diff --git a/content/base/public/nsHostObjectProtocolHandler.h b/content/base/public/nsHostObjectProtocolHandler.h
index 0e8b334025ef..8df8c7db228f 100644
--- a/content/base/public/nsHostObjectProtocolHandler.h
+++ b/content/base/public/nsHostObjectProtocolHandler.h
@@ -18,10 +18,10 @@
 #define RTSPURI_SCHEME "rtsp"
 
 class nsIDOMBlob;
+class nsIDOMMediaStream;
 class nsIPrincipal;
 
 namespace mozilla {
-class DOMMediaStream;
 namespace dom {
 class MediaSource;
 }
@@ -122,7 +122,7 @@ extern nsresult
 NS_GetStreamForBlobURI(nsIURI* aURI, nsIInputStream** aStream);
 
 extern nsresult
-NS_GetStreamForMediaStreamURI(nsIURI* aURI, mozilla::DOMMediaStream** aStream);
+NS_GetStreamForMediaStreamURI(nsIURI* aURI, nsIDOMMediaStream** aStream);
 
 extern nsresult
 NS_GetSourceForMediaSourceURI(nsIURI* aURI, mozilla::dom::MediaSource** aSource);
diff --git a/content/base/src/nsHostObjectProtocolHandler.cpp b/content/base/src/nsHostObjectProtocolHandler.cpp
index 70d7b2311a5b..9956c383999a 100644
--- a/content/base/src/nsHostObjectProtocolHandler.cpp
+++ b/content/base/src/nsHostObjectProtocolHandler.cpp
@@ -11,7 +11,7 @@
 #include "nsNetUtil.h"
 #include "nsIPrincipal.h"
 #include "nsDOMFile.h"
-#include "DOMMediaStream.h"
+#include "nsIDOMMediaStream.h"
 #include "mozilla/dom/MediaSource.h"
 #include "nsIMemoryReporter.h"
 #include "mozilla/Preferences.h"
@@ -24,7 +24,7 @@ using mozilla::LoadInfo;
 // Hash table
 struct DataInfo
 {
-  // mObject is expected to be an nsIDOMBlob, DOMMediaStream, or MediaSource
+  // mObject is expected to be an nsIDOMBlob, nsIDOMMediaStream, or MediaSource
   nsCOMPtr<nsISupports> mObject;
   nsCOMPtr<nsIPrincipal> mPrincipal;
   nsCString mStack;
@@ -605,17 +605,20 @@ NS_GetStreamForBlobURI(nsIURI* aURI, nsIInputStream** aStream)
 }
 
 nsresult
-NS_GetStreamForMediaStreamURI(nsIURI* aURI, mozilla::DOMMediaStream** aStream)
+NS_GetStreamForMediaStreamURI(nsIURI* aURI, nsIDOMMediaStream** aStream)
 {
   NS_ASSERTION(IsMediaStreamURI(aURI), "Only call this with mediastream URIs");
 
   *aStream = nullptr;
 
-  nsresult rv = CallQueryInterface(GetDataObject(aURI), aStream);
-  if (NS_FAILED(rv)) {
+  nsCOMPtr<nsIDOMMediaStream> stream = do_QueryInterface(GetDataObject(aURI));
+  if (!stream) {
     return NS_ERROR_DOM_BAD_URI;
   }
-  return rv;
+
+  *aStream = stream;
+  NS_ADDREF(*aStream);
+  return NS_OK;
 }
 
 NS_IMETHODIMP
diff --git a/content/html/content/public/HTMLMediaElement.h b/content/html/content/public/HTMLMediaElement.h
index c27fc7d99429..923dde489e93 100755
--- a/content/html/content/public/HTMLMediaElement.h
+++ b/content/html/content/public/HTMLMediaElement.h
@@ -527,7 +527,6 @@ public:
   already_AddRefed<DOMMediaStream> GetMozSrcObject() const;
 
   void SetMozSrcObject(DOMMediaStream& aValue);
-  void SetMozSrcObject(DOMMediaStream* aValue);
 
   bool MozPreservesPitch() const
   {
diff --git a/content/html/content/src/HTMLMediaElement.cpp b/content/html/content/src/HTMLMediaElement.cpp
index eada45937e70..91f47a39d5eb 100755
--- a/content/html/content/src/HTMLMediaElement.cpp
+++ b/content/html/content/src/HTMLMediaElement.cpp
@@ -509,6 +509,14 @@ HTMLMediaElement::GetMozSrcObject() const
   return stream.forget();
 }
 
