<Derived>> self = this;
+
+    nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction(
+      [self] () { self->ShutDownMainThreadConsuming(); });
+
+    WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
+    MOZ_ASSERT(workerPrivate);
+    workerPrivate->DispatchToMainThread(r.forget());
+    return;
+  }
+
+  // We need this because maybe, mConsumeBodyPump has not been created yet. We
+  // must be sure that we don't try to do it.
+  mShuttingDown = true;
+
+  if (mConsumeBodyPump) {
+    mConsumeBodyPump->Cancel(NS_BINDING_ABORTED);
+    mConsumeBodyPump = nullptr;
+  }
+}
+
+template <class Derived>
+NS_IMETHODIMP
+FetchBodyConsumer<Derived>::Observe(nsISupports* aSubject,
+                                    const char* aTopic,
+                                    const char16_t* aData)
+{
+  AssertIsOnMainThread();
+
+  MOZ_ASSERT((strcmp(aTopic, DOM_WINDOW_FROZEN_TOPIC) == 0) ||
+             (strcmp(aTopic, DOM_WINDOW_DESTROYED_TOPIC) == 0));
+
+  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(mGlobal);
+  if (SameCOMIdentity(aSubject, window)) {
+    ContinueConsumeBody(NS_BINDING_ABORTED, 0, nullptr);
+  }
+
+  return NS_OK;
+}
+
+template <class Derived>
+NS_IMPL_ADDREF(FetchBodyConsumer<Derived>)
+
+template <class Derived>
+NS_IMPL_RELEASE(FetchBodyConsumer<Derived>)
+
+template <class Derived>
+NS_IMPL_QUERY_INTERFACE(FetchBodyConsumer<Derived>,
+                        nsIObserver,
+                        nsISupportsWeakReference)
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/FetchConsumer.h b/dom/fetch/FetchConsumer.h
new file mode 100644
index 0000000000..a7509a0ae5
--- /dev/null
+++ b/dom/fetch/FetchConsumer.h
@@ -0,0 +1,128 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_FetchConsumer_h
+#define mozilla_dom_FetchConsumer_h
+
+#include "Fetch.h"
+#include "nsIObserver.h"
+#include "nsWeakReference.h"
+#include "mozilla/dom/MutableBlobStorage.h"
+
+class nsIThread;
+
+namespace mozilla {
+namespace dom {
+
+class Promise;
+
+namespace workers {
+class WorkerPrivate;
+class WorkerHolder;
+}
+
+template <class Derived> class FetchBody;
+
+// FetchBody is not thread-safe but we need to move it around threads.
+// In order to keep it alive all the time, we use a WorkerHolder, if created on
+// workers, plus a this consumer.
+template <class Derived>
+class FetchBodyConsumer final : public nsIObserver
+                              , public nsSupportsWeakReference
+{
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  static already_AddRefed<Promise>
+  Create(nsIGlobalObject* aGlobal,
+         FetchBody<Derived>* aBody,
+         FetchConsumeType aType,
+         ErrorResult& aRv);
+
+  void
+  ReleaseObject();
+
+  void
+  BeginConsumeBodyMainThread();
+
+  void
+  ContinueConsumeBody(nsresult aStatus, uint32_t aLength, uint8_t* aResult);
+
+  void
+  ContinueConsumeBlobBody(BlobImpl* aBlobImpl);
+
+  void
+  ShutDownMainThreadConsuming();
+
+  workers::WorkerPrivate*
+  GetWorkerPrivate() const
+  {
+    return mWorkerPrivate;
+  }
+
+  void
+  NullifyConsumeBodyPump()
+  {
+    mShuttingDown = true;
+    mConsumeBodyPump = nullptr;
+  }
+
+private:
+  FetchBodyConsumer(nsIGlobalObject* aGlobalObject,
+                    workers::WorkerPrivate* aWorkerPrivate,
+                    FetchBody<Derived>* aBody,
+                    nsIInputStream* aBodyStream,
+                    Promise* aPromise,
+                    FetchConsumeType aType);
+
+  ~FetchBodyConsumer();
+
+  void
+  AssertIsOnTargetThread() const;
+
+  bool
+  RegisterWorkerHolder();
+
+  nsCOMPtr<nsIThread> mTargetThread;
+
+#ifdef DEBUG
+  // This is used only to check if the body has been correctly consumed.
+  RefPtr<FetchBody<Derived>> mBody;
+#endif
+
+  nsCOMPtr<nsIInputStream> mBodyStream;
+  MutableBlobStorage::MutableBlobStorageType mBlobStorageType;
+  nsCString mBodyMimeType;
+
+  // Set when consuming the body is attempted on a worker.
+  // Unset when consumption is done/aborted.
+  // This WorkerHolder keeps alive the consumer via a cycle.
+  UniquePtr<workers::WorkerHolder> mWorkerHolder;
+
+  nsCOMPtr<nsIGlobalObject> mGlobal;
+
+  // Always set whenever the FetchBodyConsumer is created on the worker thread.
+  workers::WorkerPrivate* mWorkerPrivate;
+
+  // Touched on the main-thread only.
+  nsCOMPtr<nsIInputStreamPump> mConsumeBodyPump;
+
+  // Only ever set once, always on target thread.
+  FetchConsumeType mConsumeType;
+  RefPtr<Promise> mConsumePromise;
+
+  // touched only on the target thread.
+  bool mBodyConsumed;
+
+  // touched only on the main-thread.
+  bool mShuttingDown;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_FetchConsumer_h
diff --git a/dom/fetch/FetchDriver.cpp b/dom/fetch/FetchDriver.cpp
new file mode 100644
index 0000000000..aac79b8290
--- /dev/null
+++ b/dom/fetch/FetchDriver.cpp
@@ -0,0 +1,938 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/DebugOnly.h"
+#include "mozilla/dom/FetchDriver.h"
+
+#include "nsIAsyncVerifyRedirectCallback.h"
+#include "nsIDocument.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsIHttpChannel.h"
+#include "nsIHttpChannelInternal.h"
+#include "nsIHttpHeaderVisitor.h"
+#include "nsIScriptSecurityManager.h"
+#include "nsIThreadRetargetableRequest.h"
+#include "nsIUploadChannel2.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIPipe.h"
+
+#include "nsContentPolicyUtils.h"
+#include "nsDataHandler.h"
+#include "nsHostObjectProtocolHandler.h"
+#include "nsNetUtil.h"
+#include "nsPrintfCString.h"
+#include "nsStreamUtils.h"
+#include "nsStringStream.h"
+#include "nsHttpChannel.h"
+
+#include "mozilla/dom/File.h"
+#include "mozilla/dom/workers/Workers.h"
+#include "mozilla/ipc/PBackgroundSharedTypes.h"
+#include "mozilla/Unused.h"
+
+#include "Fetch.h"
+#include "InternalRequest.h"
+#include "InternalResponse.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_ISUPPORTS(FetchDriver,
+                  nsIStreamListener, nsIChannelEventSink, nsIInterfaceRequestor,
+                  nsIThreadRetargetableStreamListener)
+
+FetchDriver::FetchDriver(InternalRequest* aRequest, nsIPrincipal* aPrincipal,
+                         nsILoadGroup* aLoadGroup)
+  : mPrincipal(aPrincipal)
+  , mLoadGroup(aLoadGroup)
+  , mRequest(aRequest)
+#ifdef DEBUG
+  , mResponseAvailableCalled(false)
+  , mFetchCalled(false)
+#endif
+{
+  MOZ_ASSERT(aRequest);
+  MOZ_ASSERT(aPrincipal);
+}
+
+FetchDriver::~FetchDriver()
+{
+  // We assert this since even on failures, we should call
+  // FailWithNetworkError().
+  MOZ_ASSERT(mResponseAvailableCalled);
+}
+
+nsresult
+FetchDriver::Fetch(FetchDriverObserver* aObserver)
+{
+  workers::AssertIsOnMainThread();
+#ifdef DEBUG
+  MOZ_ASSERT(!mFetchCalled);
+  mFetchCalled = true;
+#endif
+
+  mObserver = aObserver;
+
+  Telemetry::Accumulate(Telemetry::SERVICE_WORKER_REQUEST_PASSTHROUGH,
+                        mRequest->WasCreatedByFetchEvent());
+
+  // FIXME(nsm): Deal with HSTS.
+
+  MOZ_RELEASE_ASSERT(!mRequest->IsSynchronous(),
+                     "Synchronous fetch not supported");
+
+
+  UniquePtr<mozilla::ipc::PrincipalInfo> principalInfo(new mozilla::ipc::PrincipalInfo());
+  nsresult rv = PrincipalToPrincipalInfo(mPrincipal, principalInfo.get());
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  mRequest->SetPrincipalInfo(Move(principalInfo));
+  if (NS_FAILED(HttpFetch())) {
+    FailWithNetworkError();
+  }
+
+  // Any failure is handled by FailWithNetworkError notifying the aObserver.
+  return NS_OK;
+}
+
+// This function implements the "HTTP Fetch" algorithm from the Fetch spec.
+// Functionality is often split between here, the CORS listener proxy and the
+// Necko HTTP implementation.
+nsresult
+FetchDriver::HttpFetch()
+{
+  // Step 1. "Let response be null."
+  mResponse = nullptr;
+  nsresult rv;
+
+  nsCOMPtr<nsIIOService> ios = do_GetIOService(&rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoCString url;
+  mRequest->GetURL(url);
+  nsCOMPtr<nsIURI> uri;
+  rv = NS_NewURI(getter_AddRefs(uri),
+                          url,
+                          nullptr,
+                          nullptr,
+                          ios);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Unsafe requests aren't allowed with when using no-core mode.
+  if (mRequest->Mode() == RequestMode::No_cors &&
+      mRequest->UnsafeRequest() &&
+      (!mRequest->HasSimpleMethod() ||
+       !mRequest->Headers()->HasOnlySimpleHeaders())) {
+    MOZ_ASSERT(false, "The API should have caught this");
+    return NS_ERROR_DOM_BAD_URI;
+  }
+
+  // non-GET requests aren't allowed for blob.
+  if (IsBlobURI(uri)) {
+    nsAutoCString method;
+    mRequest->GetMethod(method);
+    if (!method.EqualsLiteral("GET")) {
+      return NS_ERROR_DOM_NETWORK_ERR;
+    }
+  }
+
+  // Step 2 deals with letting ServiceWorkers intercept requests. This is
+  // handled by Necko after the channel is opened.
+  // FIXME(nsm): Bug 1119026: The channel's skip service worker flag should be
+  // set based on the Request's flag.
+
+  // Step 3.1 "If the CORS preflight flag is set and one of these conditions is
+  // true..." is handled by the CORS proxy.
+  //
+  // Step 3.2 "Set request's skip service worker flag." This isn't required
+  // since Necko will fall back to the network if the ServiceWorker does not
+  // respond with a valid Response.
+  //
+  // NS_StartCORSPreflight() will automatically kick off the original request
+  // if it succeeds, so we need to have everything setup for the original
+  // request too.
+
+  // Step 3.3 "Let credentials flag be set if one of
+  //  - request's credentials mode is "include"
+  //  - request's credentials mode is "same-origin" and either the CORS flag
+  //    is unset or response tainting is "opaque"
+  // is true, and unset otherwise."
+
+  // Set skip serviceworker flag.
+  // While the spec also gates on the client being a ServiceWorker, we can't
+  // infer that here. Instead we rely on callers to set the flag correctly.
+  const nsLoadFlags bypassFlag = mRequest->SkipServiceWorker() ?
+                                 nsIChannel::LOAD_BYPASS_SERVICE_WORKER : 0;
+
+  nsSecurityFlags secFlags = nsILoadInfo::SEC_ABOUT_BLANK_INHERITS;
+  if (mRequest->Mode() == RequestMode::Cors) {
+    secFlags |= nsILoadInfo::SEC_REQUIRE_CORS_DATA_INHERITS;
+  } else if (mRequest->Mode() == RequestMode::Same_origin ||
+             mRequest->Mode() == RequestMode::Navigate) {
+    secFlags |= nsILoadInfo::SEC_REQUIRE_SAME_ORIGIN_DATA_INHERITS;
+  } else if (mRequest->Mode() == RequestMode::No_cors) {
+    secFlags |= nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_INHERITS;
+  } else {
+    MOZ_ASSERT_UNREACHABLE("Unexpected request mode!");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (mRequest->GetRedirectMode() != RequestRedirect::Follow) {
+    secFlags |= nsILoadInfo::SEC_DONT_FOLLOW_REDIRECTS;
+  }
+
+  // This is handles the use credentials flag in "HTTP
+  // network or cache fetch" in the spec and decides whether to transmit
+  // cookies and other identifying information.
+  if (mRequest->GetCredentialsMode() == RequestCredentials::Include) {
+    secFlags |= nsILoadInfo::SEC_COOKIES_INCLUDE;
+  } else if (mRequest->GetCredentialsMode() == RequestCredentials::Omit) {
+    secFlags |= nsILoadInfo::SEC_COOKIES_OMIT;
+  } else if (mRequest->GetCredentialsMode() == RequestCredentials::Same_origin) {
+    secFlags |= nsILoadInfo::SEC_COOKIES_SAME_ORIGIN;
+  } else {
+    MOZ_ASSERT_UNREACHABLE("Unexpected credentials mode!");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  // From here on we create a channel and set its properties with the
+  // information from the InternalRequest. This is an implementation detail.
+  MOZ_ASSERT(mLoadGroup);
+  nsCOMPtr<nsIChannel> chan;
+
+  nsLoadFlags loadFlags = nsIRequest::LOAD_NORMAL |
+    bypassFlag | nsIChannel::LOAD_CLASSIFY_URI;
+  if (mDocument) {
+    MOZ_ASSERT(mDocument->NodePrincipal() == mPrincipal);
+    rv = NS_NewChannel(getter_AddRefs(chan),
+                       uri,
+                       mDocument,
+                       secFlags,
+                       mRequest->ContentPolicyType(),
+                       mLoadGroup,
+                       nullptr, /* aCallbacks */
+                       loadFlags,
+                       ios);
+  } else {
+    rv = NS_NewChannel(getter_AddRefs(chan),
+                       uri,
+                       mPrincipal,
+                       secFlags,
+                       mRequest->ContentPolicyType(),
+                       mLoadGroup,
+                       nullptr, /* aCallbacks */
+                       loadFlags,
+                       ios);
+  }
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  mLoadGroup = nullptr;
+
+  // Insert ourselves into the notification callbacks chain so we can set
+  // headers on redirects.
+#ifdef DEBUG
+  {
+    nsCOMPtr<nsIInterfaceRequestor> notificationCallbacks;
+    chan->GetNotificationCallbacks(getter_AddRefs(notificationCallbacks));
+    MOZ_ASSERT(!notificationCallbacks);
+  }
+#endif
+  chan->SetNotificationCallbacks(this);
+
+  // Step 3.5 begins "HTTP network or cache fetch".
+  // HTTP network or cache fetch
+  // ---------------------------
+  // Step 1 "Let HTTPRequest..." The channel is the HTTPRequest.
+  nsCOMPtr<nsIHttpChannel> httpChan = do_QueryInterface(chan);
+  if (httpChan) {
+    // Copy the method.
+    nsAutoCString method;
+    mRequest->GetMethod(method);
+    rv = httpChan->SetRequestMethod(method);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    // Set the same headers.
+    SetRequestHeaders(httpChan);
+
+    // Step 2. Set the referrer.
+    nsAutoString referrer;
+    mRequest->GetReferrer(referrer);
+
+    // The Referrer Policy in Request can be used to override a referrer policy
+    // associated with an environment settings object.
+    // If there's no Referrer Policy in the request, it should be inherited
+    // from environment.
+    ReferrerPolicy referrerPolicy = mRequest->ReferrerPolicy_();
+    net::ReferrerPolicy net_referrerPolicy = mRequest->GetEnvironmentReferrerPolicy();
+    switch (referrerPolicy) {
+    case ReferrerPolicy::_empty:
+      break;
+    case ReferrerPolicy::No_referrer:
+      net_referrerPolicy = net::RP_No_Referrer;
+      break;
+    case ReferrerPolicy::No_referrer_when_downgrade:
+      net_referrerPolicy = net::RP_No_Referrer_When_Downgrade;
+      break;
+    case ReferrerPolicy::Origin:
+      net_referrerPolicy = net::RP_Origin;
+      break;
+    case ReferrerPolicy::Origin_when_cross_origin:
+      net_referrerPolicy = net::RP_Origin_When_Crossorigin;
+      break;
+    case ReferrerPolicy::Unsafe_url:
+      net_referrerPolicy = net::RP_Unsafe_URL;
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid ReferrerPolicy enum value?");
+      break;
+    }
+    if (referrer.EqualsLiteral(kFETCH_CLIENT_REFERRER_STR)) {
+      rv = nsContentUtils::SetFetchReferrerURIWithPolicy(mPrincipal,
+                                                         mDocument,
+                                                         httpChan,
+                                                         net_referrerPolicy);
+      NS_ENSURE_SUCCESS(rv, rv);
+    } else if (referrer.IsEmpty()) {
+      rv = httpChan->SetReferrerWithPolicy(nullptr, net::RP_No_Referrer);
+      NS_ENSURE_SUCCESS(rv, rv);
+    } else {
+      // From "Determine request's Referrer" step 3
+      // "If request's referrer is a URL, let referrerSource be request's
+      // referrer."
+      nsCOMPtr<nsIURI> referrerURI;
+      rv = NS_NewURI(getter_AddRefs(referrerURI), referrer, nullptr, nullptr);
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      rv =
+        httpChan->SetReferrerWithPolicy(referrerURI,
+                                        referrerPolicy == ReferrerPolicy::_empty ?
+                                          mRequest->GetEnvironmentReferrerPolicy() :
+                                          net_referrerPolicy);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+
+    // Bug 1120722 - Authorization will be handled later.
+    // Auth may require prompting, we don't support it yet.
+    // The next patch in this same bug prevents this from aborting the request.
+    // Credentials checks for CORS are handled by nsCORSListenerProxy,
+
+    nsCOMPtr<nsIHttpChannelInternal> internalChan = do_QueryInterface(httpChan);
+
+    // Conversion between enumerations is safe due to static asserts in
+    // dom/workers/ServiceWorkerManager.cpp
+    internalChan->SetCorsMode(static_cast<uint32_t>(mRequest->Mode()));
+    internalChan->SetRedirectMode(static_cast<uint32_t>(mRequest->GetRedirectMode()));
+    mRequest->MaybeSkipCacheIfPerformingRevalidation();
+    internalChan->SetFetchCacheMode(static_cast<uint32_t>(mRequest->GetCacheMode()));
+    internalChan->SetIntegrityMetadata(mRequest->GetIntegrity());
+  }
+
+  // Step 5. Proxy authentication will be handled by Necko.
+
+  // Continue setting up 'HTTPRequest'. Content-Type and body data.
+  nsCOMPtr<nsIUploadChannel2> uploadChan = do_QueryInterface(chan);
+  if (uploadChan) {
+    nsAutoCString contentType;
+    ErrorResult result;
+    mRequest->Headers()->GetFirst(NS_LITERAL_CSTRING("content-type"), contentType, result);
+    // We don't actually expect "result" to have failed here: that only happens
+    // for invalid header names.  But if for some reason it did, just propagate
+    // it out.
+    if (result.Failed()) {
+      return result.StealNSResult();
+    }
+
+    // Now contentType is the header that was set in mRequest->Headers(), or a
+    // void string if no header was set.
+#ifdef DEBUG
+    bool hasContentTypeHeader =
+      mRequest->Headers()->Has(NS_LITERAL_CSTRING("content-type"), result);
+    MOZ_ASSERT(!result.Failed());
+    MOZ_ASSERT_IF(!hasContentTypeHeader, contentType.IsVoid());
+#endif // DEBUG
+
+    nsCOMPtr<nsIInputStream> bodyStream;
+    mRequest->GetBody(getter_AddRefs(bodyStream));
+    if (bodyStream) {
+      nsAutoCString method;
+      mRequest->GetMethod(method);
+      rv = uploadChan->ExplicitSetUploadStream(bodyStream, contentType, -1, method, false /* aStreamHasHeaders */);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+  }
+
+  // If preflight is required, start a "CORS preflight fetch"
+  // https://fetch.spec.whatwg.org/#cors-preflight-fetch-0. All the
+  // implementation is handled by the http channel calling into
+  // nsCORSListenerProxy. We just inform it which unsafe headers are included
+  // in the request.
+  if (mRequest->Mode() == RequestMode::Cors) {
+    AutoTArray<nsCString, 5> unsafeHeaders;
+    mRequest->Headers()->GetUnsafeHeaders(unsafeHeaders);
+    nsCOMPtr<nsILoadInfo> loadInfo = chan->GetLoadInfo();
+    loadInfo->SetCorsPreflightInfo(unsafeHeaders, false);
+  }
+
+  rv = chan->AsyncOpen2(this);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Step 4 onwards of "HTTP Fetch" is handled internally by Necko.
