Add m-esr52 at 52.6.0

1 files changed, 861 insertions, 0 deletions

diff --git a/dom/base/nsWindowMemoryReporter.cpp b/dom/base/nsWindowMemoryReporter.cpp
new file mode 100644
index 0000000000..acec4acfbe
--- /dev/null
+++ b/dom/base/nsWindowMemoryReporter.cpp
@@ -0,0 +1,861 @@
+/* -*- 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 "amIAddonManager.h"
+#include "nsWindowMemoryReporter.h"
+#include "nsGlobalWindow.h"
+#include "nsIDocument.h"
+#include "nsIDOMWindowCollection.h"
+#include "nsIEffectiveTLDService.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Services.h"
+#include "mozilla/StaticPtr.h"
+#include "nsNetCID.h"
+#include "nsPrintfCString.h"
+#include "XPCJSMemoryReporter.h"
+#include "js/MemoryMetrics.h"
+#include "nsQueryObject.h"
+#include "nsServiceManagerUtils.h"
+
+using namespace mozilla;
+
+StaticRefPtr<nsWindowMemoryReporter> sWindowReporter;
+
+/**
+ * Don't trigger a ghost window check when a DOM window is detached if we've
+ * run it this recently.
+ */
+const int32_t kTimeBetweenChecks = 45; /* seconds */
+
+nsWindowMemoryReporter::nsWindowMemoryReporter()
+  : mLastCheckForGhostWindows(TimeStamp::NowLoRes()),
+    mCycleCollectorIsRunning(false),
+    mCheckTimerWaitingForCCEnd(false)
+{
+}
+
+nsWindowMemoryReporter::~nsWindowMemoryReporter()
+{
+  KillCheckTimer();
+}
+
+NS_IMPL_ISUPPORTS(nsWindowMemoryReporter, nsIMemoryReporter, nsIObserver,
+                  nsISupportsWeakReference)
+
+static nsresult
+AddNonJSSizeOfWindowAndItsDescendents(nsGlobalWindow* aWindow,
+                                      nsTabSizes* aSizes)
+{
+  // Measure the window.
+  nsWindowSizes windowSizes(moz_malloc_size_of);
+  aWindow->AddSizeOfIncludingThis(&windowSizes);
+  windowSizes.addToTabSizes(aSizes);
+
+  // Measure the inner window, if there is one.
+  nsWindowSizes innerWindowSizes(moz_malloc_size_of);
+  nsGlobalWindow* inner = aWindow->IsOuterWindow() ? aWindow->GetCurrentInnerWindowInternal()
+                                                   : nullptr;
+  if (inner) {
+    inner->AddSizeOfIncludingThis(&innerWindowSizes);
+    innerWindowSizes.addToTabSizes(aSizes);
+  }
+
+  nsCOMPtr<nsIDOMWindowCollection> frames = aWindow->GetFrames();
+
+  uint32_t length;
+  nsresult rv = frames->GetLength(&length);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Measure this window's descendents.
+  for (uint32_t i = 0; i < length; i++) {
+      nsCOMPtr<mozIDOMWindowProxy> child;
+      rv = frames->Item(i, getter_AddRefs(child));
+      NS_ENSURE_SUCCESS(rv, rv);
+      NS_ENSURE_STATE(child);
+
+      nsGlobalWindow* childWin = nsGlobalWindow::Cast(child);
+
+      rv = AddNonJSSizeOfWindowAndItsDescendents(childWin, aSizes);
+      NS_ENSURE_SUCCESS(rv, rv);
+  }
+  return NS_OK;
+}
+
+static nsresult
+NonJSSizeOfTab(nsPIDOMWindowOuter* aWindow, size_t* aDomSize, size_t* aStyleSize, size_t* aOtherSize)
+{
+  nsGlobalWindow* window = nsGlobalWindow::Cast(aWindow);
+
+  nsTabSizes sizes;
+  nsresult rv = AddNonJSSizeOfWindowAndItsDescendents(window, &sizes);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  *aDomSize   = sizes.mDom;
+  *aStyleSize = sizes.mStyle;
+  *aOtherSize = sizes.mOther;
+  return NS_OK;
+}
+
+/* static */ void
+nsWindowMemoryReporter::Init()
+{
+  MOZ_ASSERT(!sWindowReporter);
+  sWindowReporter = new nsWindowMemoryReporter();
+  ClearOnShutdown(&sWindowReporter);
+  RegisterStrongMemoryReporter(sWindowReporter);
+  RegisterNonJSSizeOfTab(NonJSSizeOfTab);
+
+  nsCOMPtr<nsIObserverService> os = services::GetObserverService();
+  if (os) {
+    os->AddObserver(sWindowReporter, "after-minimize-memory-usage",
+                    /* weakRef = */ true);
+    os->AddObserver(sWindowReporter, "cycle-collector-begin",
+                    /* weakRef = */ true);
+    os->AddObserver(sWindowReporter, "cycle-collector-end",
+                    /* weakRef = */ true);
+  }
+
+  RegisterStrongMemoryReporter(new GhostWindowsReporter());
+  RegisterGhostWindowsDistinguishedAmount(GhostWindowsReporter::DistinguishedAmount);