+NS_IMETHODIMP
+HTMLMediaElement::GetMozSrcObject(nsIDOMMediaStream** aStream)
+{
+  nsRefPtr<DOMMediaStream> stream = GetMozSrcObject();
+  stream.forget(aStream);
+  return NS_OK;
+}
+
 void
 HTMLMediaElement::SetMozSrcObject(DOMMediaStream& aValue)
 {
@@ -516,10 +524,12 @@ HTMLMediaElement::SetMozSrcObject(DOMMediaStream& aValue)
   Load();
 }
 
-void
-HTMLMediaElement::SetMozSrcObject(DOMMediaStream* aValue)
+NS_IMETHODIMP
+HTMLMediaElement::SetMozSrcObject(nsIDOMMediaStream* aStream)
 {
-  SetMozSrcObject(*aValue);
+  DOMMediaStream* stream = static_cast<DOMMediaStream*>(aStream);
+  SetMozSrcObject(*stream);
+  return NS_OK;
 }
 
 /* readonly attribute nsIDOMHTMLMediaElement mozAutoplayEnabled; */
@@ -1134,7 +1144,7 @@ nsresult HTMLMediaElement::LoadResource()
   }
 
   if (IsMediaStreamURI(mLoadingSrc)) {
-    nsRefPtr<DOMMediaStream> stream;
+    nsCOMPtr<nsIDOMMediaStream> stream;
     rv = NS_GetStreamForMediaStreamURI(mLoadingSrc, getter_AddRefs(stream));
     if (NS_FAILED(rv)) {
       nsCString specUTF8;
@@ -1144,7 +1154,7 @@ nsresult HTMLMediaElement::LoadResource()
       ReportLoadError("MediaLoadInvalidURI", params, ArrayLength(params));
       return rv;
     }
-    SetupSrcMediaStreamPlayback(stream);
+    SetupSrcMediaStreamPlayback(static_cast<DOMMediaStream*>(stream.get()));
     return NS_OK;
   }
 
@@ -1863,6 +1873,13 @@ HTMLMediaElement::MozCaptureStream(ErrorResult& aRv)
   return stream.forget();
 }
 
+NS_IMETHODIMP HTMLMediaElement::MozCaptureStream(nsIDOMMediaStream** aStream)
+{
+  ErrorResult rv;
+  *aStream = MozCaptureStream(rv).take();
+  return rv.ErrorCode();
+}
+
 already_AddRefed<DOMMediaStream>
 HTMLMediaElement::MozCaptureStreamUntilEnded(ErrorResult& aRv)
 {
@@ -1875,6 +1892,13 @@ HTMLMediaElement::MozCaptureStreamUntilEnded(ErrorResult& aRv)
   return stream.forget();
 }
 
+NS_IMETHODIMP HTMLMediaElement::MozCaptureStreamUntilEnded(nsIDOMMediaStream** aStream)
+{
+  ErrorResult rv;
+  *aStream = MozCaptureStreamUntilEnded(rv).take();
+  return rv.ErrorCode();
+}
+
 NS_IMETHODIMP HTMLMediaElement::GetMozAudioCaptured(bool* aCaptured)
 {
   *aCaptured = MozAudioCaptured();
diff --git a/content/media/DOMMediaStream.cpp b/content/media/DOMMediaStream.cpp
index b6fcace53396..5fee7364fba1 100644
--- a/content/media/DOMMediaStream.cpp
+++ b/content/media/DOMMediaStream.cpp
@@ -19,20 +19,34 @@
 using namespace mozilla;
 using namespace mozilla::dom;
 