+  return NS_OK;
+}
+already_AddRefed<InternalResponse>
+FetchDriver::BeginAndGetFilteredResponse(InternalResponse* aResponse,
+                                         bool aFoundOpaqueRedirect)
+{
+  MOZ_ASSERT(aResponse);
+  AutoTArray<nsCString, 4> reqURLList;
+  mRequest->GetURLListWithoutFragment(reqURLList);
+  MOZ_ASSERT(!reqURLList.IsEmpty());
+  aResponse->SetURLList(reqURLList);
+  RefPtr<InternalResponse> filteredResponse;
+  if (aFoundOpaqueRedirect) {
+    filteredResponse = aResponse->OpaqueRedirectResponse();
+  } else {
+    switch (mRequest->GetResponseTainting()) {
+      case LoadTainting::Basic:
+        filteredResponse = aResponse->BasicResponse();
+        break;
+      case LoadTainting::CORS:
+        filteredResponse = aResponse->CORSResponse();
+        break;
+      case LoadTainting::Opaque:
+        filteredResponse = aResponse->OpaqueResponse();
+        break;
+      default:
+        MOZ_CRASH("Unexpected case");
+    }
+  }
+
+  MOZ_ASSERT(filteredResponse);
+  MOZ_ASSERT(mObserver);
+  if (filteredResponse->Type() == ResponseType::Error ||
+      mRequest->GetIntegrity().IsEmpty()) {
+    mObserver->OnResponseAvailable(filteredResponse);
+  #ifdef DEBUG
+    mResponseAvailableCalled = true;
+  #endif
+  }
+
+  return filteredResponse.forget();
+}
+
+void
+FetchDriver::FailWithNetworkError()
+{
+  workers::AssertIsOnMainThread();
+  RefPtr<InternalResponse> error = InternalResponse::NetworkError();
+  if (mObserver) {
+    mObserver->OnResponseAvailable(error);
+#ifdef DEBUG
+    mResponseAvailableCalled = true;
+#endif
+    mObserver->OnResponseEnd();
+    mObserver = nullptr;
+  }
+}
+
+namespace {
+class FillResponseHeaders final : public nsIHttpHeaderVisitor {
+  InternalResponse* mResponse;
+
+  ~FillResponseHeaders()
+  { }
+public:
+  NS_DECL_ISUPPORTS
+
+  explicit FillResponseHeaders(InternalResponse* aResponse)
+    : mResponse(aResponse)
+  {
+  }
+
+  NS_IMETHOD
+  VisitHeader(const nsACString & aHeader, const nsACString & aValue) override
+  {
+    ErrorResult result;
+    mResponse->Headers()->Append(aHeader, aValue, result);
+    if (result.Failed()) {
+      NS_WARNING(nsPrintfCString("Fetch ignoring illegal header - '%s': '%s'",
+                                 PromiseFlatCString(aHeader).get(),
+                                 PromiseFlatCString(aValue).get()).get());
+      result.SuppressException();
+    }
+    return NS_OK;
+  }
+};
+
+NS_IMPL_ISUPPORTS(FillResponseHeaders, nsIHttpHeaderVisitor)
+} // namespace
+
+NS_IMETHODIMP
+FetchDriver::OnStartRequest(nsIRequest* aRequest,
+                            nsISupports* aContext)
+{
+  workers::AssertIsOnMainThread();
+
+  // Note, this can be called multiple times if we are doing an opaqueredirect.
+  // In that case we will get a simulated OnStartRequest() and then the real
+  // channel will call in with an errored OnStartRequest().
+
+  nsresult rv;
+  aRequest->GetStatus(&rv);
+  if (NS_FAILED(rv)) {
+    FailWithNetworkError();
+    return rv;
+  }
+
+  // We should only get to the following code once.
+  MOZ_ASSERT(!mPipeOutputStream);
+  MOZ_ASSERT(mObserver);
+
+  RefPtr<InternalResponse> response;
+  nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
+  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aRequest);
+
+  // On a successful redirect we perform the following substeps of HTTP Fetch,
+  // step 5, "redirect status", step 11.
+
+  bool foundOpaqueRedirect = false;
+
+  int64_t contentLength = InternalResponse::UNKNOWN_BODY_SIZE;
+  rv = channel->GetContentLength(&contentLength);
+  MOZ_ASSERT_IF(NS_FAILED(rv), contentLength == InternalResponse::UNKNOWN_BODY_SIZE);
+
+  if (httpChannel) {
+    uint32_t responseStatus;
+    httpChannel->GetResponseStatus(&responseStatus);
+
+    if (mozilla::net::nsHttpChannel::IsRedirectStatus(responseStatus)) {
+      if (mRequest->GetRedirectMode() == RequestRedirect::Error) {
+        FailWithNetworkError();
+        return NS_BINDING_FAILED;
+      }
+      if (mRequest->GetRedirectMode() == RequestRedirect::Manual) {
+        foundOpaqueRedirect = true;
+      }
+    }
+
+    nsAutoCString statusText;
+    httpChannel->GetResponseStatusText(statusText);
+
+    response = new InternalResponse(responseStatus, statusText);
+
+    RefPtr<FillResponseHeaders> visitor = new FillResponseHeaders(response);
+    rv = httpChannel->VisitResponseHeaders(visitor);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      NS_WARNING("Failed to visit all headers.");
+    }
+
+    // If Content-Encoding or Transfer-Encoding headers are set, then the actual
+    // Content-Length (which refer to the decoded data) is obscured behind the encodings.
+    ErrorResult result;
+    if (response->Headers()->Has(NS_LITERAL_CSTRING("content-encoding"), result) ||
+        response->Headers()->Has(NS_LITERAL_CSTRING("transfer-encoding"), result)) {
+      NS_WARNING("Cannot know response Content-Length due to presence of Content-Encoding "
+                 "or Transfer-Encoding headers.");
+      contentLength = InternalResponse::UNKNOWN_BODY_SIZE;
+    }
+    MOZ_ASSERT(!result.Failed());
+  } else {
+    response = new InternalResponse(200, NS_LITERAL_CSTRING("OK"));
+
+    ErrorResult result;
+    nsAutoCString contentType;
+    rv = channel->GetContentType(contentType);
+    if (NS_SUCCEEDED(rv) && !contentType.IsEmpty()) {
+      nsAutoCString contentCharset;
+      channel->GetContentCharset(contentCharset);
+      if (NS_SUCCEEDED(rv) && !contentCharset.IsEmpty()) {
+        contentType += NS_LITERAL_CSTRING(";charset=") + contentCharset;
+      }
+
+      response->Headers()->Append(NS_LITERAL_CSTRING("Content-Type"),
+                                  contentType,
+                                  result);
+      MOZ_ASSERT(!result.Failed());
+    }
+
+    if (contentLength > 0) {
+      nsAutoCString contentLenStr;
+      contentLenStr.AppendInt(contentLength);
+      response->Headers()->Append(NS_LITERAL_CSTRING("Content-Length"),
+                                  contentLenStr,
+                                  result);
+      MOZ_ASSERT(!result.Failed());
+    }
+  }
+
+  // We open a pipe so that we can immediately set the pipe's read end as the
+  // response's body. Setting the segment size to UINT32_MAX means that the
+  // pipe has infinite space. The nsIChannel will continue to buffer data in
+  // xpcom events even if we block on a fixed size pipe.  It might be possible
+  // to suspend the channel and then resume when there is space available, but
+  // for now use an infinite pipe to avoid blocking.
+  nsCOMPtr<nsIInputStream> pipeInputStream;
+  rv = NS_NewPipe(getter_AddRefs(pipeInputStream),
+                  getter_AddRefs(mPipeOutputStream),
+                  0, /* default segment size */
+                  UINT32_MAX /* infinite pipe */,
+                  true /* non-blocking input, otherwise you deadlock */,
+                  false /* blocking output, since the pipe is 'in'finite */ );
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    FailWithNetworkError();
+    // Cancel request.
+    return rv;
+  }
+  response->SetBody(pipeInputStream, contentLength);
+
+  response->InitChannelInfo(channel);
+
+  nsCOMPtr<nsIURI> channelURI;
+  rv = channel->GetURI(getter_AddRefs(channelURI));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    FailWithNetworkError();
+    // Cancel request.
+    return rv;
+  }
+
+  nsCOMPtr<nsILoadInfo> loadInfo;
+  rv = channel->GetLoadInfo(getter_AddRefs(loadInfo));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    FailWithNetworkError();
+    return rv;
+  }
+
+  // Propagate any tainting from the channel back to our response here.  This
+  // step is not reflected in the spec because the spec is written such that
+  // FetchEvent.respondWith() just passes the already-tainted Response back to
+  // the outer fetch().  In gecko, however, we serialize the Response through
+  // the channel and must regenerate the tainting from the channel in the
+  // interception case.
+  mRequest->MaybeIncreaseResponseTainting(loadInfo->GetTainting());
+
+  // Resolves fetch() promise which may trigger code running in a worker.  Make
+  // sure the Response is fully initialized before calling this.
+  mResponse = BeginAndGetFilteredResponse(response, foundOpaqueRedirect);
+
+  // From "Main Fetch" step 17: SRI-part1.
+  if (mResponse->Type() != ResponseType::Error &&
+      !mRequest->GetIntegrity().IsEmpty() &&
+      mSRIMetadata.IsEmpty()) {
+    nsIConsoleReportCollector* aReporter = nullptr;
+    if (mObserver) {
+      aReporter = mObserver->GetReporter();
+    }
+
+    nsAutoCString sourceUri;
+    if (mDocument && mDocument->GetDocumentURI()) {
+      mDocument->GetDocumentURI()->GetAsciiSpec(sourceUri);
+    } else if (!mWorkerScript.IsEmpty()) {
+      sourceUri.Assign(mWorkerScript);
+    }
+    SRICheck::IntegrityMetadata(mRequest->GetIntegrity(), sourceUri,
+                                aReporter, &mSRIMetadata);
+    mSRIDataVerifier = new SRICheckDataVerifier(mSRIMetadata, sourceUri,
+                                                aReporter);
+
+    // Do not retarget off main thread when using SRI API.
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIEventTarget> sts = do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID, &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    FailWithNetworkError();
+    // Cancel request.
+    return rv;
+  }
+
+  // Try to retarget off main thread.
+  if (nsCOMPtr<nsIThreadRetargetableRequest> rr = do_QueryInterface(aRequest)) {
+    Unused << NS_WARN_IF(NS_FAILED(rr->RetargetDeliveryTo(sts)));
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+FetchDriver::OnDataAvailable(nsIRequest* aRequest,
+                             nsISupports* aContext,
+                             nsIInputStream* aInputStream,
+                             uint64_t aOffset,
+                             uint32_t aCount)
+{
+  // NB: This can be called on any thread!  But we're guaranteed that it is
+  // called between OnStartRequest and OnStopRequest, so we don't need to worry
+  // about races.
+
+  uint32_t aRead;
+  MOZ_ASSERT(mResponse);
+  MOZ_ASSERT(mPipeOutputStream);
+
+  // From "Main Fetch" step 17: SRI-part2.
+  if (mResponse->Type() != ResponseType::Error &&
+      !mRequest->GetIntegrity().IsEmpty()) {
+    MOZ_ASSERT(mSRIDataVerifier);
+
+    uint32_t aWrite;
+    nsTArray<uint8_t> buffer;
+    nsresult rv;
+    buffer.SetCapacity(aCount);
+    while (aCount > 0) {
+      rv = aInputStream->Read(reinterpret_cast<char*>(buffer.Elements()),
+                              aCount, &aRead);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+
+      rv = mSRIDataVerifier->Update(aRead, (uint8_t*)buffer.Elements());
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      while (aRead > 0) {
+        rv = mPipeOutputStream->Write(reinterpret_cast<char*>(buffer.Elements()),
+                                      aRead, &aWrite);
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+          return rv;
+        }
+
+        if (aRead < aWrite) {
+          return NS_ERROR_FAILURE;
+        }
+
+        aRead -= aWrite;
+      }
+
+
+      aCount -= aWrite;
+    }
+
+    return NS_OK;
+  }
+
+  nsresult rv = aInputStream->ReadSegments(NS_CopySegmentToStream,
+                                           mPipeOutputStream,
+                                           aCount, &aRead);
+  return rv;
+}
+
+NS_IMETHODIMP
+FetchDriver::OnStopRequest(nsIRequest* aRequest,
+                           nsISupports* aContext,
+                           nsresult aStatusCode)
+{
+  workers::AssertIsOnMainThread();
+  if (NS_FAILED(aStatusCode)) {
+    nsCOMPtr<nsIAsyncOutputStream> outputStream = do_QueryInterface(mPipeOutputStream);
+    if (outputStream) {
+      outputStream->CloseWithStatus(NS_BINDING_FAILED);
+    }
+
+    // We proceed as usual here, since we've already created a successful response
+    // from OnStartRequest.
+  } else {
+    MOZ_ASSERT(mResponse);
+    MOZ_ASSERT(!mResponse->IsError());
+
+    // From "Main Fetch" step 17: SRI-part3.
+    if (mResponse->Type() != ResponseType::Error &&
+        !mRequest->GetIntegrity().IsEmpty()) {
+      MOZ_ASSERT(mSRIDataVerifier);
+
+      nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
+
+      nsIConsoleReportCollector* aReporter = nullptr;
+      if (mObserver) {
+        aReporter = mObserver->GetReporter();
+      }
+
+      nsAutoCString sourceUri;
+      if (mDocument && mDocument->GetDocumentURI()) {
+        mDocument->GetDocumentURI()->GetAsciiSpec(sourceUri);
+      } else if (!mWorkerScript.IsEmpty()) {
+        sourceUri.Assign(mWorkerScript);
+      }
+      nsresult rv = mSRIDataVerifier->Verify(mSRIMetadata, channel, sourceUri,
+                                             aReporter);
+      if (NS_FAILED(rv)) {
+        FailWithNetworkError();
+        // Cancel request.
+        return rv;
+      }
+    }
+
+    if (mPipeOutputStream) {
+      mPipeOutputStream->Close();
+    }
+  }
+
+  if (mObserver) {
+    if (mResponse->Type() != ResponseType::Error &&
+        !mRequest->GetIntegrity().IsEmpty()) {
+      //From "Main Fetch" step 23: Process response.
+      MOZ_ASSERT(mResponse);
+      mObserver->OnResponseAvailable(mResponse);
+      #ifdef DEBUG
+        mResponseAvailableCalled = true;
+      #endif
+    }
+
+    mObserver->OnResponseEnd();
+    mObserver = nullptr;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+FetchDriver::AsyncOnChannelRedirect(nsIChannel* aOldChannel,
+                                    nsIChannel* aNewChannel,
+                                    uint32_t aFlags,
+                                    nsIAsyncVerifyRedirectCallback *aCallback)
+{
+  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aNewChannel);
+  if (httpChannel) {
+    SetRequestHeaders(httpChannel);
+  }
+
+  nsCOMPtr<nsIHttpChannel> oldHttpChannel = do_QueryInterface(aOldChannel);
+  nsAutoCString tRPHeaderCValue;
+  if (oldHttpChannel) {
+    oldHttpChannel->GetResponseHeader(NS_LITERAL_CSTRING("referrer-policy"),
+                                      tRPHeaderCValue);
+  }
+
+  // "HTTP-redirect fetch": step 14 "Append locationURL to request's URL list."
+  nsCOMPtr<nsIURI> uri;
+  MOZ_ALWAYS_SUCCEEDS(aNewChannel->GetURI(getter_AddRefs(uri)));
+
+  nsCOMPtr<nsIURI> uriClone;
+  nsresult rv = uri->CloneIgnoringRef(getter_AddRefs(uriClone));
+  if(NS_WARN_IF(NS_FAILED(rv))){
+    return rv;
+  }
+  nsCString spec;
+  rv = uriClone->GetSpec(spec);
+  if(NS_WARN_IF(NS_FAILED(rv))){
+    return rv;
+  }
+  nsCString fragment;
+  rv = uri->GetRef(fragment);
+  if(NS_WARN_IF(NS_FAILED(rv))){
+    return rv;
+  }
+
+  mRequest->AddURL(spec, fragment);
+  NS_ConvertUTF8toUTF16 tRPHeaderValue(tRPHeaderCValue);
+  // updates request’s associated referrer policy according to the
+  // Referrer-Policy header (if any).
+  if (!tRPHeaderValue.IsEmpty()) {
+    net::ReferrerPolicy net_referrerPolicy =
+      nsContentUtils::GetReferrerPolicyFromHeader(tRPHeaderValue);
+    if (net_referrerPolicy != net::RP_Unset) {
+      ReferrerPolicy referrerPolicy = mRequest->ReferrerPolicy_();
+      switch (net_referrerPolicy) {
+        case net::RP_No_Referrer:
+          referrerPolicy = ReferrerPolicy::No_referrer;
+          break;
+        case net::RP_No_Referrer_When_Downgrade:
+          referrerPolicy = ReferrerPolicy::No_referrer_when_downgrade;
+          break;
+        case net::RP_Origin:
+          referrerPolicy = ReferrerPolicy::Origin;
+          break;
+        case net::RP_Origin_When_Crossorigin:
+          referrerPolicy = ReferrerPolicy::Origin_when_cross_origin;
+          break;
+        case net::RP_Unsafe_URL:
+          referrerPolicy = ReferrerPolicy::Unsafe_url;
+          break;
+        default:
+          MOZ_ASSERT_UNREACHABLE("Invalid ReferrerPolicy value");
+          break;
+      }
+
+      mRequest->SetReferrerPolicy(referrerPolicy);
+    }
+  }
+
+  aCallback->OnRedirectVerifyCallback(NS_OK);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+FetchDriver::CheckListenerChain()
+{
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+FetchDriver::GetInterface(const nsIID& aIID, void **aResult)
+{
+  if (aIID.Equals(NS_GET_IID(nsIChannelEventSink))) {
+    *aResult = static_cast<nsIChannelEventSink*>(this);
+    NS_ADDREF_THIS();
+    return NS_OK;
+  }
+  if (aIID.Equals(NS_GET_IID(nsIStreamListener))) {
+    *aResult = static_cast<nsIStreamListener*>(this);
+    NS_ADDREF_THIS();
+    return NS_OK;
+  }
+  if (aIID.Equals(NS_GET_IID(nsIRequestObserver))) {
+    *aResult = static_cast<nsIRequestObserver*>(this);
+    NS_ADDREF_THIS();
+    return NS_OK;
+  }
+
+  return QueryInterface(aIID, aResult);
+}
+
+void
+FetchDriver::SetDocument(nsIDocument* aDocument)
+{
+  // Cannot set document after Fetch() has been called.
+  MOZ_ASSERT(!mFetchCalled);
+  mDocument = aDocument;
+}
+
+void
+FetchDriver::SetRequestHeaders(nsIHttpChannel* aChannel) const
+{
+  MOZ_ASSERT(aChannel);
+
+  AutoTArray<InternalHeaders::Entry, 5> headers;
+  mRequest->Headers()->GetEntries(headers);
+  bool hasAccept = false;
+  for (uint32_t i = 0; i < headers.Length(); ++i) {
+    if (!hasAccept && headers[i].mName.EqualsLiteral("accept")) {
+      hasAccept = true;
+    }
+    if (headers[i].mValue.IsEmpty()) {
+      aChannel->SetEmptyRequestHeader(headers[i].mName);
+    } else {
+      aChannel->SetRequestHeader(headers[i].mName, headers[i].mValue, false /* merge */);
+    }
+  }
+
+  if (!hasAccept) {
+    aChannel->SetRequestHeader(NS_LITERAL_CSTRING("accept"),
+                               NS_LITERAL_CSTRING("*/*"),
+                               false /* merge */);
+  }
+
+  if (mRequest->ForceOriginHeader()) {
+    nsAutoString origin;
+    if (NS_SUCCEEDED(nsContentUtils::GetUTFOrigin(mPrincipal, origin))) {
+      aChannel->SetRequestHeader(NS_LITERAL_CSTRING("origin"),
+                                 NS_ConvertUTF16toUTF8(origin),
+                                 false /* merge */);
+    }
+  }
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/FetchDriver.h b/dom/fetch/FetchDriver.h
new file mode 100644
index 0000000000..f74298a48c
--- /dev/null
+++ b/dom/fetch/FetchDriver.h
@@ -0,0 +1,136 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_FetchDriver_h
+#define mozilla_dom_FetchDriver_h
+
+#include "nsIChannelEventSink.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIStreamListener.h"
+#include "nsIThreadRetargetableStreamListener.h"
+#include "mozilla/ConsoleReportCollector.h"
+#include "mozilla/dom/SRIMetadata.h"
+#include "mozilla/RefPtr.h"
+
+#include "mozilla/DebugOnly.h"
+#include "mozilla/net/ReferrerPolicy.h"
+
+class nsIConsoleReportCollector;
+class nsIDocument;
+class nsIOutputStream;
+class nsILoadGroup;
+class nsIPrincipal;
+
+namespace mozilla {
+namespace dom {
+
+class InternalRequest;
+class InternalResponse;
+
+/**
+ * Provides callbacks to be called when response is available or on error.
+ * Implemenations usually resolve or reject the promise returned from fetch().
+ * The callbacks can be called synchronously or asynchronously from FetchDriver::Fetch.
+ */
+class FetchDriverObserver
+{
+public:
+  FetchDriverObserver() : mReporter(new ConsoleReportCollector())
+                        , mGotResponseAvailable(false)
+  { }
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(FetchDriverObserver);
+  void OnResponseAvailable(InternalResponse* aResponse)
+  {
+    MOZ_ASSERT(!mGotResponseAvailable);
+    mGotResponseAvailable = true;
+    OnResponseAvailableInternal(aResponse);
+  }
+  virtual void OnResponseEnd()
+  { };
+
+  nsIConsoleReportCollector* GetReporter() const
+  {
+    return mReporter;
+  }
+
+  virtual void FlushConsoleReport() = 0;
+protected:
+  virtual ~FetchDriverObserver()
+  { };
+
+  virtual void OnResponseAvailableInternal(InternalResponse* aResponse) = 0;
+
+  nsCOMPtr<nsIConsoleReportCollector> mReporter;
+private:
+  bool mGotResponseAvailable;
+};
+
+class FetchDriver final : public nsIStreamListener,
+                          public nsIChannelEventSink,
+                          public nsIInterfaceRequestor,
+                          public nsIThreadRetargetableStreamListener
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIREQUESTOBSERVER
+  NS_DECL_NSISTREAMLISTENER
+  NS_DECL_NSICHANNELEVENTSINK
+  NS_DECL_NSIINTERFACEREQUESTOR
+  NS_DECL_NSITHREADRETARGETABLESTREAMLISTENER
+
+  explicit FetchDriver(InternalRequest* aRequest, nsIPrincipal* aPrincipal,
+                       nsILoadGroup* aLoadGroup);
+  NS_IMETHOD Fetch(FetchDriverObserver* aObserver);
+
+  void
+  SetDocument(nsIDocument* aDocument);
+
+  void
+  SetWorkerScript(const nsACString& aWorkerScirpt)
+  {
+    MOZ_ASSERT(!aWorkerScirpt.IsEmpty());
+    mWorkerScript = aWorkerScirpt;
+  }
+
+private:
+  nsCOMPtr<nsIPrincipal> mPrincipal;
+  nsCOMPtr<nsILoadGroup> mLoadGroup;
+  RefPtr<InternalRequest> mRequest;
+  RefPtr<InternalResponse> mResponse;
+  nsCOMPtr<nsIOutputStream> mPipeOutputStream;
+  RefPtr<FetchDriverObserver> mObserver;
+  nsCOMPtr<nsIDocument> mDocument;
+  nsAutoPtr<SRICheckDataVerifier> mSRIDataVerifier;
+  SRIMetadata mSRIMetadata;
+  nsCString mWorkerScript;
+
+#ifdef DEBUG
+  bool mResponseAvailableCalled;
+  bool mFetchCalled;
+#endif
+
+  FetchDriver() = delete;
+  FetchDriver(const FetchDriver&) = delete;
+  FetchDriver& operator=(const FetchDriver&) = delete;
+  ~FetchDriver();
+
+  nsresult HttpFetch();
+  // Returns the filtered response sent to the observer.