+}
+
+/* static */ nsWindowMemoryReporter*
+nsWindowMemoryReporter::Get()
+{
+  return sWindowReporter;
+}
+
+static already_AddRefed<nsIURI>
+GetWindowURI(nsGlobalWindow* aWindow)
+{
+  NS_ENSURE_TRUE(aWindow, nullptr);
+
+  nsCOMPtr<nsIDocument> doc = aWindow->GetExtantDoc();
+  nsCOMPtr<nsIURI> uri;
+
+  if (doc) {
+    uri = doc->GetDocumentURI();
+  }
+
+  if (!uri) {
+    nsCOMPtr<nsIScriptObjectPrincipal> scriptObjPrincipal =
+      do_QueryObject(aWindow);
+    NS_ENSURE_TRUE(scriptObjPrincipal, nullptr);
+
+    // GetPrincipal() will print a warning if the window does not have an outer
+    // window, so check here for an outer window first.  This code is
+    // functionally correct if we leave out the GetOuterWindow() check, but we
+    // end up printing a lot of warnings during debug mochitests.
+    if (aWindow->GetOuterWindow()) {
+      nsIPrincipal* principal = scriptObjPrincipal->GetPrincipal();
+      if (principal) {
+        principal->GetURI(getter_AddRefs(uri));
+      }
+    }
+  }
+
+  return uri.forget();
+}
+
+static void
+AppendWindowURI(nsGlobalWindow *aWindow, nsACString& aStr, bool aAnonymize)
+{
+  nsCOMPtr<nsIURI> uri = GetWindowURI(aWindow);
+
+  if (uri) {
+    if (aAnonymize && !aWindow->IsChromeWindow()) {
+      aStr.AppendPrintf("<anonymized-%llu>", aWindow->WindowID());
+    } else {
+      nsCString spec = uri->GetSpecOrDefault();
+
+      // A hack: replace forward slashes with '\\' so they aren't
+      // treated as path separators.  Users of the reporters
+      // (such as about:memory) have to undo this change.
+      spec.ReplaceChar('/', '\\');
+
+      aStr += spec;
+    }
+  } else {
+    // If we're unable to find a URI, we're dealing with a chrome window with
+    // no document in it (or somesuch), so we call this a "system window".
+    aStr += NS_LITERAL_CSTRING("[system]");
+  }
+}
+
+MOZ_DEFINE_MALLOC_SIZE_OF(WindowsMallocSizeOf)
+
+// The key is the window ID.
+typedef nsDataHashtable<nsUint64HashKey, nsCString> WindowPaths;
+
+static void
+ReportAmount(const nsCString& aBasePath, const char* aPathTail,
+             size_t aAmount, const nsCString& aDescription,
+             uint32_t aKind, uint32_t aUnits,
+             nsIHandleReportCallback* aHandleReport,
+             nsISupports* aData)
+{
+  if (aAmount == 0) {
+    return;
+  }
+
+  nsAutoCString path(aBasePath);
+  path += aPathTail;
+
+  aHandleReport->Callback(
+    EmptyCString(), path, aKind, aUnits, aAmount, aDescription, aData);
+}
+
+static void
+ReportSize(const nsCString& aBasePath, const char* aPathTail,
+           size_t aAmount, const nsCString& aDescription,
+           nsIHandleReportCallback* aHandleReport,
+           nsISupports* aData)
+{
+  ReportAmount(aBasePath, aPathTail, aAmount, aDescription,
+               nsIMemoryReporter::KIND_HEAP, nsIMemoryReporter::UNITS_BYTES,
+               aHandleReport, aData);
+}
+
+static void
+ReportCount(const nsCString& aBasePath, const char* aPathTail,
+            size_t aAmount, const nsCString& aDescription,
+            nsIHandleReportCallback* aHandleReport,
+            nsISupports* aData)
+{
+  ReportAmount(aBasePath, aPathTail, aAmount, aDescription,
+               nsIMemoryReporter::KIND_OTHER, nsIMemoryReporter::UNITS_COUNT,
+               aHandleReport, aData);
+}
+
+static void
+CollectWindowReports(nsGlobalWindow *aWindow,
+                     amIAddonManager *addonManager,
+                     nsWindowSizes *aWindowTotalSizes,
+                     nsTHashtable<nsUint64HashKey> *aGhostWindowIDs,
+                     WindowPaths *aWindowPaths,
+                     WindowPaths *aTopWindowPaths,
+                     nsIHandleReportCallback *aHandleReport,
+                     nsISupports *aData,
+                     bool aAnonymize)
+{
+  nsAutoCString windowPath("explicit/");
+
+  // Avoid calling aWindow->GetTop() if there's no outer window.  It will work
+  // just fine, but will spew a lot of warnings.