-NS_IMPL_CYCLE_COLLECTION_INHERITED(DOMMediaStream,
-                                   DOMEventTargetHelper,
-                                   mWindow,
-                                   mTracks,
-                                   mConsumersToKeepAlive);
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(DOMMediaStream)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+  NS_INTERFACE_MAP_ENTRY(nsIDOMMediaStream)
+NS_INTERFACE_MAP_END
 
-NS_IMPL_ADDREF_INHERITED(DOMMediaStream, DOMEventTargetHelper)
-NS_IMPL_RELEASE_INHERITED(DOMMediaStream, DOMEventTargetHelper)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(DOMMediaStream)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(DOMMediaStream)
 
-NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(DOMMediaStream)
-  NS_INTERFACE_MAP_ENTRY(DOMMediaStream)
-NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
+NS_IMPL_CYCLE_COLLECTION_CLASS(DOMMediaStream)
 
-NS_IMPL_ISUPPORTS_INHERITED0(DOMLocalMediaStream, DOMMediaStream)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(DOMMediaStream)
+  tmp->Destroy();
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mWindow)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mTracks)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mConsumersToKeepAlive)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(DOMMediaStream)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mWindow)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mTracks)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mConsumersToKeepAlive)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(DOMMediaStream)
+
+NS_IMPL_ISUPPORTS_INHERITED(DOMLocalMediaStream, DOMMediaStream,
+                            nsIDOMLocalMediaStream)
 
 NS_IMPL_CYCLE_COLLECTION_INHERITED(DOMAudioNodeMediaStream, DOMMediaStream,
                                    mStreamNode)
@@ -79,12 +93,8 @@ public:
         track = stream->GetDOMTrackFor(mID);
       }
       if (mEvents & MediaStreamListener::TRACK_EVENT_ENDED) {
-        if (track) {
-          track->NotifyEnded();
-          stream->NotifyMediaStreamTrackEnded(track);
-        } else {
-          NS_ERROR("track ended but not found");
-        }
+        track->NotifyEnded();
+        stream->NotifyMediaStreamTrackEnded(track);
       }
       return NS_OK;
     }
diff --git a/content/media/DOMMediaStream.h b/content/media/DOMMediaStream.h
index 66aecc16bbc5..c5a82d4b12be 100644
--- a/content/media/DOMMediaStream.h
+++ b/content/media/DOMMediaStream.h
@@ -6,13 +6,13 @@
 #ifndef NSDOMMEDIASTREAM_H_
 #define NSDOMMEDIASTREAM_H_
 
+#include "nsIDOMMediaStream.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsWrapperCache.h"
 #include "StreamBuffer.h"
 #include "nsIDOMWindow.h"
 #include "nsIPrincipal.h"
 #include "mozilla/PeerIdentity.h"
-#include "mozilla/DOMEventTargetHelper.h"
 
 class nsXPCClassInfo;
 
@@ -48,14 +48,11 @@ class MediaTrackListListener;
 
 class MediaStreamDirectListener;
 
-#define NS_DOMMEDIASTREAM_IID \
-{ 0x8cb65468, 0x66c0, 0x444e, \
-  { 0x89, 0x9f, 0x89, 0x1d, 0x9e, 0xd2, 0xbe, 0x7c } }
-
 /**
  * DOM wrapper for MediaStreams.
  */
-class DOMMediaStream : public DOMEventTargetHelper
+class DOMMediaStream : public nsIDOMMediaStream,
+                       public nsWrapperCache
 {
   friend class DOMLocalMediaStream;
   typedef dom::MediaStreamTrack MediaStreamTrack;
@@ -72,11 +69,8 @@ public:
 
   DOMMediaStream();
 
-  NS_DECL_ISUPPORTS_INHERITED
-  NS_REALLY_FORWARD_NSIDOMEVENTTARGET(DOMEventTargetHelper)
-  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(DOMMediaStream,
-                                           DOMEventTargetHelper)
-  NS_DECLARE_STATIC_IID_ACCESSOR(NS_DOMMEDIASTREAM_IID)
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMMediaStream)
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
 
   nsIDOMWindow* GetParentObject() const
   {
@@ -299,20 +293,13 @@ private:
   nsAutoPtr<PeerIdentity> mPeerIdentity;
 };
 
