1 files changed, 23 insertions, 8 deletions
diff --git a/dom/fetch/InternalHeaders.h b/dom/fetch/InternalHeaders.h
index e470666694..9a6d6dae7d 100644
--- a/dom/fetch/InternalHeaders.h
+++ b/dom/fetch/InternalHeaders.h
@@ -45,14 +45,23 @@ private:
   HeadersGuardEnum mGuard;
   nsTArray<Entry> mList;
 
+  nsTArray<Entry> mSortedList;
+
+  // This boolean is set to true at any writing operation to mList. It's set to
+  // false when mSortedList is regenerated. This happens when the header is
+  // iterated.
+  bool mListDirty;
+
 public:
   explicit InternalHeaders(HeadersGuardEnum aGuard = HeadersGuardEnum::None)
     : mGuard(aGuard)
+    , mListDirty(false)
   {
   }
 
   explicit InternalHeaders(const InternalHeaders& aOther)
     : mGuard(HeadersGuardEnum::None)
+    , mListDirty(true)
   {
     ErrorResult result;
     Fill(aOther, result);
@@ -79,19 +88,22 @@ public:
   bool Has(const nsACString& aName, ErrorResult& aRv) const;
   void Set(const nsACString& aName, const nsACString& aValue, ErrorResult& aRv);
 
-  uint32_t GetIterableLength() const
+  uint32_t GetIterableLength()
   {
-    return mList.Length();
+    MaybeSortList();
+    return mSortedList.Length();
   }
-  const NS_ConvertASCIItoUTF16 GetKeyAtIndex(unsigned aIndex) const
+  const NS_ConvertASCIItoUTF16 GetKeyAtIndex(unsigned aIndex)
   {
-    MOZ_ASSERT(aIndex < mList.Length());
-    return NS_ConvertASCIItoUTF16(mList[aIndex].mName);
+    MaybeSortList();
+    MOZ_ASSERT(aIndex < mSortedList.Length());
+    return NS_ConvertASCIItoUTF16(mSortedList[aIndex].mName);
   }
-  const NS_ConvertASCIItoUTF16 GetValueAtIndex(unsigned aIndex) const
+  const NS_ConvertASCIItoUTF16 GetValueAtIndex(unsigned aIndex)
   {
-    MOZ_ASSERT(aIndex < mList.Length());
-    return NS_ConvertASCIItoUTF16(mList[aIndex].mValue);
+    MaybeSortList();
+    MOZ_ASSERT(aIndex < mSortedList.Length());
+    return NS_ConvertASCIItoUTF16(mSortedList[aIndex].mValue);
   }
 
   void Clear();
@@ -152,6 +164,9 @@ private:
                              const nsACString& aValue);
 
   static bool IsRevalidationHeader(const nsACString& aName);
+
+  void MaybeSortList();
+  void SetListDirty();
 };
 
 } // namespace dom