+  nsGlobalWindow *top = nullptr;
+  nsCOMPtr<nsIURI> location;
+  if (aWindow->GetOuterWindow()) {
+    // Our window should have a null top iff it has a null docshell.
+    MOZ_ASSERT(!!aWindow->GetTopInternal() == !!aWindow->GetDocShell());
+    top = aWindow->GetTopInternal();
+    if (top) {
+      location = GetWindowURI(top);
+    }
+  }
+  if (!location) {
+    location = GetWindowURI(aWindow);
+  }
+
+  if (addonManager && location) {
+    bool ok;
+    nsAutoCString id;
+    if (NS_SUCCEEDED(addonManager->MapURIToAddonID(location, id, &ok)) && ok) {
+      // Add-on names are not privacy-sensitive, so we can use them with
+      // impunity.
+      windowPath += NS_LITERAL_CSTRING("add-ons/") + id +
+                    NS_LITERAL_CSTRING("/");
+    }
+  }
+
+  windowPath += NS_LITERAL_CSTRING("window-objects/");
+
+  if (top) {
+    windowPath += NS_LITERAL_CSTRING("top(");
+    AppendWindowURI(top, windowPath, aAnonymize);
+    windowPath.AppendPrintf(", id=%llu)", top->WindowID());
+
+    aTopWindowPaths->Put(aWindow->WindowID(), windowPath);
+
+    windowPath += aWindow->IsFrozen() ? NS_LITERAL_CSTRING("/cached/")
+                                      : NS_LITERAL_CSTRING("/active/");
+  } else {
+    if (aGhostWindowIDs->Contains(aWindow->WindowID())) {
+      windowPath += NS_LITERAL_CSTRING("top(none)/ghost/");
+    } else {
+      windowPath += NS_LITERAL_CSTRING("top(none)/detached/");
+    }
+  }
+
+  windowPath += NS_LITERAL_CSTRING("window(");
+  AppendWindowURI(aWindow, windowPath, aAnonymize);
+  windowPath += NS_LITERAL_CSTRING(")");
+
+  // Use |windowPath|, but replace "explicit/" with "event-counts/".
+  nsCString censusWindowPath(windowPath);
+  censusWindowPath.Replace(0, strlen("explicit"), "event-counts");
+
+  // Remember the path for later.
+  aWindowPaths->Put(aWindow->WindowID(), windowPath);
+
+#define REPORT_SIZE(_pathTail, _amount, _desc) \
+  ReportSize(windowPath, _pathTail, _amount, NS_LITERAL_CSTRING(_desc), \
+             aHandleReport, aData);
+
+#define REPORT_COUNT(_pathTail, _amount, _desc) \
+  ReportCount(censusWindowPath, _pathTail, _amount, NS_LITERAL_CSTRING(_desc), \
+              aHandleReport, aData);
+
+  nsWindowSizes windowSizes(WindowsMallocSizeOf);
+  aWindow->AddSizeOfIncludingThis(&windowSizes);
+
+  REPORT_SIZE("/dom/element-nodes", windowSizes.mDOMElementNodesSize,
+              "Memory used by the element nodes in a window's DOM.");
+  aWindowTotalSizes->mDOMElementNodesSize += windowSizes.mDOMElementNodesSize;
+
+  REPORT_SIZE("/dom/text-nodes", windowSizes.mDOMTextNodesSize,
+              "Memory used by the text nodes in a window's DOM.");
+  aWindowTotalSizes->mDOMTextNodesSize += windowSizes.mDOMTextNodesSize;
+
+  REPORT_SIZE("/dom/cdata-nodes", windowSizes.mDOMCDATANodesSize,
+              "Memory used by the CDATA nodes in a window's DOM.");
+  aWindowTotalSizes->mDOMCDATANodesSize += windowSizes.mDOMCDATANodesSize;
+
+  REPORT_SIZE("/dom/comment-nodes", windowSizes.mDOMCommentNodesSize,
+              "Memory used by the comment nodes in a window's DOM.");
+  aWindowTotalSizes->mDOMCommentNodesSize += windowSizes.mDOMCommentNodesSize;
+
+  REPORT_SIZE("/dom/event-targets", windowSizes.mDOMEventTargetsSize,
+              "Memory used by the event targets table in a window's DOM, and "
+              "the objects it points to, which include XHRs.");
+  aWindowTotalSizes->mDOMEventTargetsSize += windowSizes.mDOMEventTargetsSize;
+