+  already_AddRefed<InternalResponse>
+  BeginAndGetFilteredResponse(InternalResponse* aResponse,
+                              bool aFoundOpaqueRedirect);
+  // Utility since not all cases need to do any post processing of the filtered
+  // response.
+  void FailWithNetworkError();
+
+  void SetRequestHeaders(nsIHttpChannel* aChannel) const;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_FetchDriver_h
diff --git a/dom/fetch/FetchIPCTypes.h b/dom/fetch/FetchIPCTypes.h
new file mode 100644
index 0000000000..faedceff27
--- /dev/null
+++ b/dom/fetch/FetchIPCTypes.h
@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_fetch_IPCUtils_h
+#define mozilla_dom_fetch_IPCUtils_h
+
+#include "ipc/IPCMessageUtils.h"
+
+// Fix X11 header brain damage that conflicts with HeadersGuardEnum::None
+#undef None
+
+#include "mozilla/dom/HeadersBinding.h"
+#include "mozilla/dom/RequestBinding.h"
+#include "mozilla/dom/ResponseBinding.h"
+
+namespace IPC {
+  template<>
+  struct ParamTraits<mozilla::dom::HeadersGuardEnum> :
+    public ContiguousEnumSerializer<mozilla::dom::HeadersGuardEnum,
+                                    mozilla::dom::HeadersGuardEnum::None,
+                                    mozilla::dom::HeadersGuardEnum::EndGuard_> {};
+  template<>
+  struct ParamTraits<mozilla::dom::ReferrerPolicy> :
+    public ContiguousEnumSerializer<mozilla::dom::ReferrerPolicy,
+                                    mozilla::dom::ReferrerPolicy::_empty,
+                                    mozilla::dom::ReferrerPolicy::EndGuard_> {};
+  template<>
+  struct ParamTraits<mozilla::dom::RequestMode> :
+    public ContiguousEnumSerializer<mozilla::dom::RequestMode,
+                                    mozilla::dom::RequestMode::Same_origin,
+                                    mozilla::dom::RequestMode::EndGuard_> {};
+  template<>
+  struct ParamTraits<mozilla::dom::RequestCredentials> :
+    public ContiguousEnumSerializer<mozilla::dom::RequestCredentials,
+                                    mozilla::dom::RequestCredentials::Omit,
+                                    mozilla::dom::RequestCredentials::EndGuard_> {};
+  template<>
+  struct ParamTraits<mozilla::dom::RequestCache> :
+    public ContiguousEnumSerializer<mozilla::dom::RequestCache,
+                                    mozilla::dom::RequestCache::Default,
+                                    mozilla::dom::RequestCache::EndGuard_> {};
+  template<>
+  struct ParamTraits<mozilla::dom::RequestRedirect> :
+    public ContiguousEnumSerializer<mozilla::dom::RequestRedirect,
+                                    mozilla::dom::RequestRedirect::Follow,
+                                    mozilla::dom::RequestRedirect::EndGuard_> {};
+  template<>
+  struct ParamTraits<mozilla::dom::ResponseType> :
+    public ContiguousEnumSerializer<mozilla::dom::ResponseType,
+                                    mozilla::dom::ResponseType::Basic,
+                                    mozilla::dom::ResponseType::EndGuard_> {};
+} // namespace IPC
+
+#endif // mozilla_dom_fetch_IPCUtils_h
diff --git a/dom/fetch/FetchTypes.ipdlh b/dom/fetch/FetchTypes.ipdlh
new file mode 100644
index 0000000000..8944252fd7
--- /dev/null
+++ b/dom/fetch/FetchTypes.ipdlh
@@ -0,0 +1,61 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include IPCStream;
+include ChannelInfo;
+include PBackgroundSharedTypes;
+
+using HeadersGuardEnum from "mozilla/dom/FetchIPCTypes.h";
+using ReferrerPolicy from "mozilla/dom/FetchIPCTypes.h";
+using RequestCredentials from "mozilla/dom/FetchIPCTypes.h";
+using RequestMode from "mozilla/dom/FetchIPCTypes.h";
+using ResponseType from "mozilla/dom/FetchIPCTypes.h";
+using RequestRedirect from "mozilla/dom/FetchIPCTypes.h";
+using RequestCache from "mozilla/dom/FetchIPCTypes.h";
+
+namespace mozilla {
+namespace dom {
+
+struct HeadersEntry
+{
+  nsCString name;
+  nsCString value;
+};
+
+// Note, this does not yet serialize *all* of InternalRequest
+// Make sure that it contains the fields that you care about
+struct IPCInternalRequest
+{
+  nsCString[] urls;
+  nsCString method;
+  HeadersEntry[] headers;
+  HeadersGuardEnum headersGuard;
+  nsString referrer;
+  ReferrerPolicy referrerPolicy;
+  RequestMode mode;
+  RequestCredentials credentials;
+  uint32_t contentPolicyType;
+  RequestCache requestCache;
+  RequestRedirect requestRedirect;
+};
+
+// Note, this does not yet serialize *all* of InternalResponse
+// Make sure that it contains the fields that you care about
+struct IPCInternalResponse
+{
+  ResponseType type;
+  nsCString[] urlList;
+  uint32_t status;
+  nsCString statusText;
+  HeadersEntry[] headers;
+  HeadersGuardEnum headersGuard;
+  IPCChannelInfo channelInfo;
+  OptionalPrincipalInfo principalInfo;
+  OptionalIPCStream body;
+  int64_t bodySize;
+};
+
+
+} // namespace ipc
+} // namespace mozilla
diff --git a/dom/fetch/FetchUtil.cpp b/dom/fetch/FetchUtil.cpp
new file mode 100644
index 0000000000..601d99216e
--- /dev/null
+++ b/dom/fetch/FetchUtil.cpp
@@ -0,0 +1,114 @@
+#include "FetchUtil.h"
+
+#include "nsError.h"
+#include "nsIUnicodeDecoder.h"
+#include "nsString.h"
+
+#include "mozilla/dom/EncodingUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+// static
+nsresult
+FetchUtil::GetValidRequestMethod(const nsACString& aMethod, nsCString& outMethod)
+{
+  nsAutoCString upperCaseMethod(aMethod);
+  ToUpperCase(upperCaseMethod);
+  if (!NS_IsValidHTTPToken(aMethod)) {
+    outMethod.SetIsVoid(true);
+    return NS_ERROR_DOM_SYNTAX_ERR;
+  }
+
+  if (upperCaseMethod.EqualsLiteral("CONNECT") ||
+      upperCaseMethod.EqualsLiteral("TRACE") ||
+      upperCaseMethod.EqualsLiteral("TRACK")) {
+    outMethod.SetIsVoid(true);
+    return NS_ERROR_DOM_SECURITY_ERR;
+  }
+
+  if (upperCaseMethod.EqualsLiteral("DELETE") ||
+      upperCaseMethod.EqualsLiteral("GET") ||
+      upperCaseMethod.EqualsLiteral("HEAD") ||
+      upperCaseMethod.EqualsLiteral("OPTIONS") ||
+      upperCaseMethod.EqualsLiteral("POST") ||
+      upperCaseMethod.EqualsLiteral("PUT")) {
+    outMethod = upperCaseMethod;
+  }
+  else {
+    outMethod = aMethod; // Case unchanged for non-standard methods
+  }
+  return NS_OK;
+}
+
+static bool
+FindCRLF(nsACString::const_iterator& aStart,
+         nsACString::const_iterator& aEnd)
+{
+  nsACString::const_iterator end(aEnd);
+  return FindInReadable(NS_LITERAL_CSTRING("\r\n"), aStart, end);
+}
+
+// Reads over a CRLF and positions start after it.
+static bool
+PushOverLine(nsACString::const_iterator& aStart,
+	     const nsACString::const_iterator& aEnd)
+{
+  if (*aStart == nsCRT::CR && (aEnd - aStart > 1) && *(++aStart) == nsCRT::LF) {
+    ++aStart; // advance to after CRLF
+    return true;
+  }
+
+  return false;
+}
+
+// static
+bool
+FetchUtil::ExtractHeader(nsACString::const_iterator& aStart,
+                         nsACString::const_iterator& aEnd,
+                         nsCString& aHeaderName,
+                         nsCString& aHeaderValue,
+                         bool* aWasEmptyHeader)
+{
+  MOZ_ASSERT(aWasEmptyHeader);
+  // Set it to a valid value here so we don't forget later.
+  *aWasEmptyHeader = false;
+
+  const char* beginning = aStart.get();
+  nsACString::const_iterator end(aEnd);
+  if (!FindCRLF(aStart, end)) {
+    return false;
+  }
+
+  if (aStart.get() == beginning) {
+    *aWasEmptyHeader = true;
+    return true;
+  }
+
+  nsAutoCString header(beginning, aStart.get() - beginning);
+
+  nsACString::const_iterator headerStart, iter, headerEnd;
+  header.BeginReading(headerStart);
+  header.EndReading(headerEnd);
+  iter = headerStart;
+  if (!FindCharInReadable(':', iter, headerEnd)) {
+    return false;
+  }
+
+  aHeaderName.Assign(StringHead(header, iter - headerStart));
+  aHeaderName.CompressWhitespace();
+  if (!NS_IsValidHTTPToken(aHeaderName)) {
+    return false;
+  }
+
+  aHeaderValue.Assign(Substring(++iter, headerEnd));
+  if (!NS_IsReasonableHTTPHeaderValue(aHeaderValue)) {
+    return false;
+  }
+  aHeaderValue.CompressWhitespace();
+
+  return PushOverLine(aStart, aEnd);
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/FetchUtil.h b/dom/fetch/FetchUtil.h
new file mode 100644
index 0000000000..d99aa39b44
--- /dev/null
+++ b/dom/fetch/FetchUtil.h
@@ -0,0 +1,42 @@
+#ifndef mozilla_dom_FetchUtil_h
+#define mozilla_dom_FetchUtil_h
+
+#include "nsString.h"
+#include "nsError.h"
+
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/File.h"
+#include "mozilla/dom/FormData.h"
+
+namespace mozilla {
+namespace dom {
+
+class FetchUtil final
+{
+private:
+  FetchUtil() = delete;
+
+public:
+  /**
+  * Sets outMethod to a valid HTTP request method string based on an input method.
+  * Implements checks and normalization as specified by the Fetch specification.
+  * Returns NS_ERROR_DOM_SECURITY_ERR if the method is invalid.
+  * Otherwise returns NS_OK and the normalized method via outMethod.
+  */
+  static nsresult
+  GetValidRequestMethod(const nsACString& aMethod, nsCString& outMethod);
+
+  /**
+   * Extracts an HTTP header from a substring range.
+   */
+  static bool
+  ExtractHeader(nsACString::const_iterator& aStart,
+                nsACString::const_iterator& aEnd,
+                nsCString& aHeaderName,
+                nsCString& aHeaderValue,
+                bool* aWasEmptyHeader);
+};
+
+} // namespace dom
+} // namespace mozilla
+#endif
diff --git a/dom/fetch/Headers.cpp b/dom/fetch/Headers.cpp
new file mode 100644
index 0000000000..1e1a46c62c
--- /dev/null
+++ b/dom/fetch/Headers.cpp
@@ -0,0 +1,97 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/Headers.h"
+
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/WorkerPrivate.h"
+#include "mozilla/Preferences.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(Headers)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(Headers)
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(Headers, mOwner)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(Headers)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+// static
+already_AddRefed<Headers>
+Headers::Constructor(const GlobalObject& aGlobal,
+                     const Optional<HeadersOrByteStringSequenceSequenceOrByteStringMozMap>& aInit,
+                     ErrorResult& aRv)
+{
+  RefPtr<InternalHeaders> ih = new InternalHeaders();
+  RefPtr<Headers> headers = new Headers(aGlobal.GetAsSupports(), ih);
+
+  if (!aInit.WasPassed()) {
+    return headers.forget();
+  }
+
+  if (aInit.Value().IsHeaders()) {
+    ih->Fill(*aInit.Value().GetAsHeaders().mInternalHeaders, aRv);
+  } else if (aInit.Value().IsByteStringSequenceSequence()) {
+    ih->Fill(aInit.Value().GetAsByteStringSequenceSequence(), aRv);
+  } else if (aInit.Value().IsByteStringMozMap()) {
+    ih->Fill(aInit.Value().GetAsByteStringMozMap(), aRv);
+  }
+
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  return headers.forget();
+}
+
+// static
+already_AddRefed<Headers>
+Headers::Constructor(const GlobalObject& aGlobal,
+                     const OwningHeadersOrByteStringSequenceSequenceOrByteStringMozMap& aInit,
+                     ErrorResult& aRv)
+{
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+  return Create(global, aInit, aRv);
+}
+
+/* static */ already_AddRefed<Headers>
+Headers::Create(nsIGlobalObject* aGlobal,
+                const OwningHeadersOrByteStringSequenceSequenceOrByteStringMozMap& aInit,
+                ErrorResult& aRv)
+{
+  RefPtr<InternalHeaders> ih = new InternalHeaders();
+  RefPtr<Headers> headers = new Headers(aGlobal, ih);
+
+  if (aInit.IsHeaders()) {
+    ih->Fill(*(aInit.GetAsHeaders().get()->mInternalHeaders), aRv);
+  } else if (aInit.IsByteStringSequenceSequence()) {
+    ih->Fill(aInit.GetAsByteStringSequenceSequence(), aRv);
+  } else if (aInit.IsByteStringMozMap()) {
+    ih->Fill(aInit.GetAsByteStringMozMap(), aRv);
+  }
+
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  return headers.forget();
+}
+
+JSObject*
+Headers::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return mozilla::dom::HeadersBinding::Wrap(aCx, this, aGivenProto);
+}
+
+Headers::~Headers()
+{
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/Headers.h b/dom/fetch/Headers.h
new file mode 100644
index 0000000000..b603dc836c
--- /dev/null
+++ b/dom/fetch/Headers.h
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_Headers_h
+#define mozilla_dom_Headers_h
+
+#include "mozilla/dom/HeadersBinding.h"
+
+#include "nsClassHashtable.h"
+#include "nsWrapperCache.h"
+
+#include "InternalHeaders.h"
+
+namespace mozilla {
+
+class ErrorResult;
+
+namespace dom {
+
+template<typename T> class MozMap;
+class HeadersOrByteStringSequenceSequenceOrByteStringMozMap;
+class OwningHeadersOrByteStringSequenceSequenceOrByteStringMozMap;
+
+/**
+ * This Headers class is only used to represent the content facing Headers
+ * object. It is actually backed by an InternalHeaders implementation. Gecko
+ * code should NEVER use this, except in the Request and Response
+ * implementations, where they must always be created from the backing
+ * InternalHeaders object.
+ */
+class Headers final : public nsISupports
+                    , public nsWrapperCache
+{
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(Headers)
+
+  friend class Request;
+  friend class Response;
+
+private:
+  nsCOMPtr<nsISupports> mOwner;
+  RefPtr<InternalHeaders> mInternalHeaders;
+
+public:
+  explicit Headers(nsISupports* aOwner, InternalHeaders* aInternalHeaders)
+    : mOwner(aOwner)
+    , mInternalHeaders(aInternalHeaders)
+  {
+  }
+
+  explicit Headers(const Headers& aOther) = delete;
+
+  static bool PrefEnabled(JSContext* cx, JSObject* obj);
+
+  static already_AddRefed<Headers>
+  Constructor(const GlobalObject& aGlobal,
+              const Optional<HeadersOrByteStringSequenceSequenceOrByteStringMozMap>& aInit,
+              ErrorResult& aRv);
+
+  static already_AddRefed<Headers>
+  Constructor(const GlobalObject& aGlobal,
+              const OwningHeadersOrByteStringSequenceSequenceOrByteStringMozMap& aInit,
+              ErrorResult& aRv);
+
+  static already_AddRefed<Headers>
+  Create(nsIGlobalObject* aGlobalObject,
+         const OwningHeadersOrByteStringSequenceSequenceOrByteStringMozMap& aInit,
+         ErrorResult& aRv);
+
+  void Append(const nsACString& aName, const nsACString& aValue,
+              ErrorResult& aRv)
+  {
+    mInternalHeaders->Append(aName, aValue, aRv);
+  }
+
+  void Delete(const nsACString& aName, ErrorResult& aRv)
+  {
+    mInternalHeaders->Delete(aName, aRv);
+  }
+
+  void Get(const nsACString& aName, nsACString& aValue, ErrorResult& aRv) const
+  {
+    mInternalHeaders->Get(aName, aValue, aRv);
+  }
+
+  void GetFirst(const nsACString& aName, nsACString& aValue, ErrorResult& aRv) const
+  {
+    mInternalHeaders->GetFirst(aName, aValue, aRv);
+  }
+
+  bool Has(const nsACString& aName, ErrorResult& aRv) const
+  {
+    return mInternalHeaders->Has(aName, aRv);
+  }
+
+  void Set(const nsACString& aName, const nsACString& aValue, ErrorResult& aRv)
+  {
+    mInternalHeaders->Set(aName, aValue, aRv);
+  }
+
+  uint32_t GetIterableLength() const
+  {
+    return mInternalHeaders->GetIterableLength();
+  }
+  const nsString GetKeyAtIndex(unsigned aIndex) const
+  {
+    return mInternalHeaders->GetKeyAtIndex(aIndex);
+  }
+  const nsString GetValueAtIndex(unsigned aIndex) const
+  {
+    return mInternalHeaders->GetValueAtIndex(aIndex);
+  }
+
+  // ChromeOnly
+  HeadersGuardEnum Guard() const
+  {
+    return mInternalHeaders->Guard();
+  }
+
+  void SetGuard(HeadersGuardEnum aGuard, ErrorResult& aRv)
+  {
+    mInternalHeaders->SetGuard(aGuard, aRv);
+  }
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+  nsISupports* GetParentObject() const { return mOwner; }
+
+private:
+  virtual ~Headers();
+
+  InternalHeaders*
+  GetInternalHeaders() const
+  {
+    return mInternalHeaders;
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_Headers_h
diff --git a/dom/fetch/InternalHeaders.cpp b/dom/fetch/InternalHeaders.cpp
new file mode 100644
index 0000000000..e81863173b
--- /dev/null
+++ b/dom/fetch/InternalHeaders.cpp
@@ -0,0 +1,423 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/InternalHeaders.h"
+
+#include "mozilla/dom/FetchTypes.h"
+#include "mozilla/ErrorResult.h"
+
+#include "nsCharSeparatedTokenizer.h"
+#include "nsContentUtils.h"
+#include "nsNetUtil.h"
+#include "nsReadableUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+InternalHeaders::InternalHeaders(const nsTArray<Entry>&& aHeaders,
+                                 HeadersGuardEnum aGuard)
+  : mGuard(aGuard)
+  , mList(aHeaders)
+{
+}
+
+InternalHeaders::InternalHeaders(const nsTArray<HeadersEntry>& aHeadersEntryList,
+                                 HeadersGuardEnum aGuard)
+  : mGuard(aGuard)
+{
+  for (const HeadersEntry& headersEntry : aHeadersEntryList) {
+    mList.AppendElement(Entry(headersEntry.name(), headersEntry.value()));
+  }
+}
+
+void
+InternalHeaders::ToIPC(nsTArray<HeadersEntry>& aIPCHeaders,
+                       HeadersGuardEnum& aGuard)
+{
+  aGuard = mGuard;
+
+  aIPCHeaders.Clear();
+  for (Entry& entry : mList) {
+    aIPCHeaders.AppendElement(HeadersEntry(entry.mName, entry.mValue));
+  }
+}
+
+void
+InternalHeaders::Append(const nsACString& aName, const nsACString& aValue,
+                        ErrorResult& aRv)
+{
+  nsAutoCString lowerName;
+  ToLowerCase(aName, lowerName);
+
+  if (IsInvalidMutableHeader(lowerName, aValue, aRv)) {
+    return;
+  }
+
+  mList.AppendElement(Entry(lowerName, aValue));
+}
+
+void
+InternalHeaders::Delete(const nsACString& aName, ErrorResult& aRv)
+{
+  nsAutoCString lowerName;
+  ToLowerCase(aName, lowerName);
+
+  if (IsInvalidMutableHeader(lowerName, aRv)) {
+    return;
+  }
+
+  // remove in reverse order to minimize copying
+  for (int32_t i = mList.Length() - 1; i >= 0; --i) {
+    if (lowerName == mList[i].mName) {
+      mList.RemoveElementAt(i);
+    }
+  }
+}
+
+void
+InternalHeaders::Get(const nsACString& aName, nsACString& aValue, ErrorResult& aRv) const
+{
+  nsAutoCString lowerName;
+  ToLowerCase(aName, lowerName);
+
+  if (IsInvalidName(lowerName, aRv)) {
+    return;
+  }
+
+  const char* delimiter = ",";
+  bool firstValueFound = false;
+
+  for (uint32_t i = 0; i < mList.Length(); ++i) {
+    if (lowerName == mList[i].mName) {
+      if (firstValueFound) {
+        aValue += delimiter;
+      }
+      aValue += mList[i].mValue;
+      firstValueFound = true;
+    }
+  }
+
+  // No value found, so return null to content
+  if (!firstValueFound) {
+    aValue.SetIsVoid(true);
+  }
+}
+
+void
+InternalHeaders::GetFirst(const nsACString& aName, nsACString& aValue, ErrorResult& aRv) const
+{
+  nsAutoCString lowerName;
+  ToLowerCase(aName, lowerName);
+
+  if (IsInvalidName(lowerName, aRv)) {
+    return;
+  }
+
+  for (uint32_t i = 0; i < mList.Length(); ++i) {
+    if (lowerName == mList[i].mName) {
+      aValue = mList[i].mValue;
+      return;
+    }
+  }
+
+  // No value found, so return null to content
+  aValue.SetIsVoid(true);
+}
+
+bool
+InternalHeaders::Has(const nsACString& aName, ErrorResult& aRv) const
+{
+  nsAutoCString lowerName;
+  ToLowerCase(aName, lowerName);
+
+  if (IsInvalidName(lowerName, aRv)) {
+    return false;
+  }
+
+  for (uint32_t i = 0; i < mList.Length(); ++i) {
+    if (lowerName == mList[i].mName) {
+      return true;
+    }
+  }
+  return false;
+}
+
+void
+InternalHeaders::Set(const nsACString& aName, const nsACString& aValue, ErrorResult& aRv)
+{
+  nsAutoCString lowerName;
+  ToLowerCase(aName, lowerName);
+
+  if (IsInvalidMutableHeader(lowerName, aValue, aRv)) {
+    return;
+  }
+
+  int32_t firstIndex = INT32_MAX;
+
+  // remove in reverse order to minimize copying
+  for (int32_t i = mList.Length() - 1; i >= 0; --i) {
+    if (lowerName == mList[i].mName) {
+      firstIndex = std::min(firstIndex, i);
+      mList.RemoveElementAt(i);
+    }
+  }
+
+  if (firstIndex < INT32_MAX) {
+    Entry* entry = mList.InsertElementAt(firstIndex);
+    entry->mName = lowerName;
+    entry->mValue = aValue;
+  } else {
+    mList.AppendElement(Entry(lowerName, aValue));
+  }
+}
+
+void
+InternalHeaders::Clear()
+{
+  mList.Clear();
+}
+
+void
+InternalHeaders::SetGuard(HeadersGuardEnum aGuard, ErrorResult& aRv)
+{
+  // The guard is only checked during ::Set() and ::Append() in the spec.  It
+  // does not require revalidating headers already set.