-NS_DEFINE_STATIC_IID_ACCESSOR(DOMMediaStream,
-                              NS_DOMMEDIASTREAM_IID)
-
-#define NS_DOMLOCALMEDIASTREAM_IID \
-{ 0xb1437260, 0xec61, 0x4dfa, \
-  { 0x92, 0x54, 0x04, 0x44, 0xe2, 0xb5, 0x94, 0x9c } }
-
-class DOMLocalMediaStream : public DOMMediaStream
+class DOMLocalMediaStream : public DOMMediaStream,
+                            public nsIDOMLocalMediaStream
 {
 public:
   DOMLocalMediaStream() {}
 
   NS_DECL_ISUPPORTS_INHERITED
-  NS_DECLARE_STATIC_IID_ACCESSOR(NS_DOMLOCALMEDIASTREAM_IID)
 
   virtual JSObject* WrapObject(JSContext* aCx) MOZ_OVERRIDE;
 
@@ -336,9 +323,6 @@ protected:
   virtual ~DOMLocalMediaStream();
 };
 
-NS_DEFINE_STATIC_IID_ACCESSOR(DOMLocalMediaStream,
-                              NS_DOMLOCALMEDIASTREAM_IID)
-
 class DOMAudioNodeMediaStream : public DOMMediaStream
 {
   typedef dom::AudioNode AudioNode;
diff --git a/content/media/webspeech/recognition/SpeechRecognition.cpp b/content/media/webspeech/recognition/SpeechRecognition.cpp
index 1092e2f17ba4..490f258f40cf 100644
--- a/content/media/webspeech/recognition/SpeechRecognition.cpp
+++ b/content/media/webspeech/recognition/SpeechRecognition.cpp
@@ -935,11 +935,8 @@ NS_IMPL_ISUPPORTS(SpeechRecognition::GetUserMediaSuccessCallback, nsIDOMGetUserM
 NS_IMETHODIMP
 SpeechRecognition::GetUserMediaSuccessCallback::OnSuccess(nsISupports* aStream)
 {
-  DOMLocalMediaStream *localStream = nullptr;
-  nsresult rv = CallQueryInterface(aStream, &localStream);
-  if (NS_SUCCEEDED(rv)) {
-    mRecognition->StartRecording(localStream);
-  }
+  nsCOMPtr<nsIDOMLocalMediaStream> localStream = do_QueryInterface(aStream);
+  mRecognition->StartRecording(static_cast<DOMLocalMediaStream*>(localStream.get()));
   return NS_OK;
 }
 
diff --git a/dom/interfaces/html/nsIDOMHTMLMediaElement.idl b/dom/interfaces/html/nsIDOMHTMLMediaElement.idl
index d7012347f28e..5ff618ba5f7f 100644
--- a/dom/interfaces/html/nsIDOMHTMLMediaElement.idl
+++ b/dom/interfaces/html/nsIDOMHTMLMediaElement.idl
@@ -8,6 +8,8 @@
 #include "nsIDOMMediaError.idl"
 #include "nsIDOMTimeRanges.idl"
 
+interface nsIDOMMediaStream;
+
 /**
  * The nsIDOMHTMLMediaElement interface is an interface to be implemented by the HTML
  * <audio> and <video> elements.
@@ -33,6 +35,7 @@ interface nsIDOMHTMLMediaElement : nsISupports
 
   // network state
            attribute DOMString src;
+           attribute nsIDOMMediaStream mozSrcObject;
   readonly attribute DOMString currentSrc;
   const unsigned short NETWORK_EMPTY = 0;
   const unsigned short NETWORK_IDLE = 1;
@@ -76,6 +79,8 @@ interface nsIDOMHTMLMediaElement : nsISupports
            attribute boolean defaultMuted;
 
   // Mozilla extension: stream capture
+  nsIDOMMediaStream mozCaptureStream();
+  nsIDOMMediaStream mozCaptureStreamUntilEnded();
   readonly attribute boolean mozAudioCaptured;
 