+  REPORT_COUNT("/dom/event-targets", windowSizes.mDOMEventTargetsCount,
+               "Number of non-node event targets in the event targets table "
+               "in a window's DOM, such as XHRs.");
+  aWindowTotalSizes->mDOMEventTargetsCount +=
+    windowSizes.mDOMEventTargetsCount;
+
+  REPORT_COUNT("/dom/event-listeners", windowSizes.mDOMEventListenersCount,
+               "Number of event listeners in a window, including event "
+               "listeners on nodes and other event targets.");
+  aWindowTotalSizes->mDOMEventListenersCount +=
+    windowSizes.mDOMEventListenersCount;
+
+  REPORT_SIZE("/dom/other", windowSizes.mDOMOtherSize,
+              "Memory used by a window's DOM that isn't measured by the "
+              "other 'dom/' numbers.");
+  aWindowTotalSizes->mDOMOtherSize += windowSizes.mDOMOtherSize;
+
+  REPORT_SIZE("/property-tables",
+              windowSizes.mPropertyTablesSize,
+              "Memory used for the property tables within a window.");
+  aWindowTotalSizes->mPropertyTablesSize += windowSizes.mPropertyTablesSize;
+
+  REPORT_SIZE("/style-sheets", windowSizes.mStyleSheetsSize,
+              "Memory used by style sheets within a window.");
+  aWindowTotalSizes->mStyleSheetsSize += windowSizes.mStyleSheetsSize;
+
+  REPORT_SIZE("/layout/pres-shell", windowSizes.mLayoutPresShellSize,
+              "Memory used by layout's PresShell, along with any structures "
+              "allocated in its arena and not measured elsewhere, "
+              "within a window.");
+  aWindowTotalSizes->mLayoutPresShellSize += windowSizes.mLayoutPresShellSize;
+
+  REPORT_SIZE("/layout/line-boxes", windowSizes.mArenaStats.mLineBoxes,
+              "Memory used by line boxes within a window.");
+  aWindowTotalSizes->mArenaStats.mLineBoxes
+    += windowSizes.mArenaStats.mLineBoxes;
+
+  REPORT_SIZE("/layout/rule-nodes", windowSizes.mArenaStats.mRuleNodes,
+              "Memory used by CSS rule nodes within a window.");
+  aWindowTotalSizes->mArenaStats.mRuleNodes
+    += windowSizes.mArenaStats.mRuleNodes;
+
+  REPORT_SIZE("/layout/style-contexts", windowSizes.mArenaStats.mStyleContexts,
+              "Memory used by style contexts within a window.");
+  aWindowTotalSizes->mArenaStats.mStyleContexts
+    += windowSizes.mArenaStats.mStyleContexts;
+
+  REPORT_SIZE("/layout/style-structs", windowSizes.mArenaStats.mStyleStructs,
+              "Memory used by style structs within a window.");
+  aWindowTotalSizes->mArenaStats.mStyleStructs
+    += windowSizes.mArenaStats.mStyleStructs;
+
+  REPORT_SIZE("/layout/style-sets", windowSizes.mLayoutStyleSetsSize,
+              "Memory used by style sets within a window.");
+  aWindowTotalSizes->mLayoutStyleSetsSize += windowSizes.mLayoutStyleSetsSize;
+
+  REPORT_SIZE("/layout/text-runs", windowSizes.mLayoutTextRunsSize,
+              "Memory used for text-runs (glyph layout) in the PresShell's "
+              "frame tree, within a window.");
+  aWindowTotalSizes->mLayoutTextRunsSize += windowSizes.mLayoutTextRunsSize;
+
+  REPORT_SIZE("/layout/pres-contexts", windowSizes.mLayoutPresContextSize,
+         "Memory used for the PresContext in the PresShell's frame "
+         "within a window.");
+  aWindowTotalSizes->mLayoutPresContextSize +=
+    windowSizes.mLayoutPresContextSize;
+
+  // There are many different kinds of frames, but it is very likely
+  // that only a few matter.  Implement a cutoff so we don't bloat
+  // about:memory with many uninteresting entries.