+  mGuard = aGuard;
+}
+
+InternalHeaders::~InternalHeaders()
+{
+}
+
+// static
+bool
+InternalHeaders::IsSimpleHeader(const nsACString& aName, const nsACString& aValue)
+{
+  // Note, we must allow a null content-type value here to support
+  // get("content-type"), but the IsInvalidValue() check will prevent null
+  // from being set or appended.
+  return aName.EqualsLiteral("accept") ||
+         aName.EqualsLiteral("accept-language") ||
+         aName.EqualsLiteral("content-language") ||
+         (aName.EqualsLiteral("content-type") &&
+          nsContentUtils::IsAllowedNonCorsContentType(aValue));
+}
+
+// static
+bool
+InternalHeaders::IsRevalidationHeader(const nsACString& aName)
+{
+  return aName.EqualsLiteral("if-modified-since") ||
+         aName.EqualsLiteral("if-none-match") ||
+         aName.EqualsLiteral("if-unmodified-since") ||
+         aName.EqualsLiteral("if-match") ||
+         aName.EqualsLiteral("if-range");
+}
+
+//static
+bool
+InternalHeaders::IsInvalidName(const nsACString& aName, ErrorResult& aRv)
+{
+  if (!NS_IsValidHTTPToken(aName)) {
+    NS_ConvertUTF8toUTF16 label(aName);
+    aRv.ThrowTypeError<MSG_INVALID_HEADER_NAME>(label);
+    return true;
+  }
+
+  return false;
+}
+
+// static
+bool
+InternalHeaders::IsInvalidValue(const nsACString& aValue, ErrorResult& aRv)
+{
+  if (!NS_IsReasonableHTTPHeaderValue(aValue)) {
+    NS_ConvertUTF8toUTF16 label(aValue);
+    aRv.ThrowTypeError<MSG_INVALID_HEADER_VALUE>(label);
+    return true;
+  }
+  return false;
+}
+
+bool
+InternalHeaders::IsImmutable(ErrorResult& aRv) const
+{
+  if (mGuard == HeadersGuardEnum::Immutable) {
+    aRv.ThrowTypeError<MSG_HEADERS_IMMUTABLE>();
+    return true;
+  }
+  return false;
+}
+
+bool
+InternalHeaders::IsForbiddenRequestHeader(const nsACString& aName) const
+{
+  return mGuard == HeadersGuardEnum::Request &&
+         nsContentUtils::IsForbiddenRequestHeader(aName);
+}
+
+bool
+InternalHeaders::IsForbiddenRequestNoCorsHeader(const nsACString& aName) const
+{
+  return mGuard == HeadersGuardEnum::Request_no_cors &&
+         !IsSimpleHeader(aName, EmptyCString());
+}
+
+bool
+InternalHeaders::IsForbiddenRequestNoCorsHeader(const nsACString& aName,
+                                                const nsACString& aValue) const
+{
+  return mGuard == HeadersGuardEnum::Request_no_cors &&
+         !IsSimpleHeader(aName, aValue);
+}
+
+bool
+InternalHeaders::IsForbiddenResponseHeader(const nsACString& aName) const
+{
+  return mGuard == HeadersGuardEnum::Response &&
+         nsContentUtils::IsForbiddenResponseHeader(aName);
+}
+
+void
+InternalHeaders::Fill(const InternalHeaders& aInit, ErrorResult& aRv)
+{
+  const nsTArray<Entry>& list = aInit.mList;
+  for (uint32_t i = 0; i < list.Length() && !aRv.Failed(); ++i) {
+    const Entry& entry = list[i];
+    Append(entry.mName, entry.mValue, aRv);
+  }
+}
+
+void
+InternalHeaders::Fill(const Sequence<Sequence<nsCString>>& aInit, ErrorResult& aRv)
+{
+  for (uint32_t i = 0; i < aInit.Length() && !aRv.Failed(); ++i) {
+    const Sequence<nsCString>& tuple = aInit[i];
+    if (tuple.Length() != 2) {
+      aRv.ThrowTypeError<MSG_INVALID_HEADER_SEQUENCE>();
+      return;
+    }
+    Append(tuple[0], tuple[1], aRv);
+  }
+}
+
+void
+InternalHeaders::Fill(const MozMap<nsCString>& aInit, ErrorResult& aRv)
+{
+  nsTArray<nsString> keys;
+  aInit.GetKeys(keys);
+  for (uint32_t i = 0; i < keys.Length() && !aRv.Failed(); ++i) {
+    Append(NS_ConvertUTF16toUTF8(keys[i]), aInit.Get(keys[i]), aRv);
+  }
+}
+
+bool
+InternalHeaders::HasOnlySimpleHeaders() const
+{
+  for (uint32_t i = 0; i < mList.Length(); ++i) {
+    if (!IsSimpleHeader(mList[i].mName, mList[i].mValue)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool
+InternalHeaders::HasRevalidationHeaders() const
+{
+  for (uint32_t i = 0; i < mList.Length(); ++i) {
+    if (IsRevalidationHeader(mList[i].mName)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+// static
+already_AddRefed<InternalHeaders>
+InternalHeaders::BasicHeaders(InternalHeaders* aHeaders)
+{
+  RefPtr<InternalHeaders> basic = new InternalHeaders(*aHeaders);
+  ErrorResult result;
+  // The Set-Cookie headers cannot be invalid mutable headers, so the Delete
+  // must succeed.
+  basic->Delete(NS_LITERAL_CSTRING("Set-Cookie"), result);
+  MOZ_ASSERT(!result.Failed());
+  basic->Delete(NS_LITERAL_CSTRING("Set-Cookie2"), result);
+  MOZ_ASSERT(!result.Failed());
+  return basic.forget();
+}
+
+// static
+already_AddRefed<InternalHeaders>
+InternalHeaders::CORSHeaders(InternalHeaders* aHeaders)
+{
+  RefPtr<InternalHeaders> cors = new InternalHeaders(aHeaders->mGuard);
+  ErrorResult result;
+
+  nsAutoCString acExposedNames;
+  aHeaders->GetFirst(NS_LITERAL_CSTRING("Access-Control-Expose-Headers"), acExposedNames, result);
+  MOZ_ASSERT(!result.Failed());
+
+  AutoTArray<nsCString, 5> exposeNamesArray;
+  nsCCharSeparatedTokenizer exposeTokens(acExposedNames, ',');
+  while (exposeTokens.hasMoreTokens()) {
+    const nsDependentCSubstring& token = exposeTokens.nextToken();
+    if (token.IsEmpty()) {
+      continue;
+    }
+
+    if (!NS_IsValidHTTPToken(token)) {
+      NS_WARNING("Got invalid HTTP token in Access-Control-Expose-Headers. Header value is:");
+      NS_WARNING(acExposedNames.get());
+      exposeNamesArray.Clear();
+      break;
+    }
+
+    exposeNamesArray.AppendElement(token);
+  }
+
+  nsCaseInsensitiveCStringArrayComparator comp;
+  for (uint32_t i = 0; i < aHeaders->mList.Length(); ++i) {
+    const Entry& entry = aHeaders->mList[i];
+    if (entry.mName.EqualsASCII("cache-control") ||
+        entry.mName.EqualsASCII("content-language") ||
+        entry.mName.EqualsASCII("content-type") ||
+        entry.mName.EqualsASCII("expires") ||
+        entry.mName.EqualsASCII("last-modified") ||
+        entry.mName.EqualsASCII("pragma") ||
+        exposeNamesArray.Contains(entry.mName, comp)) {
+      cors->Append(entry.mName, entry.mValue, result);
+      MOZ_ASSERT(!result.Failed());
+    }
+  }
+
+  return cors.forget();
+}
+
+void
+InternalHeaders::GetEntries(nsTArray<InternalHeaders::Entry>& aEntries) const
+{
+  MOZ_ASSERT(aEntries.IsEmpty());
+  aEntries.AppendElements(mList);
+}
+
+void
+InternalHeaders::GetUnsafeHeaders(nsTArray<nsCString>& aNames) const
+{
+  MOZ_ASSERT(aNames.IsEmpty());
+  for (uint32_t i = 0; i < mList.Length(); ++i) {
+    const Entry& header = mList[i];
+    if (!InternalHeaders::IsSimpleHeader(header.mName, header.mValue)) {
+      aNames.AppendElement(header.mName);
+    }
+  }
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/InternalHeaders.h b/dom/fetch/InternalHeaders.h
new file mode 100644
index 0000000000..e470666694
--- /dev/null
+++ b/dom/fetch/InternalHeaders.h
@@ -0,0 +1,160 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_InternalHeaders_h
+#define mozilla_dom_InternalHeaders_h
+
+// needed for HeadersGuardEnum.
+#include "mozilla/dom/HeadersBinding.h"
+#include "mozilla/dom/UnionTypes.h"
+
+#include "nsClassHashtable.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+
+class ErrorResult;
+
+namespace dom {
+
+template<typename T> class MozMap;
+class HeadersEntry;
+
+class InternalHeaders final
+{
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(InternalHeaders)
+
+public:
+  struct Entry
+  {
+    Entry(const nsACString& aName, const nsACString& aValue)
+      : mName(aName)
+      , mValue(aValue)
+    { }
+
+    Entry() { }
+
+    nsCString mName;
+    nsCString mValue;
+  };
+
+private:
+  HeadersGuardEnum mGuard;
+  nsTArray<Entry> mList;
+
+public:
+  explicit InternalHeaders(HeadersGuardEnum aGuard = HeadersGuardEnum::None)
+    : mGuard(aGuard)
+  {
+  }
+
+  explicit InternalHeaders(const InternalHeaders& aOther)
+    : mGuard(HeadersGuardEnum::None)
+  {
+    ErrorResult result;
+    Fill(aOther, result);
+    MOZ_ASSERT(!result.Failed());
+    // Note that it's important to set the guard after Fill(), to make sure
+    // that Fill() doesn't fail if aOther is immutable.
+    mGuard = aOther.mGuard;
+  }
+
+  explicit InternalHeaders(const nsTArray<Entry>&& aHeaders,
+                           HeadersGuardEnum aGuard = HeadersGuardEnum::None);
+
+  InternalHeaders(const nsTArray<HeadersEntry>& aHeadersEntryList,
+                  HeadersGuardEnum aGuard);
+
+  void ToIPC(nsTArray<HeadersEntry>& aIPCHeaders,
+             HeadersGuardEnum& aGuard);
+
+  void Append(const nsACString& aName, const nsACString& aValue,
+              ErrorResult& aRv);
+  void Delete(const nsACString& aName, ErrorResult& aRv);
+  void Get(const nsACString& aName, nsACString& aValue, ErrorResult& aRv) const;
+  void GetFirst(const nsACString& aName, nsACString& aValue, ErrorResult& aRv) const;
+  bool Has(const nsACString& aName, ErrorResult& aRv) const;
+  void Set(const nsACString& aName, const nsACString& aValue, ErrorResult& aRv);
+
+  uint32_t GetIterableLength() const
+  {
+    return mList.Length();
+  }
+  const NS_ConvertASCIItoUTF16 GetKeyAtIndex(unsigned aIndex) const
+  {
+    MOZ_ASSERT(aIndex < mList.Length());
+    return NS_ConvertASCIItoUTF16(mList[aIndex].mName);
+  }
+  const NS_ConvertASCIItoUTF16 GetValueAtIndex(unsigned aIndex) const
+  {
+    MOZ_ASSERT(aIndex < mList.Length());
+    return NS_ConvertASCIItoUTF16(mList[aIndex].mValue);
+  }
+
+  void Clear();
+
+  HeadersGuardEnum Guard() const { return mGuard; }
+  void SetGuard(HeadersGuardEnum aGuard, ErrorResult& aRv);
+
+  void Fill(const InternalHeaders& aInit, ErrorResult& aRv);
+  void Fill(const Sequence<Sequence<nsCString>>& aInit, ErrorResult& aRv);
+  void Fill(const MozMap<nsCString>& aInit, ErrorResult& aRv);
+
+  bool HasOnlySimpleHeaders() const;
+
+  bool HasRevalidationHeaders() const;
+
+  static already_AddRefed<InternalHeaders>
+  BasicHeaders(InternalHeaders* aHeaders);
+
+  static already_AddRefed<InternalHeaders>
+  CORSHeaders(InternalHeaders* aHeaders);
+
+  void
+  GetEntries(nsTArray<InternalHeaders::Entry>& aEntries) const;
+
+  void
+  GetUnsafeHeaders(nsTArray<nsCString>& aNames) const;
+private:
+  virtual ~InternalHeaders();
+
+  static bool IsInvalidName(const nsACString& aName, ErrorResult& aRv);
+  static bool IsInvalidValue(const nsACString& aValue, ErrorResult& aRv);
+  bool IsImmutable(ErrorResult& aRv) const;
+  bool IsForbiddenRequestHeader(const nsACString& aName) const;
+  bool IsForbiddenRequestNoCorsHeader(const nsACString& aName) const;
+  bool IsForbiddenRequestNoCorsHeader(const nsACString& aName,
+                                      const nsACString& aValue) const;
+  bool IsForbiddenResponseHeader(const nsACString& aName) const;
+
+  bool IsInvalidMutableHeader(const nsACString& aName,
+                              ErrorResult& aRv) const
+  {
+    return IsInvalidMutableHeader(aName, EmptyCString(), aRv);
+  }
+
+  bool IsInvalidMutableHeader(const nsACString& aName,
+                              const nsACString& aValue,
+                              ErrorResult& aRv) const
+  {
+    return IsInvalidName(aName, aRv) ||
+           IsInvalidValue(aValue, aRv) ||
+           IsImmutable(aRv) ||
+           IsForbiddenRequestHeader(aName) ||
+           IsForbiddenRequestNoCorsHeader(aName, aValue) ||
+           IsForbiddenResponseHeader(aName);
+  }
+
+  static bool IsSimpleHeader(const nsACString& aName,
+                             const nsACString& aValue);
+
+  static bool IsRevalidationHeader(const nsACString& aName);
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_InternalHeaders_h
diff --git a/dom/fetch/InternalRequest.cpp b/dom/fetch/InternalRequest.cpp
new file mode 100644
index 0000000000..85feabde3d
--- /dev/null
+++ b/dom/fetch/InternalRequest.cpp
@@ -0,0 +1,495 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "InternalRequest.h"
+
+#include "nsIContentPolicy.h"
+#include "nsIDocument.h"
+#include "nsStreamUtils.h"
+
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/FetchTypes.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/workers/Workers.h"
+
+#include "WorkerPrivate.h"
+
+namespace mozilla {
+namespace dom {
+// The global is used to extract the principal.
+already_AddRefed<InternalRequest>
+InternalRequest::GetRequestConstructorCopy(nsIGlobalObject* aGlobal, ErrorResult& aRv) const
+{
+  MOZ_RELEASE_ASSERT(!mURLList.IsEmpty(), "Internal Request's urlList should not be empty when copied from constructor.");
+  RefPtr<InternalRequest> copy = new InternalRequest(mURLList.LastElement(),
+                                                     mFragment);
+  copy->SetMethod(mMethod);
+  copy->mHeaders = new InternalHeaders(*mHeaders);
+  copy->SetUnsafeRequest();
+  copy->mBodyStream = mBodyStream;
+  copy->mForceOriginHeader = true;
+  // The "client" is not stored in our implementation. Fetch API users should
+  // use the appropriate window/document/principal and other Gecko security
+  // mechanisms as appropriate.
+  copy->mSameOriginDataURL = true;
+  copy->mPreserveContentCodings = true;
+  copy->mReferrer = mReferrer;
+  copy->mReferrerPolicy = mReferrerPolicy;
+  copy->mEnvironmentReferrerPolicy = mEnvironmentReferrerPolicy;
+  copy->mIntegrity = mIntegrity;
+
+  copy->mContentPolicyType = mContentPolicyTypeOverridden ?
+                             mContentPolicyType :
+                             nsIContentPolicy::TYPE_FETCH;
+  copy->mMode = mMode;
+  copy->mCredentialsMode = mCredentialsMode;
+  copy->mCacheMode = mCacheMode;
+  copy->mRedirectMode = mRedirectMode;
+  copy->mCreatedByFetchEvent = mCreatedByFetchEvent;
+  copy->mContentPolicyTypeOverridden = mContentPolicyTypeOverridden;
+  return copy.forget();
+}
+
+already_AddRefed<InternalRequest>
+InternalRequest::Clone()
+{
+  RefPtr<InternalRequest> clone = new InternalRequest(*this);
+
+  if (!mBodyStream) {
+    return clone.forget();
+  }
+
+  nsCOMPtr<nsIInputStream> clonedBody;
+  nsCOMPtr<nsIInputStream> replacementBody;
+
+  nsresult rv = NS_CloneInputStream(mBodyStream, getter_AddRefs(clonedBody),
+                                    getter_AddRefs(replacementBody));
+  if (NS_WARN_IF(NS_FAILED(rv))) { return nullptr; }
+
+  clone->mBodyStream.swap(clonedBody);
+  if (replacementBody) {
+    mBodyStream.swap(replacementBody);
+  }
+  return clone.forget();
+}
+InternalRequest::InternalRequest(const nsACString& aURL,
+                                 const nsACString& aFragment)
+  : mMethod("GET")
+  , mHeaders(new InternalHeaders(HeadersGuardEnum::None))
+  , mContentPolicyType(nsIContentPolicy::TYPE_FETCH)
+  , mReferrer(NS_LITERAL_STRING(kFETCH_CLIENT_REFERRER_STR))
+  , mReferrerPolicy(ReferrerPolicy::_empty)
+  , mEnvironmentReferrerPolicy(net::RP_Default)
+  , mMode(RequestMode::No_cors)
+  , mCredentialsMode(RequestCredentials::Omit)
+  , mResponseTainting(LoadTainting::Basic)
+  , mCacheMode(RequestCache::Default)
+  , mRedirectMode(RequestRedirect::Follow)
+  , mAuthenticationFlag(false)
+  , mForceOriginHeader(false)
+  , mPreserveContentCodings(false)
+    // FIXME(nsm): This should be false by default, but will lead to the
+    // algorithm never loading data: URLs right now. See Bug 1018872 about
+    // how certain contexts will override it to set it to true. Fetch
+    // specification does not handle this yet.
+  , mSameOriginDataURL(true)
+  , mSkipServiceWorker(false)
+  , mSynchronous(false)
+  , mUnsafeRequest(false)
+  , mUseURLCredentials(false)
+{
+  MOZ_ASSERT(!aURL.IsEmpty());
+  AddURL(aURL, aFragment);
+}
+InternalRequest::InternalRequest(const nsACString& aURL,
+                                 const nsACString& aFragment,
+                                 const nsACString& aMethod,
+                                 already_AddRefed<InternalHeaders> aHeaders,
+                                 RequestCache aCacheMode,
+                                 RequestMode aMode,
+                                 RequestRedirect aRequestRedirect,
+                                 RequestCredentials aRequestCredentials,
+                                 const nsAString& aReferrer,
+                                 ReferrerPolicy aReferrerPolicy,
+                                 nsContentPolicyType aContentPolicyType,
+                                 const nsAString& aIntegrity)
+  : mMethod(aMethod)
+  , mHeaders(aHeaders)
+  , mContentPolicyType(aContentPolicyType)
+  , mReferrer(aReferrer)
+  , mReferrerPolicy(aReferrerPolicy)
+  , mEnvironmentReferrerPolicy(net::RP_Default)
+  , mMode(aMode)
+  , mCredentialsMode(aRequestCredentials)
+  , mResponseTainting(LoadTainting::Basic)
+  , mCacheMode(aCacheMode)
+  , mRedirectMode(aRequestRedirect)
+  , mIntegrity(aIntegrity)
+  , mAuthenticationFlag(false)
+  , mForceOriginHeader(false)
+  , mPreserveContentCodings(false)
+    // FIXME See the above comment in the default constructor.
