diff -r 000000000000 -r 6474c204b198 content/base/src/DOMStringList.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/base/src/DOMStringList.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,106 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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_DOMStringList_h
+#define mozilla_dom_DOMStringList_h
+
+#include "nsISupports.h"
+#include "nsTArray.h"
+#include "nsWrapperCache.h"
+#include "nsString.h"
+
+namespace mozilla {
+namespace dom {
+
+class DOMStringList : public nsISupports,
+                      public nsWrapperCache
+{
+public:
+  DOMStringList()
+  {
+    SetIsDOMBinding();
+  }
+  virtual ~DOMStringList();
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMStringList)
+
+  virtual JSObject* WrapObject(JSContext* aCx);
+  nsISupports* GetParentObject()
+  {
+    return nullptr;
+  }
+
+  void IndexedGetter(uint32_t aIndex, bool& aFound, nsAString& aResult)
+  {
+    EnsureFresh();
+    if (aIndex < mNames.Length()) {
+      aFound = true;
+      aResult = mNames[aIndex];
+    } else {
+      aFound = false;
+    }
+  }
+
+  void Item(uint32_t aIndex, nsAString& aResult)
+  {
+    EnsureFresh();
+    if (aIndex < mNames.Length()) {
+      aResult = mNames[aIndex];
+    } else {
+      aResult.SetIsVoid(true);
+    }
+  }
+
+  uint32_t Length()
+  {
+    EnsureFresh();
+    return mNames.Length();
+  }
+
+  bool Contains(const nsAString& aString)
+  {
+    EnsureFresh();
+    return mNames.Contains(aString);
+  }
+
+  bool Add(const nsAString& aName)
+  {
+    // XXXbz mNames should really be a fallible array; otherwise this
+    // return value is meaningless.
+    return mNames.AppendElement(aName) != nullptr;
+  }
+
+  void Clear()
+  {
+    mNames.Clear();
+  }
+
+  nsTArray<nsString>& StringArray()
+  {
+    return mNames;
+  }
+
+  void CopyList(nsTArray<nsString>& aNames)
+  {
+    aNames = mNames;
+  }
+
+protected:
+  // A method that subclasses can override to modify mNames as needed
+  // before we index into it or return its length or whatnot.
+  virtual void EnsureFresh()
+  {
+  }
+
+  // XXXbz we really want this to be a fallible array, but we end up passing it
+  // to consumers who declare themselves as taking and nsTArray.  :(
+  nsTArray<nsString> mNames;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_DOMStringList_h */