+  const size_t FRAME_SUNDRIES_THRESHOLD =
+    js::MemoryReportingSundriesThreshold();
+
+  size_t frameSundriesSize = 0;
+#define FRAME_ID(classname)                                             \
+  {                                                                     \
+    size_t frameSize                                                    \
+      = windowSizes.mArenaStats.FRAME_ID_STAT_FIELD(classname);         \
+    if (frameSize < FRAME_SUNDRIES_THRESHOLD) {                         \
+      frameSundriesSize += frameSize;                                   \
+    } else {                                                            \
+      REPORT_SIZE("/layout/frames/" # classname, frameSize,             \
+                  "Memory used by frames of "                           \
+                  "type " #classname " within a window.");              \
+    }                                                                   \
+    aWindowTotalSizes->mArenaStats.FRAME_ID_STAT_FIELD(classname)       \
+      += frameSize;                                                     \
+  }
+#include "nsFrameIdList.h"
+#undef FRAME_ID
+
+  if (frameSundriesSize > 0) {
+    REPORT_SIZE("/layout/frames/sundries", frameSundriesSize,
+                "The sum of all memory used by frames which were too small "
+                "to be shown individually.");
+  }
+
+#undef REPORT_SIZE
+#undef REPORT_COUNT
+}
+
+typedef nsTArray< RefPtr<nsGlobalWindow> > WindowArray;
+
+NS_IMETHODIMP
+nsWindowMemoryReporter::CollectReports(nsIHandleReportCallback* aHandleReport,
+                                       nsISupports* aData, bool aAnonymize)
+{
+  nsGlobalWindow::WindowByIdTable* windowsById =
+    nsGlobalWindow::GetWindowsTable();
+  NS_ENSURE_TRUE(windowsById, NS_OK);
+
+  // Hold on to every window in memory so that window objects can't be
+  // destroyed while we're calling the memory reporter callback.
+  WindowArray windows;
+  for (auto iter = windowsById->Iter(); !iter.Done(); iter.Next()) {
+    windows.AppendElement(iter.Data());
+  }
+
+  // Get the IDs of all the "ghost" windows, and call aHandleReport->Callback()
+  // for each one.
+  nsTHashtable<nsUint64HashKey> ghostWindows;
+  CheckForGhostWindows(&ghostWindows);
+  for (auto iter = ghostWindows.ConstIter(); !iter.Done(); iter.Next()) {
+    nsGlobalWindow::WindowByIdTable* windowsById =
+      nsGlobalWindow::GetWindowsTable();
+    if (!windowsById) {
+      NS_WARNING("Couldn't get window-by-id hashtable?");
+      continue;
+    }
+
+    nsGlobalWindow* window = windowsById->Get(iter.Get()->GetKey());
+    if (!window) {
+      NS_WARNING("Could not look up window?");
+      continue;
+    }
+
+    nsAutoCString path;
+    path.AppendLiteral("ghost-windows/");
+    AppendWindowURI(window, path, aAnonymize);
+
+    aHandleReport->Callback(
+      /* process = */ EmptyCString(),
+      path,
+      nsIMemoryReporter::KIND_OTHER,
+      nsIMemoryReporter::UNITS_COUNT,
+      /* amount = */ 1,
+      /* description = */ NS_LITERAL_CSTRING("A ghost window."),
+      aData);
+  }
+
+  WindowPaths windowPaths;
+  WindowPaths topWindowPaths;
+
+  // Collect window memory usage.
+  nsWindowSizes windowTotalSizes(nullptr);
+  nsCOMPtr<amIAddonManager> addonManager;
+  if (XRE_IsParentProcess()) {
+    // Only try to access the service from the main process.
+    addonManager = do_GetService("@mozilla.org/addons/integration;1");
+  }
+  for (uint32_t i = 0; i < windows.Length(); i++) {
+    CollectWindowReports(windows[i], addonManager,
+                         &windowTotalSizes, &ghostWindows,
+                         &windowPaths, &topWindowPaths, aHandleReport,
+                         aData, aAnonymize);
+  }
+
+  // Report JS memory usage.  We do this from here because the JS memory
+  // reporter needs to be passed |windowPaths|.