+  , mSameOriginDataURL(true)
+  , mSkipServiceWorker(false)
+  , mSynchronous(false)
+  , mUnsafeRequest(false)
+  , mUseURLCredentials(false)
+{
+  MOZ_ASSERT(!aURL.IsEmpty());
+  AddURL(aURL, aFragment);
+}
+InternalRequest::InternalRequest(const InternalRequest& aOther)
+  : mMethod(aOther.mMethod)
+  , mURLList(aOther.mURLList)
+  , mHeaders(new InternalHeaders(*aOther.mHeaders))
+  , mContentPolicyType(aOther.mContentPolicyType)
+  , mReferrer(aOther.mReferrer)
+  , mReferrerPolicy(aOther.mReferrerPolicy)
+  , mEnvironmentReferrerPolicy(aOther.mEnvironmentReferrerPolicy)
+  , mMode(aOther.mMode)
+  , mCredentialsMode(aOther.mCredentialsMode)
+  , mResponseTainting(aOther.mResponseTainting)
+  , mCacheMode(aOther.mCacheMode)
+  , mRedirectMode(aOther.mRedirectMode)
+  , mIntegrity(aOther.mIntegrity)
+  , mFragment(aOther.mFragment)
+  , mAuthenticationFlag(aOther.mAuthenticationFlag)
+  , mForceOriginHeader(aOther.mForceOriginHeader)
+  , mPreserveContentCodings(aOther.mPreserveContentCodings)
+  , mSameOriginDataURL(aOther.mSameOriginDataURL)
+  , mSkipServiceWorker(aOther.mSkipServiceWorker)
+  , mSynchronous(aOther.mSynchronous)
+  , mUnsafeRequest(aOther.mUnsafeRequest)
+  , mUseURLCredentials(aOther.mUseURLCredentials)
+  , mCreatedByFetchEvent(aOther.mCreatedByFetchEvent)
+  , mContentPolicyTypeOverridden(aOther.mContentPolicyTypeOverridden)
+{
+  // NOTE: does not copy body stream... use the fallible Clone() for that
+}
+
+InternalRequest::InternalRequest(const IPCInternalRequest& aIPCRequest)
+  : mMethod(aIPCRequest.method())
+  , mURLList(aIPCRequest.urls())
+  , mHeaders(new InternalHeaders(aIPCRequest.headers(),
+                                 aIPCRequest.headersGuard()))
+  , mContentPolicyType(aIPCRequest.contentPolicyType())
+  , mReferrer(aIPCRequest.referrer())
+  , mReferrerPolicy(aIPCRequest.referrerPolicy())
+  , mMode(aIPCRequest.mode())
+  , mCredentialsMode(aIPCRequest.credentials())
+  , mCacheMode(aIPCRequest.requestCache())
+  , mRedirectMode(aIPCRequest.requestRedirect())
+{
+  MOZ_ASSERT(!mURLList.IsEmpty());
+}
+
+InternalRequest::~InternalRequest()
+{
+}
+
+void
+InternalRequest::ToIPC(IPCInternalRequest* aIPCRequest)
+{
+  MOZ_ASSERT(aIPCRequest);
+  MOZ_ASSERT(!mURLList.IsEmpty());
+  aIPCRequest->urls() = mURLList;
+  aIPCRequest->method() = mMethod;
+
+  mHeaders->ToIPC(aIPCRequest->headers(), aIPCRequest->headersGuard());
+
+  aIPCRequest->referrer() = mReferrer;
+  aIPCRequest->referrerPolicy() = mReferrerPolicy;
+  aIPCRequest->mode() = mMode;
+  aIPCRequest->credentials() = mCredentialsMode;
+  aIPCRequest->contentPolicyType() = mContentPolicyType;
+  aIPCRequest->requestCache() = mCacheMode;
+  aIPCRequest->requestRedirect() = mRedirectMode;
+}
+
+void
+InternalRequest::SetContentPolicyType(nsContentPolicyType aContentPolicyType)
+{
+  mContentPolicyType = aContentPolicyType;
+}
+
+void
+InternalRequest::OverrideContentPolicyType(nsContentPolicyType aContentPolicyType)
+{
+  SetContentPolicyType(aContentPolicyType);
+  mContentPolicyTypeOverridden = true;
+}
+
+/* static */
+RequestContext
+InternalRequest::MapContentPolicyTypeToRequestContext(nsContentPolicyType aContentPolicyType)
+{
+  RequestContext context = RequestContext::Internal;
+  switch (aContentPolicyType) {
+  case nsIContentPolicy::TYPE_OTHER:
+    context = RequestContext::Internal;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_SCRIPT:
+  case nsIContentPolicy::TYPE_INTERNAL_SCRIPT_PRELOAD:
+  case nsIContentPolicy::TYPE_INTERNAL_SERVICE_WORKER:
+    context = RequestContext::Script;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_WORKER:
+    context = RequestContext::Worker;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_SHARED_WORKER:
+    context = RequestContext::Sharedworker;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_IMAGE:
+  case nsIContentPolicy::TYPE_INTERNAL_IMAGE_PRELOAD:
+  case nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON:
+    context = RequestContext::Image;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_STYLESHEET:
+  case nsIContentPolicy::TYPE_INTERNAL_STYLESHEET_PRELOAD:
+    context = RequestContext::Style;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_OBJECT:
+    context = RequestContext::Object;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_EMBED:
+    context = RequestContext::Embed;
+    break;
+  case nsIContentPolicy::TYPE_DOCUMENT:
+    context = RequestContext::Internal;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_IFRAME:
+    context = RequestContext::Iframe;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_FRAME:
+    context = RequestContext::Frame;
+    break;
+  case nsIContentPolicy::TYPE_REFRESH:
+    context = RequestContext::Internal;
+    break;
+  case nsIContentPolicy::TYPE_XBL:
+    context = RequestContext::Internal;
+    break;
+  case nsIContentPolicy::TYPE_PING:
+    context = RequestContext::Ping;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_XMLHTTPREQUEST:
+    context = RequestContext::Xmlhttprequest;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_EVENTSOURCE:
+    context = RequestContext::Eventsource;
+    break;
+  case nsIContentPolicy::TYPE_OBJECT_SUBREQUEST:
+    context = RequestContext::Plugin;
+    break;
+  case nsIContentPolicy::TYPE_DTD:
+    context = RequestContext::Internal;
+    break;
+  case nsIContentPolicy::TYPE_FONT:
+    context = RequestContext::Font;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_AUDIO:
+    context = RequestContext::Audio;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_VIDEO:
+    context = RequestContext::Video;
+    break;
+  case nsIContentPolicy::TYPE_INTERNAL_TRACK:
+    context = RequestContext::Track;
+    break;
+  case nsIContentPolicy::TYPE_WEBSOCKET:
+    context = RequestContext::Internal;
+    break;
+  case nsIContentPolicy::TYPE_CSP_REPORT:
+    context = RequestContext::Cspreport;
+    break;
+  case nsIContentPolicy::TYPE_XSLT:
+    context = RequestContext::Xslt;
+    break;
+  case nsIContentPolicy::TYPE_BEACON:
+    context = RequestContext::Beacon;
+    break;
+  case nsIContentPolicy::TYPE_FETCH:
+    context = RequestContext::Fetch;
+    break;
+  case nsIContentPolicy::TYPE_IMAGESET:
+    context = RequestContext::Imageset;
+    break;
+  case nsIContentPolicy::TYPE_WEB_MANIFEST:
+    context = RequestContext::Manifest;
+    break;
+  default:
+    MOZ_ASSERT(false, "Unhandled nsContentPolicyType value");
+    break;
+  }
+  return context;
+}
+
+// static
+bool
+InternalRequest::IsNavigationContentPolicy(nsContentPolicyType aContentPolicyType)
+{
+  // https://fetch.spec.whatwg.org/#navigation-request-context
+  //
+  // A navigation request context is one of "form", "frame", "hyperlink",
+  // "iframe", "internal" (as long as context frame type is not "none"),
+  // "location", "metarefresh", and "prerender".
+  //
+  // Note, all of these request types are effectively initiated by nsDocShell.
+  //
+  // The TYPE_REFRESH is used in some code paths for metarefresh, but will not
+  // be seen during the actual load.  Instead the new load gets a normal
+  // nsDocShell policy type.  We include it here in case this utility method
+  // is called before the load starts.
+  return aContentPolicyType == nsIContentPolicy::TYPE_DOCUMENT ||
+         aContentPolicyType == nsIContentPolicy::TYPE_SUBDOCUMENT ||
+         aContentPolicyType == nsIContentPolicy::TYPE_INTERNAL_FRAME ||
+         aContentPolicyType == nsIContentPolicy::TYPE_INTERNAL_IFRAME ||
+         aContentPolicyType == nsIContentPolicy::TYPE_REFRESH;
+}
+
+// static
+bool
+InternalRequest::IsWorkerContentPolicy(nsContentPolicyType aContentPolicyType)
+{
+  // https://fetch.spec.whatwg.org/#worker-request-context
+  //
+  // A worker request context is one of "serviceworker", "sharedworker", and
+  // "worker".
+  //
+  // Note, service workers are not included here because currently there is
+  // no way to generate a Request with a "serviceworker" RequestContext.
+  // ServiceWorker scripts cannot be intercepted.
+  return aContentPolicyType == nsIContentPolicy::TYPE_INTERNAL_WORKER ||
+         aContentPolicyType == nsIContentPolicy::TYPE_INTERNAL_SHARED_WORKER;
+}
+
+bool
+InternalRequest::IsNavigationRequest() const
+{
+  return IsNavigationContentPolicy(mContentPolicyType);
+}
+
+bool
+InternalRequest::IsWorkerRequest() const
+{
+  return IsWorkerContentPolicy(mContentPolicyType);
+}
+
+bool
+InternalRequest::IsClientRequest() const
+{
+  return IsNavigationRequest() || IsWorkerRequest();
+}
+
+// static
+RequestMode
+InternalRequest::MapChannelToRequestMode(nsIChannel* aChannel)
+{
+  MOZ_ASSERT(aChannel);
+
+  nsCOMPtr<nsILoadInfo> loadInfo;
+  MOZ_ALWAYS_SUCCEEDS(aChannel->GetLoadInfo(getter_AddRefs(loadInfo)));
+
+  nsContentPolicyType contentPolicy = loadInfo->InternalContentPolicyType();
+  if (IsNavigationContentPolicy(contentPolicy)) {
+    return RequestMode::Navigate;
+  }
+
+  // TODO: remove the worker override once securityMode is fully implemented (bug 1189945)
+  if (IsWorkerContentPolicy(contentPolicy)) {
+    return RequestMode::Same_origin;
+  }
+
+  uint32_t securityMode = loadInfo->GetSecurityMode();
+
+  switch(securityMode) {
+    case nsILoadInfo::SEC_REQUIRE_SAME_ORIGIN_DATA_INHERITS:
+    case nsILoadInfo::SEC_REQUIRE_SAME_ORIGIN_DATA_IS_BLOCKED:
+      return RequestMode::Same_origin;
+    case nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_INHERITS:
+    case nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_IS_NULL:
+      return RequestMode::No_cors;
+    case nsILoadInfo::SEC_REQUIRE_CORS_DATA_INHERITS:
+      // TODO: Check additional flag force-preflight after bug 1199693 (bug 1189945)
+      return RequestMode::Cors;
+    default:
+      // TODO: assert never reached after CorsMode flag removed (bug 1189945)
+      MOZ_ASSERT(securityMode == nsILoadInfo::SEC_NORMAL);
+      break;
+  }
+
+  // TODO: remove following code once securityMode is fully implemented (bug 1189945)
+
+  nsCOMPtr<nsIHttpChannelInternal> httpChannel = do_QueryInterface(aChannel);
+
+  uint32_t corsMode;
+  MOZ_ALWAYS_SUCCEEDS(httpChannel->GetCorsMode(&corsMode));
+  MOZ_ASSERT(corsMode != nsIHttpChannelInternal::CORS_MODE_NAVIGATE);
+
+  // This cast is valid due to static asserts in ServiceWorkerManager.cpp.
+  return static_cast<RequestMode>(corsMode);
+}
+
+// static
+RequestCredentials
+InternalRequest::MapChannelToRequestCredentials(nsIChannel* aChannel)
+{
+  MOZ_ASSERT(aChannel);
+
+  nsCOMPtr<nsILoadInfo> loadInfo;
+  MOZ_ALWAYS_SUCCEEDS(aChannel->GetLoadInfo(getter_AddRefs(loadInfo)));
+
+
+  // TODO: Remove following code after stylesheet and image support cookie policy
+  if (loadInfo->GetSecurityMode() == nsILoadInfo::SEC_NORMAL) {
+    uint32_t loadFlags;
+    aChannel->GetLoadFlags(&loadFlags);
+
+    if (loadFlags & nsIRequest::LOAD_ANONYMOUS) {
+      return RequestCredentials::Omit;
+    } else {
+      bool includeCrossOrigin;
+      nsCOMPtr<nsIHttpChannelInternal> internalChannel = do_QueryInterface(aChannel);
+
+      internalChannel->GetCorsIncludeCredentials(&includeCrossOrigin);
+      if (includeCrossOrigin) {
+        return RequestCredentials::Include;
+      }
+    }
+    return RequestCredentials::Same_origin;
+  }
+
+  uint32_t cookiePolicy = loadInfo->GetCookiePolicy();
+
+  if (cookiePolicy == nsILoadInfo::SEC_COOKIES_INCLUDE) {
+    return RequestCredentials::Include;
+  } else if (cookiePolicy == nsILoadInfo::SEC_COOKIES_OMIT) {
+    return RequestCredentials::Omit;
+  } else if (cookiePolicy == nsILoadInfo::SEC_COOKIES_SAME_ORIGIN) {
+    return RequestCredentials::Same_origin;
+  }
+
+  MOZ_ASSERT_UNREACHABLE("Unexpected cookie policy!");
+  return RequestCredentials::Same_origin;
+}
+
+void
+InternalRequest::MaybeSkipCacheIfPerformingRevalidation()
+{
+  if (mCacheMode == RequestCache::Default &&
+      mHeaders->HasRevalidationHeaders()) {
+    mCacheMode = RequestCache::No_store;
+  }
+}
+
+void
+InternalRequest::SetPrincipalInfo(UniquePtr<mozilla::ipc::PrincipalInfo> aPrincipalInfo)
+{
+  mPrincipalInfo = Move(aPrincipalInfo);
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/InternalRequest.h b/dom/fetch/InternalRequest.h
new file mode 100644
index 0000000000..84ee0bf69e
--- /dev/null
+++ b/dom/fetch/InternalRequest.h
@@ -0,0 +1,536 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_InternalRequest_h
+#define mozilla_dom_InternalRequest_h
+
+#include "mozilla/dom/HeadersBinding.h"
+#include "mozilla/dom/InternalHeaders.h"
+#include "mozilla/dom/RequestBinding.h"
+#include "mozilla/LoadTainting.h"
+#include "mozilla/net/ReferrerPolicy.h"
+
+#include "nsIContentPolicy.h"
+#include "nsIInputStream.h"
+#include "nsISupportsImpl.h"
+#ifdef DEBUG
+#include "nsIURLParser.h"
+#include "nsNetCID.h"
+#include "nsServiceManagerUtils.h"
+#endif
+
+namespace mozilla {
+
+namespace ipc {
+class PrincipalInfo;
+} // namespace ipc
+
+namespace dom {
+
+/*
+ * The mapping of RequestContext and nsContentPolicyType is currently as the
+ * following.  Note that this mapping is not perfect yet (see the TODO comments
+ * below for examples).
+ *
+ * RequestContext    | nsContentPolicyType
+ * ------------------+--------------------
+ * audio             | TYPE_INTERNAL_AUDIO
+ * beacon            | TYPE_BEACON
+ * cspreport         | TYPE_CSP_REPORT
+ * download          |
+ * embed             | TYPE_INTERNAL_EMBED
+ * eventsource       |
+ * favicon           |
+ * fetch             | TYPE_FETCH
+ * font              | TYPE_FONT
+ * form              |
+ * frame             | TYPE_INTERNAL_FRAME
+ * hyperlink         |
+ * iframe            | TYPE_INTERNAL_IFRAME
+ * image             | TYPE_INTERNAL_IMAGE, TYPE_INTERNAL_IMAGE_PRELOAD, TYPE_INTERNAL_IMAGE_FAVICON
+ * imageset          | TYPE_IMAGESET
+ * import            | Not supported by Gecko
+ * internal          | TYPE_DOCUMENT, TYPE_XBL, TYPE_OTHER
+ * location          |
+ * manifest          | TYPE_WEB_MANIFEST
+ * object            | TYPE_INTERNAL_OBJECT
+ * ping              | TYPE_PING
+ * plugin            | TYPE_OBJECT_SUBREQUEST
+ * prefetch          |
+ * script            | TYPE_INTERNAL_SCRIPT, TYPE_INTERNAL_SCRIPT_PRELOAD
+ * sharedworker      | TYPE_INTERNAL_SHARED_WORKER
+ * subresource       | Not supported by Gecko
+ * style             | TYPE_INTERNAL_STYLESHEET, TYPE_INTERNAL_STYLESHEET_PRELOAD
+ * track             | TYPE_INTERNAL_TRACK
+ * video             | TYPE_INTERNAL_VIDEO
+ * worker            | TYPE_INTERNAL_WORKER
+ * xmlhttprequest    | TYPE_INTERNAL_XMLHTTPREQUEST
+ * eventsource       | TYPE_INTERNAL_EVENTSOURCE
+ * xslt              | TYPE_XSLT
+ *
+ * TODO: Figure out if TYPE_REFRESH maps to anything useful
+ * TODO: Figure out if TYPE_DTD maps to anything useful
+ * TODO: Figure out if TYPE_WEBSOCKET maps to anything useful
+ * TODO: Add a content type for prefetch
+ * TODO: Use the content type for manifest when it becomes available
+ * TODO: Add a content type for location
+ * TODO: Add a content type for hyperlink
+ * TODO: Add a content type for form
+ * TODO: Add a content type for favicon
+ * TODO: Add a content type for download
+ */
+
+class Request;
+class IPCInternalRequest;
+
+#define kFETCH_CLIENT_REFERRER_STR "about:client"
+class InternalRequest final
+{
+  friend class Request;
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(InternalRequest)
+  InternalRequest(const nsACString& aURL, const nsACString& aFragment);
+  InternalRequest(const nsACString& aURL,
+                  const nsACString& aFragment,
+                  const nsACString& aMethod,
+                  already_AddRefed<InternalHeaders> aHeaders,
+                  RequestCache aCacheMode,
+                  RequestMode aMode,
+                  RequestRedirect aRequestRedirect,
+                  RequestCredentials aRequestCredentials,
+                  const nsAString& aReferrer,
+                  ReferrerPolicy aReferrerPolicy,
+                  nsContentPolicyType aContentPolicyType,
+                  const nsAString& aIntegrity);
+
+  explicit InternalRequest(const IPCInternalRequest& aIPCRequest);
+
+  void ToIPC(IPCInternalRequest* aIPCRequest);
+
+  already_AddRefed<InternalRequest> Clone();
+
+  void
+  GetMethod(nsCString& aMethod) const
+  {
+    aMethod.Assign(mMethod);
+  }
+
+  void
+  SetMethod(const nsACString& aMethod)
+  {
+    mMethod.Assign(aMethod);
+  }
+
+  bool
+  HasSimpleMethod() const
+  {
+    return mMethod.LowerCaseEqualsASCII("get") ||
+           mMethod.LowerCaseEqualsASCII("post") ||
+           mMethod.LowerCaseEqualsASCII("head");
+  }
+  // GetURL should get the request's current url with fragment. A request has
+  // an associated current url. It is a pointer to the last fetch URL in
+  // request's url list.
+  void
+  GetURL(nsACString& aURL) const
+  {
+    aURL.Assign(GetURLWithoutFragment());
+    if (GetFragment().IsEmpty()) {
+      return;
+    }
+    aURL.Append(NS_LITERAL_CSTRING("#"));
+    aURL.Append(GetFragment());
+  }
+
+  const nsCString&
+  GetURLWithoutFragment() const
+  {
+    MOZ_RELEASE_ASSERT(!mURLList.IsEmpty(),
+                       "Internal Request's urlList should not be empty.");
+
+    return mURLList.LastElement();
+  }
+  // AddURL should append the url into url list.
+  // Normally we strip the fragment from the URL in Request::Constructor and
+  // pass the fragment as the second argument into it.
+  // If a fragment is present in the URL it must be stripped and passed in
+  // separately.
+  void
+  AddURL(const nsACString& aURL, const nsACString& aFragment)
+  {
+    MOZ_ASSERT(!aURL.IsEmpty());
+    MOZ_ASSERT(!aURL.Contains('#'));
+
+    mURLList.AppendElement(aURL);
+
+    mFragment.Assign(aFragment);
+  }
+  // Get the URL list without their fragments.
+  void
+  GetURLListWithoutFragment(nsTArray<nsCString>& aURLList)
+  {
+    aURLList.Assign(mURLList);
+  }
+  void
+  GetReferrer(nsAString& aReferrer) const
+  {
+    aReferrer.Assign(mReferrer);
+  }
+
+  void
+  SetReferrer(const nsAString& aReferrer)
+  {
+#ifdef DEBUG
+    bool validReferrer = false;
+    if (aReferrer.IsEmpty() ||
+        aReferrer.EqualsLiteral(kFETCH_CLIENT_REFERRER_STR)) {
+      validReferrer = true;
+    } else {
+      nsCOMPtr<nsIURLParser> parser = do_GetService(NS_STDURLPARSER_CONTRACTID);
+      if (!parser) {
+        NS_WARNING("Could not get parser to validate URL!");
+      } else {
+        uint32_t schemePos;
+        int32_t schemeLen;
+        uint32_t authorityPos;
+        int32_t authorityLen;
+        uint32_t pathPos;
+        int32_t pathLen;
+
+        NS_ConvertUTF16toUTF8 ref(aReferrer);
+        nsresult rv = parser->ParseURL(ref.get(), ref.Length(),
+                                       &schemePos, &schemeLen,
+                                       &authorityPos, &authorityLen,
+                                       &pathPos, &pathLen);
+        if (NS_FAILED(rv)) {
+          NS_WARNING("Invalid referrer URL!");
+        } else if (schemeLen < 0 || authorityLen < 0) {
+          NS_WARNING("Invalid referrer URL!");
+        } else {
+          validReferrer = true;
+        }
+      }
+    }
+
+    MOZ_ASSERT(validReferrer);
+#endif
+
+    mReferrer.Assign(aReferrer);
+  }
+
+  ReferrerPolicy
+  ReferrerPolicy_() const
+  {
+    return mReferrerPolicy;
+  }
+
+  void
+  SetReferrerPolicy(ReferrerPolicy aReferrerPolicy)
+  {
+    mReferrerPolicy = aReferrerPolicy;
+  }
+
+  net::ReferrerPolicy
+  GetEnvironmentReferrerPolicy() const
+  {
+    return mEnvironmentReferrerPolicy;
+  }
+
+  void
+  SetEnvironmentReferrerPolicy(net::ReferrerPolicy aReferrerPolicy)
+  {
+    mEnvironmentReferrerPolicy = aReferrerPolicy;
+  }
+
+  bool
+  SkipServiceWorker() const
+  {
+    return mSkipServiceWorker;
+  }
+
+  void
+  SetSkipServiceWorker()
+  {
+    mSkipServiceWorker = true;
+  }
+
+  bool
+  IsSynchronous() const
+  {
+    return mSynchronous;
+  }
+
+  RequestMode
+  Mode() const
+  {
+    return mMode;
+  }
+
+  void
+  SetMode(RequestMode aMode)
+  {
+    mMode = aMode;
+  }
+
+  RequestCredentials
+  GetCredentialsMode() const
+  {
+    return mCredentialsMode;
+  }
+
+  void
+  SetCredentialsMode(RequestCredentials aCredentialsMode)
+  {
+    mCredentialsMode = aCredentialsMode;
+  }
+
+  LoadTainting
+  GetResponseTainting() const
+  {
+    return mResponseTainting;
+  }
+
+  void
+  MaybeIncreaseResponseTainting(LoadTainting aTainting)
+  {
+    if (aTainting > mResponseTainting) {
+      mResponseTainting = aTainting;
+    }
+  }
+
+  RequestCache
+  GetCacheMode() const
+  {
+    return mCacheMode;
+  }
+
+  void
+  SetCacheMode(RequestCache aCacheMode)
+  {
+    mCacheMode = aCacheMode;
+  }
+
+  RequestRedirect
+  GetRedirectMode() const
+  {
+    return mRedirectMode;
+  }
+
+  void
+  SetRedirectMode(RequestRedirect aRedirectMode)
+  {
+    mRedirectMode = aRedirectMode;
+  }
+
+  const nsString&
+  GetIntegrity() const
+  {
+    return mIntegrity;
+  }
+  void
+  SetIntegrity(const nsAString& aIntegrity)
+  {
+    MOZ_ASSERT(mIntegrity.IsEmpty());
+    mIntegrity.Assign(aIntegrity);
+  }
+  const nsCString&
+  GetFragment() const
+  {
+    return mFragment;
+  }
+
+  nsContentPolicyType
+  ContentPolicyType() const
+  {
+    return mContentPolicyType;
+  }
+  void
+  SetContentPolicyType(nsContentPolicyType aContentPolicyType);
+
+  void
+  OverrideContentPolicyType(nsContentPolicyType aContentPolicyType);
+
+  RequestContext
+  Context() const
+  {
+    return MapContentPolicyTypeToRequestContext(mContentPolicyType);
+  }
+
+  bool
+  UnsafeRequest() const
+  {
+    return mUnsafeRequest;
+  }
+
+  void
+  SetUnsafeRequest()
+  {
+    mUnsafeRequest = true;
+  }
+
+  InternalHeaders*
+  Headers()
+  {
+    return mHeaders;
+  }
+
+  bool
+  ForceOriginHeader()
+  {
+    return mForceOriginHeader;
+  }
+
+  bool
+  SameOriginDataURL() const
+  {
+    return mSameOriginDataURL;
+  }
+
+  void
+  UnsetSameOriginDataURL()
+  {
+    mSameOriginDataURL = false;
+  }
+
+  void
+  SetBody(nsIInputStream* aStream)
+  {
+    // A request's body may not be reset once set.
+    MOZ_ASSERT_IF(aStream, !mBodyStream);
+    mBodyStream = aStream;
+  }
+
+  // Will return the original stream!
+  // Use a tee or copy if you don't want to erase the original.
+  void
+  GetBody(nsIInputStream** aStream)
+  {
+    nsCOMPtr<nsIInputStream> s = mBodyStream;
+    s.forget(aStream);
+  }
+
+  // The global is used as the client for the new object.
+  already_AddRefed<InternalRequest>
+  GetRequestConstructorCopy(nsIGlobalObject* aGlobal, ErrorResult& aRv) const;
+
+  bool
+  WasCreatedByFetchEvent() const
+  {
+    return mCreatedByFetchEvent;
+  }
+
+  void
+  SetCreatedByFetchEvent()
+  {
+    mCreatedByFetchEvent = true;
+  }
+
+  void
+  ClearCreatedByFetchEvent()
+  {
+    mCreatedByFetchEvent = false;
+  }
+
+  bool
+  IsNavigationRequest() const;
+
+  bool
+  IsWorkerRequest() const;
+
+  bool
+  IsClientRequest() const;
+
+  void
+  MaybeSkipCacheIfPerformingRevalidation();
+
+  bool
+  IsContentPolicyTypeOverridden() const
+  {
+    return mContentPolicyTypeOverridden;
+  }
+
+  static RequestMode
+  MapChannelToRequestMode(nsIChannel* aChannel);
+
+  static RequestCredentials
+  MapChannelToRequestCredentials(nsIChannel* aChannel);
+
+  // Takes ownership of the principal info.
+  void
+  SetPrincipalInfo(UniquePtr<mozilla::ipc::PrincipalInfo> aPrincipalInfo);
+
+  const UniquePtr<mozilla::ipc::PrincipalInfo>&
+  GetPrincipalInfo() const
+  {
+    return mPrincipalInfo;
+  }
+
+private:
+  // Does not copy mBodyStream.  Use fallible Clone() for complete copy.
+  explicit InternalRequest(const InternalRequest& aOther);
+
+  ~InternalRequest();
+
+  static RequestContext
+  MapContentPolicyTypeToRequestContext(nsContentPolicyType aContentPolicyType);
+
+  static bool
+  IsNavigationContentPolicy(nsContentPolicyType aContentPolicyType);
+
+  static bool
+  IsWorkerContentPolicy(nsContentPolicyType aContentPolicyType);
+
+  nsCString mMethod;
+  // mURLList: a list of one or more fetch URLs
+  nsTArray<nsCString> mURLList;
+  RefPtr<InternalHeaders> mHeaders;
+  nsCOMPtr<nsIInputStream> mBodyStream;
+
+  nsContentPolicyType mContentPolicyType;
+
+  // Empty string: no-referrer
+  // "about:client": client (default)
+  // URL: an URL
+  nsString mReferrer;
+  ReferrerPolicy mReferrerPolicy;
+
+  // This will be used for request created from Window or Worker contexts
+  // In case there's no Referrer Policy in Request, this will be passed to
+  // channel.
+  // The Environment Referrer Policy should be net::ReferrerPolicy so that it
+  // could be associated with nsIHttpChannel.
+  net::ReferrerPolicy mEnvironmentReferrerPolicy;
+  RequestMode mMode;
+  RequestCredentials mCredentialsMode;
+  MOZ_INIT_OUTSIDE_CTOR LoadTainting mResponseTainting;
+  RequestCache mCacheMode;
+  RequestRedirect mRedirectMode;
+  nsString mIntegrity;
+  nsCString mFragment;
+  MOZ_INIT_OUTSIDE_CTOR bool mAuthenticationFlag;
+  MOZ_INIT_OUTSIDE_CTOR bool mForceOriginHeader;
+  MOZ_INIT_OUTSIDE_CTOR bool mPreserveContentCodings;
+  MOZ_INIT_OUTSIDE_CTOR bool mSameOriginDataURL;
+  MOZ_INIT_OUTSIDE_CTOR bool mSkipServiceWorker;
+  MOZ_INIT_OUTSIDE_CTOR bool mSynchronous;
+  MOZ_INIT_OUTSIDE_CTOR bool mUnsafeRequest;
+  MOZ_INIT_OUTSIDE_CTOR bool mUseURLCredentials;
+  // This is only set when a Request object is created by a fetch event.  We
+  // use it to check if Service Workers are simply fetching intercepted Request
+  // objects without modifying them.
+  bool mCreatedByFetchEvent = false;
+  // This is only set when Request.overrideContentPolicyType() has been set.
+  // It is illegal to pass such a Request object to a fetch() method unless
+  // if the caller has chrome privileges.
+  bool mContentPolicyTypeOverridden = false;
+
+  UniquePtr<mozilla::ipc::PrincipalInfo> mPrincipalInfo;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_InternalRequest_h
diff --git a/dom/fetch/InternalResponse.cpp b/dom/fetch/InternalResponse.cpp
new file mode 100644
index 0000000000..cb7d745972
--- /dev/null
+++ b/dom/fetch/InternalResponse.cpp
@@ -0,0 +1,261 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "InternalResponse.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/dom/InternalHeaders.h"
+#include "mozilla/dom/cache/CacheTypes.h"
+#include "mozilla/ipc/PBackgroundSharedTypes.h"
+#include "mozilla/ipc/IPCStreamUtils.h"
+#include "nsIURI.h"
+#include "nsStreamUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+InternalResponse::InternalResponse(uint16_t aStatus, const nsACString& aStatusText)
+  : mType(ResponseType::Default)
+  , mStatus(aStatus)
+  , mStatusText(aStatusText)
+  , mHeaders(new InternalHeaders(HeadersGuardEnum::Response))
+  , mBodySize(UNKNOWN_BODY_SIZE)
+{
+}
+
+already_AddRefed<InternalResponse>
+InternalResponse::FromIPC(const IPCInternalResponse& aIPCResponse)
+{
+  if (aIPCResponse.type() == ResponseType::Error) {
+    return InternalResponse::NetworkError();
+  }
+
+  RefPtr<InternalResponse> response =
+    new InternalResponse(aIPCResponse.status(),
+                         aIPCResponse.statusText());
+
+  response->SetURLList(aIPCResponse.urlList());
+
+  response->mHeaders = new InternalHeaders(aIPCResponse.headers(),
+                                           aIPCResponse.headersGuard());
+
+  response->InitChannelInfo(aIPCResponse.channelInfo());
+  if (aIPCResponse.principalInfo().type() == mozilla::ipc::OptionalPrincipalInfo::TPrincipalInfo) {
+    UniquePtr<mozilla::ipc::PrincipalInfo> info(new mozilla::ipc::PrincipalInfo(aIPCResponse.principalInfo().get_PrincipalInfo()));
+    response->SetPrincipalInfo(Move(info));
+  }
+
+  nsCOMPtr<nsIInputStream> stream = DeserializeIPCStream(aIPCResponse.body());
+  response->SetBody(stream, aIPCResponse.bodySize());
+
+  switch (aIPCResponse.type())
+  {
+    case ResponseType::Basic:
+      response = response->BasicResponse();
+      break;
+    case ResponseType::Cors:
+      response = response->CORSResponse();
+      break;
+    case ResponseType::Default:
+      break;
+    case ResponseType::Opaque:
+      response = response->OpaqueResponse();
+      break;
+    case ResponseType::Opaqueredirect:
+      response = response->OpaqueRedirectResponse();
+      break;
+    default:
+      MOZ_CRASH("Unexpected ResponseType!");
+  }
+  MOZ_ASSERT(response);
+
+  return response.forget();
+}
+
+InternalResponse::~InternalResponse()
+{
+}
+
+template void
+InternalResponse::ToIPC<PContentParent>
+  (IPCInternalResponse* aIPCResponse,
+   PContentParent* aManager,
+   UniquePtr<mozilla::ipc::AutoIPCStream>& aAutoStream);
+template void
+InternalResponse::ToIPC<nsIContentChild>
+  (IPCInternalResponse* aIPCResponse,
+   nsIContentChild* aManager,
+   UniquePtr<mozilla::ipc::AutoIPCStream>& aAutoStream);
+template void
+InternalResponse::ToIPC<mozilla::ipc::PBackgroundParent>
+  (IPCInternalResponse* aIPCResponse,
+   mozilla::ipc::PBackgroundParent* aManager,
+   UniquePtr<mozilla::ipc::AutoIPCStream>& aAutoStream);
+template void
+InternalResponse::ToIPC<mozilla::ipc::PBackgroundChild>
+  (IPCInternalResponse* aIPCResponse,
+   mozilla::ipc::PBackgroundChild* aManager,
+   UniquePtr<mozilla::ipc::AutoIPCStream>& aAutoStream);
+
+template<typename M>
+void
+InternalResponse::ToIPC(IPCInternalResponse* aIPCResponse,
+                        M* aManager,
+                        UniquePtr<mozilla::ipc::AutoIPCStream>& aAutoStream)
+{
+  MOZ_ASSERT(aIPCResponse);
+  aIPCResponse->type() = mType;
+  aIPCResponse->urlList() = mURLList;
+  aIPCResponse->status() = GetUnfilteredStatus();
+  aIPCResponse->statusText() = GetUnfilteredStatusText();
+
+  mHeaders->ToIPC(aIPCResponse->headers(), aIPCResponse->headersGuard());
+
+  aIPCResponse->channelInfo() = mChannelInfo.AsIPCChannelInfo();
+  if (mPrincipalInfo) {
+    aIPCResponse->principalInfo() = *mPrincipalInfo;
+  } else {
+    aIPCResponse->principalInfo() = void_t();
+  }
+
+  nsCOMPtr<nsIInputStream> body;
+  int64_t bodySize;
+  GetUnfilteredBody(getter_AddRefs(body), &bodySize);
+
+  if (body) {
+    aAutoStream.reset(new mozilla::ipc::AutoIPCStream(aIPCResponse->body()));
+    aAutoStream->Serialize(body, aManager);
+  } else {
+    aIPCResponse->body() = void_t();
+  }
+
+  aIPCResponse->bodySize() = bodySize;
+}
+
+already_AddRefed<InternalResponse>
+InternalResponse::Clone()
+{
+  RefPtr<InternalResponse> clone = CreateIncompleteCopy();
+
+  clone->mHeaders = new InternalHeaders(*mHeaders);
+  if (mWrappedResponse) {
+    clone->mWrappedResponse = mWrappedResponse->Clone();
+    MOZ_ASSERT(!mBody);
+    return clone.forget();
+  }
+
+  if (!mBody) {
+    return clone.forget();
+  }
+
+  nsCOMPtr<nsIInputStream> clonedBody;
+  nsCOMPtr<nsIInputStream> replacementBody;
+
+  nsresult rv = NS_CloneInputStream(mBody, getter_AddRefs(clonedBody),
+                                    getter_AddRefs(replacementBody));
+  if (NS_WARN_IF(NS_FAILED(rv))) { return nullptr; }
+
+  clone->mBody.swap(clonedBody);
+  if (replacementBody) {
+    mBody.swap(replacementBody);
+  }
+
+  return clone.forget();
+}
+
+already_AddRefed<InternalResponse>
+InternalResponse::BasicResponse()
+{
+  MOZ_ASSERT(!mWrappedResponse, "Can't BasicResponse a already wrapped response");
+  RefPtr<InternalResponse> basic = CreateIncompleteCopy();
+  basic->mType = ResponseType::Basic;
+  basic->mHeaders = InternalHeaders::BasicHeaders(Headers());
+  basic->mWrappedResponse = this;
+  return basic.forget();
+}
+
+already_AddRefed<InternalResponse>
+InternalResponse::CORSResponse()
+{
+  MOZ_ASSERT(!mWrappedResponse, "Can't CORSResponse a already wrapped response");
+  RefPtr<InternalResponse> cors = CreateIncompleteCopy();
+  cors->mType = ResponseType::Cors;
+  cors->mHeaders = InternalHeaders::CORSHeaders(Headers());
+  cors->mWrappedResponse = this;
+  return cors.forget();
+}
+
+void
+InternalResponse::SetPrincipalInfo(UniquePtr<mozilla::ipc::PrincipalInfo> aPrincipalInfo)
+{
+  mPrincipalInfo = Move(aPrincipalInfo);
+}
+
+LoadTainting
+InternalResponse::GetTainting() const
+{
+  switch (mType) {
+    case ResponseType::Cors:
+      return LoadTainting::CORS;
+    case ResponseType::Opaque:
+      return LoadTainting::Opaque;
+    default:
+      return LoadTainting::Basic;
+  }
+}
+
+already_AddRefed<InternalResponse>
+InternalResponse::Unfiltered()
+{
+  RefPtr<InternalResponse> ref = mWrappedResponse;
+  if (!ref) {
+    ref = this;
+  }
+  return ref.forget();
+}
+
+already_AddRefed<InternalResponse>
+InternalResponse::OpaqueResponse()
+{
+  MOZ_ASSERT(!mWrappedResponse, "Can't OpaqueResponse a already wrapped response");
+  RefPtr<InternalResponse> response = new InternalResponse(0, EmptyCString());
+  response->mType = ResponseType::Opaque;
+  response->mTerminationReason = mTerminationReason;
+  response->mChannelInfo = mChannelInfo;
+  if (mPrincipalInfo) {
+    response->mPrincipalInfo = MakeUnique<mozilla::ipc::PrincipalInfo>(*mPrincipalInfo);
+  }
+  response->mWrappedResponse = this;
+  return response.forget();
+}
+
+already_AddRefed<InternalResponse>
+InternalResponse::OpaqueRedirectResponse()
+{
+  MOZ_ASSERT(!mWrappedResponse, "Can't OpaqueRedirectResponse a already wrapped response");
+  MOZ_ASSERT(!mURLList.IsEmpty(), "URLList should not be emtpy for internalResponse");
+  RefPtr<InternalResponse> response = OpaqueResponse();
+  response->mType = ResponseType::Opaqueredirect;
+  response->mURLList = mURLList;
+  return response.forget();
+}
+
+already_AddRefed<InternalResponse>
+InternalResponse::CreateIncompleteCopy()
+{
+  RefPtr<InternalResponse> copy = new InternalResponse(mStatus, mStatusText);
+  copy->mType = mType;
+  copy->mTerminationReason = mTerminationReason;
+  copy->mURLList = mURLList;
+  copy->mChannelInfo = mChannelInfo;
+  if (mPrincipalInfo) {
+    copy->mPrincipalInfo = MakeUnique<mozilla::ipc::PrincipalInfo>(*mPrincipalInfo);
+  }
+  return copy.forget();
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/InternalResponse.h b/dom/fetch/InternalResponse.h
new file mode 100644
index 0000000000..35467836a0
--- /dev/null
+++ b/dom/fetch/InternalResponse.h
@@ -0,0 +1,313 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_InternalResponse_h
+#define mozilla_dom_InternalResponse_h
+
+#include "nsIInputStream.h"
+#include "nsISupportsImpl.h"
+
+#include "mozilla/dom/ResponseBinding.h"
+#include "mozilla/dom/ChannelInfo.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla {
+namespace ipc {
+class PrincipalInfo;
+class AutoIPCStream;
+} // namespace ipc
+
+namespace dom {
+
+class InternalHeaders;
+class IPCInternalResponse;
+
+class InternalResponse final
+{
+  friend class FetchDriver;
+
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(InternalResponse)
+
+  InternalResponse(uint16_t aStatus, const nsACString& aStatusText);
+
+  static already_AddRefed<InternalResponse>
+  FromIPC(const IPCInternalResponse& aIPCResponse);
+
+  template<typename M>
+  void
+  ToIPC(IPCInternalResponse* aIPCResponse,
+        M* aManager,
+        UniquePtr<mozilla::ipc::AutoIPCStream>& aAutoStream);
+
+  already_AddRefed<InternalResponse> Clone();
+
+  static already_AddRefed<InternalResponse>
+  NetworkError()
+  {
+    RefPtr<InternalResponse> response = new InternalResponse(0, EmptyCString());
+    ErrorResult result;
+    response->Headers()->SetGuard(HeadersGuardEnum::Immutable, result);
+    MOZ_ASSERT(!result.Failed());
+    response->mType = ResponseType::Error;
+    return response.forget();
+  }
+
+  already_AddRefed<InternalResponse>
+  OpaqueResponse();
+
+  already_AddRefed<InternalResponse>
+  OpaqueRedirectResponse();
+
+  already_AddRefed<InternalResponse>
+  BasicResponse();
+
+  already_AddRefed<InternalResponse>
+  CORSResponse();
+
+  ResponseType
+  Type() const
+  {
+    MOZ_ASSERT_IF(mType == ResponseType::Error, !mWrappedResponse);
+    MOZ_ASSERT_IF(mType == ResponseType::Default, !mWrappedResponse);
+    MOZ_ASSERT_IF(mType == ResponseType::Basic, mWrappedResponse);
+    MOZ_ASSERT_IF(mType == ResponseType::Cors, mWrappedResponse);
+    MOZ_ASSERT_IF(mType == ResponseType::Opaque, mWrappedResponse);
+    MOZ_ASSERT_IF(mType == ResponseType::Opaqueredirect, mWrappedResponse);
+    return mType;
+  }
+
+  bool
+  IsError() const
+  {
+    return Type() == ResponseType::Error;
+  }
+  // GetUrl should return last fetch URL in response's url list and null if
+  // response's url list is the empty list.
+  const nsCString&
+  GetURL() const
+  {
+    // Empty urlList when response is a synthetic response.
+    if (mURLList.IsEmpty()) {
+      return EmptyCString();
+    }
+    return mURLList.LastElement();
+  }
+  void
+  GetURLList(nsTArray<nsCString>& aURLList) const
+  {
+    aURLList.Assign(mURLList);
+  }
+  const nsCString&
+  GetUnfilteredURL() const
+  {
+    if (mWrappedResponse) {
+      return mWrappedResponse->GetURL();
+    }
+    return GetURL();
+  }
+  void
+  GetUnfilteredURLList(nsTArray<nsCString>& aURLList) const
+  {
+    if (mWrappedResponse) {
+      return mWrappedResponse->GetURLList(aURLList);
+    }
+
+    return GetURLList(aURLList);
+  }
+
+  void
+  SetURLList(const nsTArray<nsCString>& aURLList)
+  {
+    mURLList.Assign(aURLList);
+
+#ifdef DEBUG
+    for(uint32_t i = 0; i < mURLList.Length(); ++i) {
+      MOZ_ASSERT(mURLList[i].Find(NS_LITERAL_CSTRING("#")) == kNotFound);
+    }
+#endif
+  }
+
+  uint16_t
+  GetStatus() const
+  {
+    return mStatus;
+  }
+
+  uint16_t
+  GetUnfilteredStatus() const
+  {
+    if (mWrappedResponse) {
+      return mWrappedResponse->GetStatus();
+    }
+
+    return GetStatus();
+  }
+
+  const nsCString&
+  GetStatusText() const
+  {
+    return mStatusText;
+  }
+
+  const nsCString&
+  GetUnfilteredStatusText() const
+  {
+    if (mWrappedResponse) {
+      return mWrappedResponse->GetStatusText();
+    }
+
+    return GetStatusText();
+  }
+
+  InternalHeaders*
+  Headers()
+  {
+    return mHeaders;
+  }
+
+  InternalHeaders*
+  UnfilteredHeaders()
+  {
+    if (mWrappedResponse) {
+      return mWrappedResponse->Headers();
+    };
+
+    return Headers();
+  }
+
+  void
+  GetUnfilteredBody(nsIInputStream** aStream, int64_t* aBodySize = nullptr)
+  {
+    if (mWrappedResponse) {
+      MOZ_ASSERT(!mBody);
+      return mWrappedResponse->GetBody(aStream, aBodySize);
+    }
+    nsCOMPtr<nsIInputStream> stream = mBody;
+    stream.forget(aStream);
+    if (aBodySize) {
+      *aBodySize = mBodySize;
+    }
+  }
+
+  void
+  GetBody(nsIInputStream** aStream, int64_t* aBodySize = nullptr)
+  {
+    if (Type() == ResponseType::Opaque ||
+        Type() == ResponseType::Opaqueredirect) {
+      *aStream = nullptr;
+      if (aBodySize) {
+        *aBodySize = UNKNOWN_BODY_SIZE;
+      }
+      return;
+    }
+
+    return GetUnfilteredBody(aStream, aBodySize);
+  }
+
+  void
+  SetBody(nsIInputStream* aBody, int64_t aBodySize)
+  {
+    if (mWrappedResponse) {
+      return mWrappedResponse->SetBody(aBody, aBodySize);
+    }
+    // A request's body may not be reset once set.