+  xpc::JSReporter::CollectReports(&windowPaths, &topWindowPaths,
+                                  aHandleReport, aData, aAnonymize);
+
+#define REPORT(_path, _amount, _desc) \
+  aHandleReport->Callback(EmptyCString(), NS_LITERAL_CSTRING(_path), \
+                          KIND_OTHER, UNITS_BYTES, _amount, \
+                          NS_LITERAL_CSTRING(_desc), aData);
+
+  REPORT("window-objects/dom/element-nodes", windowTotalSizes.mDOMElementNodesSize,
+         "This is the sum of all windows' 'dom/element-nodes' numbers.");
+
+  REPORT("window-objects/dom/text-nodes", windowTotalSizes.mDOMTextNodesSize,
+         "This is the sum of all windows' 'dom/text-nodes' numbers.");
+
+  REPORT("window-objects/dom/cdata-nodes", windowTotalSizes.mDOMCDATANodesSize,
+         "This is the sum of all windows' 'dom/cdata-nodes' numbers.");
+
+  REPORT("window-objects/dom/comment-nodes", windowTotalSizes.mDOMCommentNodesSize,
+         "This is the sum of all windows' 'dom/comment-nodes' numbers.");
+
+  REPORT("window-objects/dom/event-targets", windowTotalSizes.mDOMEventTargetsSize,
+         "This is the sum of all windows' 'dom/event-targets' numbers.");
+
+  REPORT("window-objects/dom/other", windowTotalSizes.mDOMOtherSize,
+         "This is the sum of all windows' 'dom/other' numbers.");
+
+  REPORT("window-objects/property-tables",
+         windowTotalSizes.mPropertyTablesSize,
+         "This is the sum of all windows' 'property-tables' numbers.");
+
+  REPORT("window-objects/style-sheets", windowTotalSizes.mStyleSheetsSize,
+         "This is the sum of all windows' 'style-sheets' numbers.");
+
+  REPORT("window-objects/layout/pres-shell", windowTotalSizes.mLayoutPresShellSize,
+         "This is the sum of all windows' 'layout/arenas' numbers.");
+
+  REPORT("window-objects/layout/line-boxes",
+         windowTotalSizes.mArenaStats.mLineBoxes,
+         "This is the sum of all windows' 'layout/line-boxes' numbers.");
+
+  REPORT("window-objects/layout/rule-nodes",
+         windowTotalSizes.mArenaStats.mRuleNodes,
+         "This is the sum of all windows' 'layout/rule-nodes' numbers.");
+
+  REPORT("window-objects/layout/style-contexts",
+         windowTotalSizes.mArenaStats.mStyleContexts,
+         "This is the sum of all windows' 'layout/style-contexts' numbers.");
+
+  REPORT("window-objects/layout/style-structs",
+         windowTotalSizes.mArenaStats.mStyleStructs,
+         "This is the sum of all windows' 'layout/style-structs' numbers.");
+
+  REPORT("window-objects/layout/style-sets", windowTotalSizes.mLayoutStyleSetsSize,
+         "This is the sum of all windows' 'layout/style-sets' numbers.");
+
+  REPORT("window-objects/layout/text-runs", windowTotalSizes.mLayoutTextRunsSize,
+         "This is the sum of all windows' 'layout/text-runs' numbers.");
+
+  REPORT("window-objects/layout/pres-contexts", windowTotalSizes.mLayoutPresContextSize,
+         "This is the sum of all windows' 'layout/pres-contexts' numbers.");
+
+  size_t frameTotal = 0;
+#define FRAME_ID(classname)                \
+  frameTotal += windowTotalSizes.mArenaStats.FRAME_ID_STAT_FIELD(classname);
+#include "nsFrameIdList.h"
+#undef FRAME_ID
+
+  REPORT("window-objects/layout/frames", frameTotal,
+         "Memory used for layout frames within windows. "
+         "This is the sum of all windows' 'layout/frames/' numbers.");
+
+#undef REPORT
+
+  return NS_OK;
+}
+
+uint32_t
+nsWindowMemoryReporter::GetGhostTimeout()
+{
+  return Preferences::GetUint("memory.ghost_window_timeout_seconds", 60);
+}
+
+NS_IMETHODIMP
+nsWindowMemoryReporter::Observe(nsISupports *aSubject, const char *aTopic,
+                                const char16_t *aData)
+{
+  if (!strcmp(aTopic, "after-minimize-memory-usage")) {
+    ObserveAfterMinimizeMemoryUsage();
+  } else if (!strcmp(aTopic, "cycle-collector-begin")) {
+    if (mCheckTimer) {
+      mCheckTimerWaitingForCCEnd = true;
+      KillCheckTimer();
+    }
+    mCycleCollectorIsRunning = true;
+  } else if (!strcmp(aTopic, "cycle-collector-end")) {
+    mCycleCollectorIsRunning = false;
+    if (mCheckTimerWaitingForCCEnd) {
+      mCheckTimerWaitingForCCEnd = false;
+      AsyncCheckForGhostWindows();
+    }
+  } else {
+    MOZ_ASSERT(false);
+  }
+
+  return NS_OK;
+}
+
+void
+nsWindowMemoryReporter::ObserveDOMWindowDetached(nsGlobalWindow* aWindow)
+{
+  nsWeakPtr weakWindow = do_GetWeakReference(static_cast<nsIDOMEventTarget*>(aWindow));
+  if (!weakWindow) {
+    NS_WARNING("Couldn't take weak reference to a window?");
+    return;
+  }
+
+  mDetachedWindows.Put(weakWindow, TimeStamp());
+
+  AsyncCheckForGhostWindows();
+}
+
+// static
+void
+nsWindowMemoryReporter::CheckTimerFired(nsITimer* aTimer, void* aData)
+{
+  if (sWindowReporter) {
+    MOZ_ASSERT(!sWindowReporter->mCycleCollectorIsRunning);
+    sWindowReporter->CheckForGhostWindows();
+  }
+}
+
+void
+nsWindowMemoryReporter::AsyncCheckForGhostWindows()
+{
+  if (mCheckTimer) {
+    return;
+  }
+
+  if (mCycleCollectorIsRunning) {
+    mCheckTimerWaitingForCCEnd = true;
+    return;
+  }
+
+  // If more than kTimeBetweenChecks seconds have elapsed since the last check,
+  // timerDelay is 0.  Otherwise, it is kTimeBetweenChecks, reduced by the time
+  // since the last check.  Reducing the delay by the time since the last check
+  // prevents the timer from being completely starved if it is repeatedly killed
+  // and restarted.