+    MOZ_ASSERT(!mBody);
+    MOZ_ASSERT(mBodySize == UNKNOWN_BODY_SIZE);
+    // Check arguments.
+    MOZ_ASSERT(aBodySize == UNKNOWN_BODY_SIZE || aBodySize >= 0);
+    // If body is not given, then size must be unknown.
+    MOZ_ASSERT_IF(!aBody, aBodySize == UNKNOWN_BODY_SIZE);
+
+    mBody = aBody;
+    mBodySize = aBodySize;
+  }
+
+  void
+  InitChannelInfo(nsIChannel* aChannel)
+  {
+    mChannelInfo.InitFromChannel(aChannel);
+  }
+
+  void
+  InitChannelInfo(const mozilla::ipc::IPCChannelInfo& aChannelInfo)
+  {
+    mChannelInfo.InitFromIPCChannelInfo(aChannelInfo);
+  }
+
+  void
+  InitChannelInfo(const ChannelInfo& aChannelInfo)
+  {
+    mChannelInfo = aChannelInfo;
+  }
+
+  const ChannelInfo&
+  GetChannelInfo() const
+  {
+    return mChannelInfo;
+  }
+
+  const UniquePtr<mozilla::ipc::PrincipalInfo>&
+  GetPrincipalInfo() const
+  {
+    return mPrincipalInfo;
+  }
+
+  bool
+  IsRedirected() const
+  {
+    return mURLList.Length() > 1;
+  }
+
+  // Takes ownership of the principal info.
+  void
+  SetPrincipalInfo(UniquePtr<mozilla::ipc::PrincipalInfo> aPrincipalInfo);
+
+  LoadTainting
+  GetTainting() const;
+
+  already_AddRefed<InternalResponse>
+  Unfiltered();
+
+private:
+  ~InternalResponse();
+
+  explicit InternalResponse(const InternalResponse& aOther) = delete;
+  InternalResponse& operator=(const InternalResponse&) = delete;
+
+  // Returns an instance of InternalResponse which is a copy of this
+  // InternalResponse, except headers, body and wrapped response (if any) which
+  // are left uninitialized. Used for cloning and filtering.
+  already_AddRefed<InternalResponse> CreateIncompleteCopy();
+
+  ResponseType mType;
+  nsCString mTerminationReason;
+  // A response has an associated url list (a list of zero or more fetch URLs).
+  // Unless stated otherwise, it is the empty list. The current url is the last
+  // element in mURLlist
+  nsTArray<nsCString> mURLList;
+  const uint16_t mStatus;
+  const nsCString mStatusText;
+  RefPtr<InternalHeaders> mHeaders;
+  nsCOMPtr<nsIInputStream> mBody;
+  int64_t mBodySize;
+public:
+  static const int64_t UNKNOWN_BODY_SIZE = -1;
+private:
+  ChannelInfo mChannelInfo;
+  UniquePtr<mozilla::ipc::PrincipalInfo> mPrincipalInfo;
+
+  // For filtered responses.
+  // Cache, and SW interception should always serialize/access the underlying
+  // unfiltered headers and when deserializing, create an InternalResponse
+  // with the unfiltered headers followed by wrapping it.
+  RefPtr<InternalResponse> mWrappedResponse;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_InternalResponse_h
diff --git a/dom/fetch/Request.cpp b/dom/fetch/Request.cpp
new file mode 100644
index 0000000000..bc17afae3e
--- /dev/null
+++ b/dom/fetch/Request.cpp
@@ -0,0 +1,627 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Request.h"
+
+#include "nsIURI.h"
+#include "nsPIDOMWindow.h"
+
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/Headers.h"
+#include "mozilla/dom/Fetch.h"
+#include "mozilla/dom/FetchUtil.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/URL.h"
+#include "mozilla/dom/WorkerPrivate.h"
+#include "mozilla/Unused.h"
+
+#include "WorkerPrivate.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(Request)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(Request)
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(Request, mOwner, mHeaders)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(Request)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+Request::Request(nsIGlobalObject* aOwner, InternalRequest* aRequest)
+  : FetchBody<Request>()
+  , mOwner(aOwner)
+  , mRequest(aRequest)
+{
+  MOZ_ASSERT(aRequest->Headers()->Guard() == HeadersGuardEnum::Immutable ||
+             aRequest->Headers()->Guard() == HeadersGuardEnum::Request ||
+             aRequest->Headers()->Guard() == HeadersGuardEnum::Request_no_cors);
+  SetMimeType();
+}
+
+Request::~Request()
+{
+}
+
+// static
+bool
+Request::RequestContextEnabled(JSContext* aCx, JSObject* aObj)
+{
+  if (NS_IsMainThread()) {
+    return Preferences::GetBool("dom.requestcontext.enabled", false);
+  }
+
+  using namespace workers;
+
+  // Otherwise, check the pref via the WorkerPrivate
+  WorkerPrivate* workerPrivate = GetWorkerPrivateFromContext(aCx);
+  if (!workerPrivate) {
+    return false;
+  }
+
+  return workerPrivate->RequestContextEnabled();
+}
+
+already_AddRefed<InternalRequest>
+Request::GetInternalRequest()
+{
+  RefPtr<InternalRequest> r = mRequest;
+  return r.forget();
+}
+
+namespace {
+already_AddRefed<nsIURI>
+ParseURLFromDocument(nsIDocument* aDocument, const nsAString& aInput,
+                     ErrorResult& aRv)
+{
+  MOZ_ASSERT(aDocument);
+  MOZ_ASSERT(NS_IsMainThread());
+
+  nsCOMPtr<nsIURI> baseURI = aDocument->GetBaseURI();
+  nsCOMPtr<nsIURI> resolvedURI;
+  aRv = NS_NewURI(getter_AddRefs(resolvedURI), aInput, nullptr, baseURI);
+  if (NS_WARN_IF(aRv.Failed())) {
+    aRv.ThrowTypeError<MSG_INVALID_URL>(aInput);
+  }
+  return resolvedURI.forget();
+}
+void
+GetRequestURLFromDocument(nsIDocument* aDocument, const nsAString& aInput,
+                          nsAString& aRequestURL, nsACString& aURLfragment,
+                          ErrorResult& aRv)
+{
+  nsCOMPtr<nsIURI> resolvedURI = ParseURLFromDocument(aDocument, aInput, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+  // This fails with URIs with weird protocols, even when they are valid,
+  // so we ignore the failure
+  nsAutoCString credentials;
+  Unused << resolvedURI->GetUserPass(credentials);
+  if (!credentials.IsEmpty()) {
+    aRv.ThrowTypeError<MSG_URL_HAS_CREDENTIALS>(aInput);
+    return;
+  }
+
+  nsCOMPtr<nsIURI> resolvedURIClone;
+  // We use CloneIgnoringRef to strip away the fragment even if the original URI
+  // is immutable.
+  aRv = resolvedURI->CloneIgnoringRef(getter_AddRefs(resolvedURIClone));
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+  nsAutoCString spec;
+  aRv = resolvedURIClone->GetSpec(spec);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+  CopyUTF8toUTF16(spec, aRequestURL);
+
+  // Get the fragment from nsIURI.
+  aRv = resolvedURI->GetRef(aURLfragment);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+}
+already_AddRefed<nsIURI>
+ParseURLFromChrome(const nsAString& aInput, ErrorResult& aRv)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  nsCOMPtr<nsIURI> uri;
+  aRv = NS_NewURI(getter_AddRefs(uri), aInput, nullptr, nullptr);
+  if (NS_WARN_IF(aRv.Failed())) {
+    aRv.ThrowTypeError<MSG_INVALID_URL>(aInput);
+  }
+  return uri.forget();
+}
+void
+GetRequestURLFromChrome(const nsAString& aInput, nsAString& aRequestURL,
+                        nsACString& aURLfragment, ErrorResult& aRv)
+{
+  nsCOMPtr<nsIURI> uri = ParseURLFromChrome(aInput, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+  // This fails with URIs with weird protocols, even when they are valid,
+  // so we ignore the failure
+  nsAutoCString credentials;
+  Unused << uri->GetUserPass(credentials);
+  if (!credentials.IsEmpty()) {
+    aRv.ThrowTypeError<MSG_URL_HAS_CREDENTIALS>(aInput);
+    return;
+  }
+
+  nsCOMPtr<nsIURI> uriClone;
+  // We use CloneIgnoringRef to strip away the fragment even if the original URI
+  // is immutable.
+  aRv = uri->CloneIgnoringRef(getter_AddRefs(uriClone));
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+  nsAutoCString spec;
+  aRv = uriClone->GetSpec(spec);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+  CopyUTF8toUTF16(spec, aRequestURL);
+
+  // Get the fragment from nsIURI.
+  aRv = uri->GetRef(aURLfragment);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+}
+already_AddRefed<URL>
+ParseURLFromWorker(const GlobalObject& aGlobal, const nsAString& aInput,
+                   ErrorResult& aRv)
+{
+  workers::WorkerPrivate* worker = workers::GetCurrentThreadWorkerPrivate();
+  MOZ_ASSERT(worker);
+  worker->AssertIsOnWorkerThread();
+
+  NS_ConvertUTF8toUTF16 baseURL(worker->GetLocationInfo().mHref);
+  RefPtr<URL> url = URL::WorkerConstructor(aGlobal, aInput, baseURL, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    aRv.ThrowTypeError<MSG_INVALID_URL>(aInput);
+  }
+  return url.forget();
+}
+void
+GetRequestURLFromWorker(const GlobalObject& aGlobal, const nsAString& aInput,
+                        nsAString& aRequestURL, nsACString& aURLfragment,
+                        ErrorResult& aRv)
+{
+  RefPtr<URL> url = ParseURLFromWorker(aGlobal, aInput, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+  nsString username;
+  url->GetUsername(username, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+
+  nsString password;
+  url->GetPassword(password, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+  if (!username.IsEmpty() || !password.IsEmpty()) {
+    aRv.ThrowTypeError<MSG_URL_HAS_CREDENTIALS>(aInput);
+    return;
+  }
+  // Get the fragment from URL.
+  nsAutoString fragment;
+  url->GetHash(fragment, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+
+  // Note: URL::GetHash() includes the "#" and we want the fragment with out
+  // the hash symbol.
+  if (!fragment.IsEmpty()) {
+    CopyUTF16toUTF8(Substring(fragment, 1), aURLfragment);
+  }
+
+  url->SetHash(EmptyString(), aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+  url->Stringify(aRequestURL, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+}
+
+class ReferrerSameOriginChecker final : public workers::WorkerMainThreadRunnable
+{
+public:
+  ReferrerSameOriginChecker(workers::WorkerPrivate* aWorkerPrivate,
+                            const nsAString& aReferrerURL,
+                            nsresult& aResult)
+    : workers::WorkerMainThreadRunnable(aWorkerPrivate,
+                                        NS_LITERAL_CSTRING("Fetch :: Referrer same origin check")),
+      mReferrerURL(aReferrerURL),
+      mResult(aResult)
+  {
+    mWorkerPrivate->AssertIsOnWorkerThread();
+  }
+
+  bool
+  MainThreadRun() override
+  {
+    nsCOMPtr<nsIURI> uri;
+    if (NS_SUCCEEDED(NS_NewURI(getter_AddRefs(uri), mReferrerURL))) {
+      nsCOMPtr<nsIPrincipal> principal = mWorkerPrivate->GetPrincipal();
+      if (principal) {
+        mResult = principal->CheckMayLoad(uri, /* report */ false,
+                                          /* allowIfInheritsPrincipal */ false);
+      }
+    }
+    return true;
+  }
+
+private:
+  const nsString mReferrerURL;
+  nsresult& mResult;
+};
+
+} // namespace
+
+/*static*/ already_AddRefed<Request>
+Request::Constructor(const GlobalObject& aGlobal,
+                     const RequestOrUSVString& aInput,
+                     const RequestInit& aInit, ErrorResult& aRv)
+{
+  nsCOMPtr<nsIInputStream> temporaryBody;
+  RefPtr<InternalRequest> request;
+
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+
+  if (aInput.IsRequest()) {
+    RefPtr<Request> inputReq = &aInput.GetAsRequest();
+    nsCOMPtr<nsIInputStream> body;
+    inputReq->GetBody(getter_AddRefs(body));
+    if (inputReq->BodyUsed()) {
+      aRv.ThrowTypeError<MSG_FETCH_BODY_CONSUMED_ERROR>();
+      return nullptr;
+    }
+    if (body) {
+      temporaryBody = body;
+    }
+
+    request = inputReq->GetInternalRequest();
+  } else {
+    // aInput is USVString.
+    // We need to get url before we create a InternalRequest.
+    nsAutoString input;
+    input.Assign(aInput.GetAsUSVString());
+    nsAutoString requestURL;
+    nsCString fragment;
+    if (NS_IsMainThread()) {
+      nsIDocument* doc = GetEntryDocument();
+      if (doc) {
+        GetRequestURLFromDocument(doc, input, requestURL, fragment, aRv);
+      } else {
+        // If we don't have a document, we must assume that this is a full URL.
+        GetRequestURLFromChrome(input, requestURL, fragment, aRv);
+      }
+    } else {
+      GetRequestURLFromWorker(aGlobal, input, requestURL, fragment, aRv);
+    }
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+    request = new InternalRequest(NS_ConvertUTF16toUTF8(requestURL), fragment);
+  }
+  request = request->GetRequestConstructorCopy(global, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+  RequestMode fallbackMode = RequestMode::EndGuard_;
+  RequestCredentials fallbackCredentials = RequestCredentials::EndGuard_;
+  RequestCache fallbackCache = RequestCache::EndGuard_;
+  if (aInput.IsUSVString()) {
+    fallbackMode = RequestMode::Cors;
+    fallbackCredentials = RequestCredentials::Omit;
+    fallbackCache = RequestCache::Default;
+  }
+
+  RequestMode mode = aInit.mMode.WasPassed() ? aInit.mMode.Value() : fallbackMode;
+  RequestCredentials credentials =
+    aInit.mCredentials.WasPassed() ? aInit.mCredentials.Value()
+                                   : fallbackCredentials;
+
+  if (mode == RequestMode::Navigate ||
+      (aInit.IsAnyMemberPresent() && request->Mode() == RequestMode::Navigate)) {
+    aRv.ThrowTypeError<MSG_INVALID_REQUEST_MODE>(NS_LITERAL_STRING("navigate"));
+    return nullptr;
+  }
+
+  if (aInit.IsAnyMemberPresent()) {
+    request->SetReferrer(NS_LITERAL_STRING(kFETCH_CLIENT_REFERRER_STR));
+    request->SetReferrerPolicy(ReferrerPolicy::_empty);
+  }
+  if (aInit.mReferrer.WasPassed()) {
+    const nsString& referrer = aInit.mReferrer.Value();
+    if (referrer.IsEmpty()) {
+      request->SetReferrer(NS_LITERAL_STRING(""));
+    } else {
+      nsAutoString referrerURL;
+      if (NS_IsMainThread()) {
+        nsIDocument* doc = GetEntryDocument();
+        nsCOMPtr<nsIURI> uri;
+        if (doc) {
+          uri = ParseURLFromDocument(doc, referrer, aRv);
+        } else {
+          // If we don't have a document, we must assume that this is a full URL.
+          uri = ParseURLFromChrome(referrer, aRv);
+        }
+        if (NS_WARN_IF(aRv.Failed())) {
+          aRv.ThrowTypeError<MSG_INVALID_REFERRER_URL>(referrer);
+          return nullptr;
+        }
+        nsAutoCString spec;
+        uri->GetSpec(spec);
+        CopyUTF8toUTF16(spec, referrerURL);
+        if (!referrerURL.EqualsLiteral(kFETCH_CLIENT_REFERRER_STR)) {
+          nsCOMPtr<nsIPrincipal> principal = global->PrincipalOrNull();
+          if (principal) {
+            nsresult rv = principal->CheckMayLoad(uri, /* report */ false,
+                                                  /* allowIfInheritsPrincipal */ false);
+            if (NS_FAILED(rv)) {
+              nsAutoCString globalOrigin;
+              principal->GetOrigin(globalOrigin);
+              aRv.ThrowTypeError<MSG_CROSS_ORIGIN_REFERRER_URL>(referrer,
+                                                                NS_ConvertUTF8toUTF16(globalOrigin));
+              return nullptr;
+            }
+          }
+        }
+      } else {
+        RefPtr<URL> url = ParseURLFromWorker(aGlobal, referrer, aRv);
+        if (NS_WARN_IF(aRv.Failed())) {
+          aRv.ThrowTypeError<MSG_INVALID_REFERRER_URL>(referrer);
+          return nullptr;
+        }
+        url->Stringify(referrerURL, aRv);
+        if (NS_WARN_IF(aRv.Failed())) {
+          aRv.ThrowTypeError<MSG_INVALID_REFERRER_URL>(referrer);
+          return nullptr;
+        }
+        if (!referrerURL.EqualsLiteral(kFETCH_CLIENT_REFERRER_STR)) {
+          workers::WorkerPrivate* worker = workers::GetCurrentThreadWorkerPrivate();
+          nsresult rv = NS_OK;
+          // ReferrerSameOriginChecker uses a sync loop to get the main thread
+          // to perform the same-origin check.  Overall, on Workers this method
+          // can create 3 sync loops (two for constructing URLs and one here) so
+          // in the future we may want to optimize it all by off-loading all of
+          // this work in a single sync loop.
+          RefPtr<ReferrerSameOriginChecker> checker =
+            new ReferrerSameOriginChecker(worker, referrerURL, rv);
+          checker->Dispatch(aRv);
+          if (aRv.Failed() || NS_FAILED(rv)) {
+            aRv.ThrowTypeError<MSG_CROSS_ORIGIN_REFERRER_URL>(referrer,
+                                                              worker->GetLocationInfo().mOrigin);
+            return nullptr;
+          }
+        }
+      }
+      request->SetReferrer(referrerURL);
+    }
+  }
+
+  if (aInit.mReferrerPolicy.WasPassed()) {
+    request->SetReferrerPolicy(aInit.mReferrerPolicy.Value());
+  }
+
+  if (NS_IsMainThread()) {
+    nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(global);
+    if (window) {
+      nsCOMPtr<nsIDocument> doc;
+      doc = window->GetExtantDoc();
+      if (doc) {
+        request->SetEnvironmentReferrerPolicy(doc->GetReferrerPolicy());
+      }
+    }
+  } else {
+    workers::WorkerPrivate* worker = workers::GetCurrentThreadWorkerPrivate();
+    if (worker) {
+      worker->AssertIsOnWorkerThread();
+      request->SetEnvironmentReferrerPolicy(worker->GetReferrerPolicy());
+    }
+  }
+
+  if (mode != RequestMode::EndGuard_) {
+    request->ClearCreatedByFetchEvent();
+    request->SetMode(mode);
+  }
+
+  if (credentials != RequestCredentials::EndGuard_) {
+    request->ClearCreatedByFetchEvent();
+    request->SetCredentialsMode(credentials);
+  }
+
+  RequestCache cache = aInit.mCache.WasPassed() ?
+                       aInit.mCache.Value() : fallbackCache;
+  if (cache != RequestCache::EndGuard_) {
+    if (cache == RequestCache::Only_if_cached &&
+        request->Mode() != RequestMode::Same_origin) {
+      uint32_t t = static_cast<uint32_t>(request->Mode());
+      NS_ConvertASCIItoUTF16 modeString(RequestModeValues::strings[t].value,
+                                        RequestModeValues::strings[t].length);
+      aRv.ThrowTypeError<MSG_ONLY_IF_CACHED_WITHOUT_SAME_ORIGIN>(modeString);
+      return nullptr;
+    }
+    request->ClearCreatedByFetchEvent();
+    request->SetCacheMode(cache);
+  }
+
+  if (aInit.mRedirect.WasPassed()) {
+    request->SetRedirectMode(aInit.mRedirect.Value());
+  }
+
+  if (aInit.mIntegrity.WasPassed()) {
+    request->SetIntegrity(aInit.mIntegrity.Value());
+  }
+
+  // Request constructor step 14.
+  if (aInit.mMethod.WasPassed()) {
+    nsAutoCString method(aInit.mMethod.Value());
+
+    // Step 14.1. Disallow forbidden methods, and anything that is not a HTTP
+    // token, since HTTP states that Method may be any of the defined values or
+    // a token (extension method).
+    nsAutoCString outMethod;
+    nsresult rv = FetchUtil::GetValidRequestMethod(method, outMethod);
+    if (NS_FAILED(rv)) {
+      NS_ConvertUTF8toUTF16 label(method);
+      aRv.ThrowTypeError<MSG_INVALID_REQUEST_METHOD>(label);
+      return nullptr;
+    }
+
+    // Step 14.2
+    request->ClearCreatedByFetchEvent();
+    request->SetMethod(outMethod);
+  }
+
+  RefPtr<InternalHeaders> requestHeaders = request->Headers();
+
+  RefPtr<InternalHeaders> headers;
+  if (aInit.mHeaders.WasPassed()) {
+    RefPtr<Headers> h = Headers::Constructor(aGlobal, aInit.mHeaders.Value(), aRv);
+    if (aRv.Failed()) {
+      return nullptr;
+    }
+    request->ClearCreatedByFetchEvent();
+    headers = h->GetInternalHeaders();
+  } else {
+    headers = new InternalHeaders(*requestHeaders);
+  }
+
+  requestHeaders->Clear();
+  // From "Let r be a new Request object associated with request and a new
+  // Headers object whose guard is "request"."
+  requestHeaders->SetGuard(HeadersGuardEnum::Request, aRv);
+  MOZ_ASSERT(!aRv.Failed());
+
+  if (request->Mode() == RequestMode::No_cors) {
+    if (!request->HasSimpleMethod()) {
+      nsAutoCString method;
+      request->GetMethod(method);
+      NS_ConvertUTF8toUTF16 label(method);
+      aRv.ThrowTypeError<MSG_INVALID_REQUEST_METHOD>(label);
+      return nullptr;
+    }
+
+    if (!request->GetIntegrity().IsEmpty()) {
+      aRv.ThrowTypeError<MSG_REQUEST_INTEGRITY_METADATA_NOT_EMPTY>();
+      return nullptr;
+    }
+
+    requestHeaders->SetGuard(HeadersGuardEnum::Request_no_cors, aRv);
+    if (aRv.Failed()) {
+      return nullptr;
+    }
+  }
+
+  requestHeaders->Fill(*headers, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  if ((aInit.mBody.WasPassed() && !aInit.mBody.Value().IsNull()) ||
+      temporaryBody) {
+    // HEAD and GET are not allowed to have a body.
+    nsAutoCString method;
+    request->GetMethod(method);
+    // method is guaranteed to be uppercase due to step 14.2 above.
+    if (method.EqualsLiteral("HEAD") || method.EqualsLiteral("GET")) {
+      aRv.ThrowTypeError<MSG_NO_BODY_ALLOWED_FOR_GET_AND_HEAD>();
+      return nullptr;
+    }
+  }
+
+  if (aInit.mBody.WasPassed()) {
+    const Nullable<OwningArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams>& bodyInitNullable =
+      aInit.mBody.Value();
+    if (!bodyInitNullable.IsNull()) {
+      const OwningArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams& bodyInit =
+        bodyInitNullable.Value();
+      nsCOMPtr<nsIInputStream> stream;
+      nsAutoCString contentType;
+      uint64_t contentLengthUnused;
+      aRv = ExtractByteStreamFromBody(bodyInit,
+                                      getter_AddRefs(stream),
+                                      contentType,
+                                      contentLengthUnused);
+      if (NS_WARN_IF(aRv.Failed())) {
+        return nullptr;
+      }
+
+      temporaryBody = stream;
+
+      if (!contentType.IsVoid() &&
+          !requestHeaders->Has(NS_LITERAL_CSTRING("Content-Type"), aRv)) {
+        requestHeaders->Append(NS_LITERAL_CSTRING("Content-Type"),
+                               contentType, aRv);
+      }
+
+      if (NS_WARN_IF(aRv.Failed())) {
+        return nullptr;
+      }
+
+      request->ClearCreatedByFetchEvent();
+      request->SetBody(temporaryBody);
+    }
+  }
+
+  RefPtr<Request> domRequest = new Request(global, request);
+  domRequest->SetMimeType();
+
+  if (aInput.IsRequest()) {
+    RefPtr<Request> inputReq = &aInput.GetAsRequest();
+    nsCOMPtr<nsIInputStream> body;
+    inputReq->GetBody(getter_AddRefs(body));
+    if (body) {
+      inputReq->SetBody(nullptr);
+      inputReq->SetBodyUsed();
+    }
+  }
+  return domRequest.forget();
+}
+
+already_AddRefed<Request>
+Request::Clone(ErrorResult& aRv) const
+{
+  if (BodyUsed()) {
+    aRv.ThrowTypeError<MSG_FETCH_BODY_CONSUMED_ERROR>();
+    return nullptr;
+  }
+
+  RefPtr<InternalRequest> ir = mRequest->Clone();
+  if (!ir) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<Request> request = new Request(mOwner, ir);
+  return request.forget();
+}
+
+Headers*
+Request::Headers_()
+{
+  if (!mHeaders) {
+    mHeaders = new Headers(mOwner, mRequest->Headers());
+  }
+
+  return mHeaders;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/Request.h b/dom/fetch/Request.h
new file mode 100644
index 0000000000..d33c748122
--- /dev/null
+++ b/dom/fetch/Request.h
@@ -0,0 +1,167 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_Request_h
+#define mozilla_dom_Request_h
+
+#include "nsIContentPolicy.h"
+#include "nsISupportsImpl.h"
+#include "nsWrapperCache.h"
+
+#include "mozilla/dom/Fetch.h"
+#include "mozilla/dom/InternalRequest.h"
+// Required here due to certain WebIDL enums/classes being declared in both
+// files.
+#include "mozilla/dom/RequestBinding.h"
+
+namespace mozilla {
+namespace dom {
+
+class Headers;
+class InternalHeaders;
+class RequestOrUSVString;
+
+class Request final : public nsISupports
+                    , public FetchBody<Request>
+                    , public nsWrapperCache
+{
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(Request)
+
+public:
+  Request(nsIGlobalObject* aOwner, InternalRequest* aRequest);
+
+  static bool
+  RequestContextEnabled(JSContext* aCx, JSObject* aObj);
+
+  JSObject*
+  WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override
+  {
+    return RequestBinding::Wrap(aCx, this, aGivenProto);
+  }
+
+  void
+  GetUrl(nsAString& aUrl) const
+  {
+    nsAutoCString url;
+    mRequest->GetURL(url);
+    CopyUTF8toUTF16(url, aUrl);
+  }
+
+  void
+  GetMethod(nsCString& aMethod) const
+  {
+    aMethod = mRequest->mMethod;
+  }
+
+  RequestMode
+  Mode() const
+  {
+    return mRequest->mMode;
+  }
+
+  RequestCredentials
+  Credentials() const
+  {
+    return mRequest->mCredentialsMode;
+  }
+
+  RequestCache
+  Cache() const
+  {
+    return mRequest->GetCacheMode();
+  }
+
+  RequestRedirect
+  Redirect() const
+  {
+    return mRequest->GetRedirectMode();
+  }
+
+  void
+  GetIntegrity(nsAString& aIntegrity) const
+  {
+    aIntegrity = mRequest->GetIntegrity();
+  }
+
+  RequestContext
+  Context() const
+  {
+    return mRequest->Context();
+  }
+
+  void
+  OverrideContentPolicyType(nsContentPolicyType aContentPolicyType)
+  {
+    mRequest->OverrideContentPolicyType(aContentPolicyType);
+  }
+
+  bool
+  IsContentPolicyTypeOverridden() const
+  {
+    return mRequest->IsContentPolicyTypeOverridden();
+  }
+
+  void
+  GetReferrer(nsAString& aReferrer) const
+  {
+    mRequest->GetReferrer(aReferrer);
+  }
+
+  ReferrerPolicy
+  ReferrerPolicy_() const
+  {
+    return mRequest->ReferrerPolicy_();
+  }
+
+  InternalHeaders*
+  GetInternalHeaders() const
+  {
+    return mRequest->Headers();
+  }
+
+  Headers* Headers_();
+
+  void
+  GetBody(nsIInputStream** aStream) { return mRequest->GetBody(aStream); }
+
+  void
+  SetBody(nsIInputStream* aStream) { return mRequest->SetBody(aStream); }
+
+  static already_AddRefed<Request>
+  Constructor(const GlobalObject& aGlobal, const RequestOrUSVString& aInput,
+              const RequestInit& aInit, ErrorResult& rv);
+
+  nsIGlobalObject* GetParentObject() const
+  {
+    return mOwner;
+  }
+
+  already_AddRefed<Request>
+  Clone(ErrorResult& aRv) const;
+
+  already_AddRefed<InternalRequest>
+  GetInternalRequest();
+
+  const UniquePtr<mozilla::ipc::PrincipalInfo>&
+  GetPrincipalInfo() const
+  {
+    return mRequest->GetPrincipalInfo();
+  }
+
+private:
+  ~Request();
+
+  nsCOMPtr<nsIGlobalObject> mOwner;
+  RefPtr<InternalRequest> mRequest;
+  // Lazily created.
+  RefPtr<Headers> mHeaders;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_Request_h
diff --git a/dom/fetch/Response.cpp b/dom/fetch/Response.cpp
new file mode 100644
index 0000000000..a76071bf8c
--- /dev/null
+++ b/dom/fetch/Response.cpp
@@ -0,0 +1,281 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Response.h"
+
+#include "nsISupportsImpl.h"
+#include "nsIURI.h"
+#include "nsPIDOMWindow.h"
+
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/FetchBinding.h"
+#include "mozilla/dom/Headers.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/URL.h"
+
+#include "nsDOMString.h"
+
+#include "InternalResponse.h"
+#include "WorkerPrivate.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(Response)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(Response)
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(Response, mOwner, mHeaders)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(Response)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+Response::Response(nsIGlobalObject* aGlobal, InternalResponse* aInternalResponse)
+  : FetchBody<Response>()
+  , mOwner(aGlobal)
+  , mInternalResponse(aInternalResponse)
+{
+  MOZ_ASSERT(aInternalResponse->Headers()->Guard() == HeadersGuardEnum::Immutable ||
+             aInternalResponse->Headers()->Guard() == HeadersGuardEnum::Response);
+  SetMimeType();
+}
+
+Response::~Response()
+{
+}
+
+/* static */ already_AddRefed<Response>
+Response::Error(const GlobalObject& aGlobal)
+{
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+  RefPtr<InternalResponse> error = InternalResponse::NetworkError();
+  RefPtr<Response> r = new Response(global, error);
+  return r.forget();
+}
+
+/* static */ already_AddRefed<Response>
+Response::Redirect(const GlobalObject& aGlobal, const nsAString& aUrl,
+                   uint16_t aStatus, ErrorResult& aRv)
+{
+  nsAutoString parsedURL;
+
+  if (NS_IsMainThread()) {
+    nsCOMPtr<nsIURI> baseURI;
+    nsIDocument* doc = GetEntryDocument();
+    if (doc) {
+      baseURI = doc->GetBaseURI();
+    }
+    nsCOMPtr<nsIURI> resolvedURI;
+    aRv = NS_NewURI(getter_AddRefs(resolvedURI), aUrl, nullptr, baseURI);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+
+    nsAutoCString spec;
+    aRv = resolvedURI->GetSpec(spec);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+
+    CopyUTF8toUTF16(spec, parsedURL);
+  } else {
+    workers::WorkerPrivate* worker = workers::GetCurrentThreadWorkerPrivate();
+    MOZ_ASSERT(worker);
+    worker->AssertIsOnWorkerThread();
+
+    NS_ConvertUTF8toUTF16 baseURL(worker->GetLocationInfo().mHref);
+    RefPtr<URL> url = URL::WorkerConstructor(aGlobal, aUrl, baseURL, aRv);
+    if (aRv.Failed()) {
+      return nullptr;
+    }
+
+    url->Stringify(parsedURL, aRv);
+  }
+
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  if (aStatus != 301 && aStatus != 302 && aStatus != 303 && aStatus != 307 && aStatus != 308) {
+    aRv.ThrowRangeError<MSG_INVALID_REDIRECT_STATUSCODE_ERROR>();
+    return nullptr;
+  }
+
+  Optional<ArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams> body;
+  ResponseInit init;
+  init.mStatus = aStatus;
+  RefPtr<Response> r = Response::Constructor(aGlobal, body, init, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  r->GetInternalHeaders()->Set(NS_LITERAL_CSTRING("Location"),
+                               NS_ConvertUTF16toUTF8(parsedURL), aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+  r->GetInternalHeaders()->SetGuard(HeadersGuardEnum::Immutable, aRv);
+  MOZ_ASSERT(!aRv.Failed());
+
+  return r.forget();
+}
+
+/*static*/ already_AddRefed<Response>
+Response::Constructor(const GlobalObject& aGlobal,
+                      const Optional<ArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams>& aBody,
+                      const ResponseInit& aInit, ErrorResult& aRv)
+{
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+
+  if (aInit.mStatus < 200 || aInit.mStatus > 599) {
+    aRv.ThrowRangeError<MSG_INVALID_RESPONSE_STATUSCODE_ERROR>();
+    return nullptr;
+  }
+
+  // Check if the status text contains illegal characters
+  nsACString::const_iterator start, end;
+  aInit.mStatusText.BeginReading(start);
+  aInit.mStatusText.EndReading(end);
+  if (FindCharInReadable('\r', start, end)) {
+    aRv.ThrowTypeError<MSG_RESPONSE_INVALID_STATUSTEXT_ERROR>();
+    return nullptr;
+  }
+  // Reset iterator since FindCharInReadable advances it.
+  aInit.mStatusText.BeginReading(start);
+  if (FindCharInReadable('\n', start, end)) {
+    aRv.ThrowTypeError<MSG_RESPONSE_INVALID_STATUSTEXT_ERROR>();
+    return nullptr;
+  }
+
+  RefPtr<InternalResponse> internalResponse =
+    new InternalResponse(aInit.mStatus, aInit.mStatusText);
+
+  // Grab a valid channel info from the global so this response is 'valid' for
+  // interception.
+  if (NS_IsMainThread()) {
+    ChannelInfo info;
+    nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(global);
+    if (window) {
+      nsIDocument* doc = window->GetExtantDoc();
+      MOZ_ASSERT(doc);
+      info.InitFromDocument(doc);
+    } else {
+      info.InitFromChromeGlobal(global);
+    }
+    internalResponse->InitChannelInfo(info);
+  } else {
+    workers::WorkerPrivate* worker = workers::GetCurrentThreadWorkerPrivate();
+    MOZ_ASSERT(worker);
+    internalResponse->InitChannelInfo(worker->GetChannelInfo());
+  }
+
+  RefPtr<Response> r = new Response(global, internalResponse);
+
+  if (aInit.mHeaders.WasPassed()) {
+    internalResponse->Headers()->Clear();
+
+    // Instead of using Fill, create an object to allow the constructor to
+    // unwrap the HeadersInit.
+    RefPtr<Headers> headers =
+      Headers::Create(global, aInit.mHeaders.Value(), aRv);
+    if (aRv.Failed()) {
+      return nullptr;
+    }
+
+    internalResponse->Headers()->Fill(*headers->GetInternalHeaders(), aRv);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+  }
+
+  if (aBody.WasPassed()) {
+    if (aInit.mStatus == 204 || aInit.mStatus == 205 || aInit.mStatus == 304) {
+      aRv.ThrowTypeError<MSG_RESPONSE_NULL_STATUS_WITH_BODY>();
+      return nullptr;
+    }
+
+    nsCOMPtr<nsIInputStream> bodyStream;
+    nsCString contentType;
+    uint64_t bodySize = 0;
+    aRv = ExtractByteStreamFromBody(aBody.Value(),
+                                    getter_AddRefs(bodyStream),
+                                    contentType,
+                                    bodySize);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+    internalResponse->SetBody(bodyStream, bodySize);
+
+    if (!contentType.IsVoid() &&
+        !internalResponse->Headers()->Has(NS_LITERAL_CSTRING("Content-Type"), aRv)) {
+      // Ignore Append() failing here.
+      ErrorResult error;
+      internalResponse->Headers()->Append(NS_LITERAL_CSTRING("Content-Type"), contentType, error);
+      error.SuppressException();
+    }
+
+    if (aRv.Failed()) {
+      return nullptr;
+    }
+  }
+
+  r->SetMimeType();
+  return r.forget();
+}
+
+already_AddRefed<Response>
+Response::Clone(ErrorResult& aRv) const
+{
+  if (BodyUsed()) {
+    aRv.ThrowTypeError<MSG_FETCH_BODY_CONSUMED_ERROR>();
+    return nullptr;
+  }
+
+  RefPtr<InternalResponse> ir = mInternalResponse->Clone();
+  RefPtr<Response> response = new Response(mOwner, ir);
+  return response.forget();
+}
+
+already_AddRefed<Response>
+Response::CloneUnfiltered(ErrorResult& aRv) const
+{
+  if (BodyUsed()) {
+    aRv.ThrowTypeError<MSG_FETCH_BODY_CONSUMED_ERROR>();
+    return nullptr;
+  }
+
+  RefPtr<InternalResponse> clone = mInternalResponse->Clone();
+  RefPtr<InternalResponse> ir = clone->Unfiltered();
+  RefPtr<Response> ref = new Response(mOwner, ir);
+  return ref.forget();
+}
+
+void
+Response::SetBody(nsIInputStream* aBody, int64_t aBodySize)
+{
+  MOZ_ASSERT(!BodyUsed());
+  mInternalResponse->SetBody(aBody, aBodySize);
+}
+
+already_AddRefed<InternalResponse>
+Response::GetInternalResponse() const
+{
+  RefPtr<InternalResponse> ref = mInternalResponse;
+  return ref.forget();
+}
+
+Headers*
+Response::Headers_()
+{
+  if (!mHeaders) {
+    mHeaders = new Headers(mOwner, mInternalResponse->Headers());
+  }
+
+  return mHeaders;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/fetch/Response.h b/dom/fetch/Response.h
new file mode 100644
index 0000000000..64b3c5f451
--- /dev/null
+++ b/dom/fetch/Response.h
@@ -0,0 +1,149 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_Response_h
+#define mozilla_dom_Response_h
+
+#include "nsWrapperCache.h"
+#include "nsISupportsImpl.h"
+
+#include "mozilla/dom/Fetch.h"
+#include "mozilla/dom/ResponseBinding.h"
+
+#include "InternalHeaders.h"
+#include "InternalResponse.h"
+
+namespace mozilla {
+namespace ipc {
+class PrincipalInfo;
+} // namespace ipc
+
+namespace dom {
+
+class Headers;
+
+class Response final : public nsISupports
+                     , public FetchBody<Response>
+                     , public nsWrapperCache
+{
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(Response)
+
+public:
+  Response(nsIGlobalObject* aGlobal, InternalResponse* aInternalResponse);
+
+  Response(const Response& aOther) = delete;
+
+  JSObject*
+  WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override
+  {
+    return ResponseBinding::Wrap(aCx, this, aGivenProto);
+  }
+
+  ResponseType
+  Type() const
+  {
+    return mInternalResponse->Type();
+  }
+  void
+  GetUrl(nsAString& aUrl) const
+  {
+    CopyUTF8toUTF16(mInternalResponse->GetURL(), aUrl);
+  }
+  bool
+  Redirected() const
+  {
+    return mInternalResponse->IsRedirected();
+  }
+  uint16_t
+  Status() const
+  {
+    return mInternalResponse->GetStatus();
+  }
+
+  bool
+  Ok() const
+  {
+    return mInternalResponse->GetStatus() >= 200 &&
+           mInternalResponse->GetStatus() <= 299;
+  }
+
+  void
+  GetStatusText(nsCString& aStatusText) const
+  {
+    aStatusText = mInternalResponse->GetStatusText();
+  }
+
+  InternalHeaders*
+  GetInternalHeaders() const
+  {
+    return mInternalResponse->Headers();
+  }
+
+  void
+  InitChannelInfo(nsIChannel* aChannel)
+  {
+    mInternalResponse->InitChannelInfo(aChannel);
+  }
+
+  const ChannelInfo&
+  GetChannelInfo() const
+  {
+    return mInternalResponse->GetChannelInfo();
+  }
+
+  const UniquePtr<mozilla::ipc::PrincipalInfo>&
+  GetPrincipalInfo() const
+  {
+    return mInternalResponse->GetPrincipalInfo();
+  }
+
+  Headers* Headers_();
+
+  void
+  GetBody(nsIInputStream** aStream) { return mInternalResponse->GetBody(aStream); }
+
+  static already_AddRefed<Response>
+  Error(const GlobalObject& aGlobal);
+
+  static already_AddRefed<Response>
+  Redirect(const GlobalObject& aGlobal, const nsAString& aUrl, uint16_t aStatus, ErrorResult& aRv);
+
+  static already_AddRefed<Response>
+  Constructor(const GlobalObject& aGlobal,
+              const Optional<ArrayBufferOrArrayBufferViewOrBlobOrFormDataOrUSVStringOrURLSearchParams>& aBody,
+              const ResponseInit& aInit, ErrorResult& rv);
+
+  nsIGlobalObject* GetParentObject() const
+  {
+    return mOwner;
+  }
+
+  already_AddRefed<Response>
+  Clone(ErrorResult& aRv) const;
+
+  already_AddRefed<Response>
+  CloneUnfiltered(ErrorResult& aRv) const;
+
+  void
+  SetBody(nsIInputStream* aBody, int64_t aBodySize);
+
+  already_AddRefed<InternalResponse>
+  GetInternalResponse() const;
+
+private:
+  ~Response();
+
+  nsCOMPtr<nsIGlobalObject> mOwner;
+  RefPtr<InternalResponse> mInternalResponse;
+  // Lazily created
+  RefPtr<Headers> mHeaders;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_Response_h
diff --git a/dom/fetch/moz.build b/dom/fetch/moz.build
new file mode 100644
index 0000000000..fb2279fe7c
--- /dev/null
+++ b/dom/fetch/moz.build
@@ -0,0 +1,52 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+EXPORTS.mozilla.dom += [
+    'ChannelInfo.h',
+    'Fetch.h',
+    'FetchDriver.h',
+    'FetchIPCTypes.h',
+    'FetchUtil.h',
+    'Headers.h',
+    'InternalHeaders.h',
+    'InternalRequest.h',
+    'InternalResponse.h',
+    'Request.h',
+    'Response.h',
+]
+
+UNIFIED_SOURCES += [
+    'ChannelInfo.cpp',
+    'Fetch.cpp',
+    'FetchConsumer.cpp',
+    'FetchDriver.cpp',
+    'FetchUtil.cpp',
+    'Headers.cpp',
+    'InternalHeaders.cpp',
+    'InternalRequest.cpp',
+    'InternalResponse.cpp',
+    'Request.cpp',
+    'Response.cpp',
+]
+
+IPDL_SOURCES += [
+    'ChannelInfo.ipdlh',
+    'FetchTypes.ipdlh',
+]
+
+LOCAL_INCLUDES += [
+    '../workers',
+    # For HttpBaseChannel.h dependencies
+    '/netwerk/base',
+    # For nsDataHandler.h
+    '/netwerk/protocol/data',
+    # For HttpBaseChannel.h
+    '/netwerk/protocol/http',
+]
+
+FINAL_LIBRARY = 'xul'
+
+include('/ipc/chromium/chromium-config.mozbuild')