+  int32_t timeSinceLastCheck = (TimeStamp::NowLoRes() - mLastCheckForGhostWindows).ToSeconds();
+  int32_t timerDelay = (kTimeBetweenChecks - std::min(timeSinceLastCheck, kTimeBetweenChecks)) * PR_MSEC_PER_SEC;
+
+  mCheckTimer = do_CreateInstance("@mozilla.org/timer;1");
+
+  if (mCheckTimer) {
+    mCheckTimer->InitWithFuncCallback(CheckTimerFired, nullptr,
+                                      timerDelay, nsITimer::TYPE_ONE_SHOT);
+  }
+}
+
+void
+nsWindowMemoryReporter::ObserveAfterMinimizeMemoryUsage()
+{
+  // Someone claims they've done enough GC/CCs so that all eligible windows
+  // have been free'd.  So we deem that any windows which satisfy ghost
+  // criteria (1) and (2) now satisfy criterion (3) as well.
+  //
+  // To effect this change, we'll backdate some of our timestamps.
+
+  TimeStamp minTimeStamp = TimeStamp::Now() -
+                           TimeDuration::FromSeconds(GetGhostTimeout());
+
+  for (auto iter = mDetachedWindows.Iter(); !iter.Done(); iter.Next()) {
+    TimeStamp& timeStamp = iter.Data();
+    if (!timeStamp.IsNull() && timeStamp > minTimeStamp) {
+      timeStamp = minTimeStamp;
+    }
+  }
+}
+
+/**
+ * Iterate over mDetachedWindows and update it to reflect the current state of
+ * the world.  In particular:
+ *
+ *   - Remove weak refs to windows which no longer exist.
+ *
+ *   - Remove references to windows which are no longer detached.
+ *
+ *   - Reset the timestamp on detached windows which share a domain with a
+ *     non-detached window (they no longer meet ghost criterion (2)).
+ *
+ *   - If a window now meets ghost criterion (2) but didn't before, set its
+ *     timestamp to now.
+ *
+ * Additionally, if aOutGhostIDs is not null, fill it with the window IDs of
+ * all ghost windows we found.
+ */
+void
+nsWindowMemoryReporter::CheckForGhostWindows(
+  nsTHashtable<nsUint64HashKey> *aOutGhostIDs /* = nullptr */)
+{
+  nsCOMPtr<nsIEffectiveTLDService> tldService = do_GetService(
+    NS_EFFECTIVETLDSERVICE_CONTRACTID);
+  if (!tldService) {
+    NS_WARNING("Couldn't get TLDService.");
+    return;
+  }
+
+  nsGlobalWindow::WindowByIdTable *windowsById =
+    nsGlobalWindow::GetWindowsTable();
+  if (!windowsById) {
+    NS_WARNING("GetWindowsTable returned null");
+    return;
+  }
+
+  mLastCheckForGhostWindows = TimeStamp::NowLoRes();
+  KillCheckTimer();
+
+  nsTHashtable<nsCStringHashKey> nonDetachedWindowDomains;
+
+  // Populate nonDetachedWindowDomains.
+  for (auto iter = windowsById->Iter(); !iter.Done(); iter.Next()) {
+    // Null outer window implies null top, but calling GetTop() when there's no
+    // outer window causes us to spew debug warnings.
+    nsGlobalWindow* window = iter.UserData();
+    if (!window->GetOuterWindow() || !window->GetTopInternal()) {
+      // This window is detached, so we don't care about its domain.
+      continue;
+    }
+
+    nsCOMPtr<nsIURI> uri = GetWindowURI(window);
+    nsAutoCString domain;
+    if (uri) {
+      tldService->GetBaseDomain(uri, 0, domain);
+    }
+    nonDetachedWindowDomains.PutEntry(domain);
+  }
+
+  // Update mDetachedWindows and write the ghost window IDs into aOutGhostIDs,
+  // if it's not null.
+  uint32_t ghostTimeout = GetGhostTimeout();
+  TimeStamp now = mLastCheckForGhostWindows;
+  for (auto iter = mDetachedWindows.Iter(); !iter.Done(); iter.Next()) {
+    nsWeakPtr weakKey = do_QueryInterface(iter.Key());
+    nsCOMPtr<mozIDOMWindow> iwindow = do_QueryReferent(weakKey);
+    if (!iwindow) {
+      // The window object has been destroyed.  Stop tracking its weak ref in
+      // our hashtable.
+      iter.Remove();
+      continue;
+    }
+
+    nsPIDOMWindowInner* window = nsPIDOMWindowInner::From(iwindow);
+
+    // Avoid calling GetTop() if we have no outer window.  Nothing will break if
+    // we do, but it will spew debug output, which can cause our test logs to
+    // overflow.
+    nsCOMPtr<nsPIDOMWindowOuter> top;
+    if (window->GetOuterWindow()) {
+      top = window->GetOuterWindow()->GetTop();
+    }
+
+    if (top) {
+      // The window is no longer detached, so we no longer want to track it.
+      iter.Remove();
+      continue;
+    }
+
+    nsCOMPtr<nsIURI> uri = GetWindowURI(nsGlobalWindow::Cast(window));
+
+    nsAutoCString domain;
+    if (uri) {
+      // GetBaseDomain works fine if |uri| is null, but it outputs a warning
+      // which ends up overrunning the mochitest logs.
+      tldService->GetBaseDomain(uri, 0, domain);
+    }
+
+    TimeStamp& timeStamp = iter.Data();
+
+    if (nonDetachedWindowDomains.Contains(domain)) {
+      // This window shares a domain with a non-detached window, so reset its
+      // clock.
+      timeStamp = TimeStamp();
+    } else {
+      // This window does not share a domain with a non-detached window, so it
+      // meets ghost criterion (2).
+      if (timeStamp.IsNull()) {
+        // This may become a ghost window later; start its clock.
+        timeStamp = now;
+      } else if ((now - timeStamp).ToSeconds() > ghostTimeout) {
+        // This definitely is a ghost window, so add it to aOutGhostIDs, if
+        // that is not null.
+        if (aOutGhostIDs && window) {
+          aOutGhostIDs->PutEntry(window->WindowID());
+        }
+      }
+    }
+  }
+}
+
+NS_IMPL_ISUPPORTS(nsWindowMemoryReporter::GhostWindowsReporter,
+                  nsIMemoryReporter)
+
+/* static */ int64_t
+nsWindowMemoryReporter::GhostWindowsReporter::DistinguishedAmount()
+{
+  nsTHashtable<nsUint64HashKey> ghostWindows;
+  sWindowReporter->CheckForGhostWindows(&ghostWindows);
+  return ghostWindows.Count();
+}
+
+void
+nsWindowMemoryReporter::KillCheckTimer()
+{
+  if (mCheckTimer) {
+    mCheckTimer->Cancel();
+    mCheckTimer = nullptr;
+  }
+}
+
+#ifdef DEBUG
+/* static */ void
+nsWindowMemoryReporter::UnlinkGhostWindows()
+{
+  if (!sWindowReporter) {
+    return;
+  }
+
+  nsGlobalWindow::WindowByIdTable* windowsById =
+    nsGlobalWindow::GetWindowsTable();
+  if (!windowsById) {
+    return;
+  }
+
+  // Hold on to every window in memory so that window objects can't be
+  // destroyed while we're calling the UnlinkGhostWindows callback.
+  WindowArray windows;
+  for (auto iter = windowsById->Iter(); !iter.Done(); iter.Next()) {
+    windows.AppendElement(iter.Data());
+  }
+
+  // Get the IDs of all the "ghost" windows, and unlink them all.
+  nsTHashtable<nsUint64HashKey> ghostWindows;
+  sWindowReporter->CheckForGhostWindows(&ghostWindows);
+  for (auto iter = ghostWindows.ConstIter(); !iter.Done(); iter.Next()) {
+    nsGlobalWindow::WindowByIdTable* windowsById =
+      nsGlobalWindow::GetWindowsTable();
+    if (!windowsById) {
+      continue;
+    }
+
+    RefPtr<nsGlobalWindow> window = windowsById->Get(iter.Get()->GetKey());
+    if (window) {
+      window->RiskyUnlink();
+    }
+  }
+}
+#endif