   // Mozilla extension: return embedded metadata from the stream as a
diff --git a/dom/media/bridge/IPeerConnection.idl b/dom/media/bridge/IPeerConnection.idl
index 43858e250e40..fd2c67c4ae3c 100644
--- a/dom/media/bridge/IPeerConnection.idl
+++ b/dom/media/bridge/IPeerConnection.idl
@@ -2,6 +2,7 @@
 #include "nsIDOMWindow.idl"
 #include "nsIPropertyBag2.idl"
 
+interface nsIDOMMediaStream;
 interface nsIDOMDataChannel;
 
 /*
diff --git a/dom/media/moz.build b/dom/media/moz.build
index 340024c534bb..0be6e2960786 100644
--- a/dom/media/moz.build
+++ b/dom/media/moz.build
@@ -17,6 +17,7 @@ if CONFIG['MOZ_WEBRTC']:
     WEBRTC_SIGNALLING_TEST_MANIFESTS += ['tests/mochitest/steeplechase.ini']
 
 XPIDL_SOURCES += [
+    'nsIDOMMediaStream.idl',
     'nsIDOMNavigatorUserMedia.idl',
     'nsIMediaManager.idl',
 ]
diff --git a/dom/media/nsIDOMMediaStream.idl b/dom/media/nsIDOMMediaStream.idl
new file mode 100644
index 000000000000..08a920bd8615
--- /dev/null
+++ b/dom/media/nsIDOMMediaStream.idl
@@ -0,0 +1,27 @@
+/* -*- Mode: IDL; 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/. */
+
+#include "nsISupports.idl"
+
+// undef the GetCurrentTime macro defined in WinBase.h from the MS Platform SDK
+%{C++
+#ifdef GetCurrentTime
+#undef GetCurrentTime
+#endif
+%}
+
+[builtinclass, uuid(3ef760bb-ff19-4dbb-b552-af27ab84b9b8)]
+interface nsIDOMMediaStream : nsISupports
+{
+  /* Placeholder interface only; will be removed after further WebIDL conversion.
+     Do not add anything here. */
+};
+
+[builtinclass, uuid(dd37150a-9823-4605-ac4c-3516629a8aaf)]
+interface nsIDOMLocalMediaStream : nsIDOMMediaStream
+{
+  /* Placeholder interface only; will be removed after further WebIDL conversion.
+     Do not add anything here. */
+};
diff --git a/dom/media/nsIDOMNavigatorUserMedia.idl b/dom/media/nsIDOMNavigatorUserMedia.idl
index 26f60f83b9be..0c2feff270c0 100644
--- a/dom/media/nsIDOMNavigatorUserMedia.idl
+++ b/dom/media/nsIDOMNavigatorUserMedia.idl
@@ -4,6 +4,7 @@
 
 #include "nsISupports.idl"
 #include "nsIVariant.idl"
+#include "nsIDOMMediaStream.idl"
 
 [scriptable, builtinclass, uuid(4af2bdb7-1547-4d10-8886-02a78c3c0b83)]
 interface nsIMediaDevice : nsISupports
@@ -26,7 +27,7 @@ interface nsIDOMGetUserMediaSuccessCallback : nsISupports
 {
   /*
    * value must be a nsIDOMBlob if picture is true and a
-   * DOMLocalMediaStream if either audio or video are true.
+   * nsIDOMLocalMediaStream if either audio or video are true.
    */
   void onSuccess(in nsISupports value);
 };
diff --git a/dom/webidl/MediaStream.webidl b/dom/webidl/MediaStream.webidl
index 698955b161de..1db6b176602e 100644
--- a/dom/webidl/MediaStream.webidl
+++ b/dom/webidl/MediaStream.webidl
@@ -21,7 +21,7 @@ dictionary MediaStreamConstraints {
     DOMString? peerIdentity = null;
 };
 
-interface MediaStream : EventTarget {
+interface MediaStream {
     // readonly attribute DOMString    id;
     sequence<AudioStreamTrack> getAudioTracks();
     sequence<VideoStreamTrack> getVideoTracks();
diff --git a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp
index b2e0f3bf7a7e..c6e7134e40e2 100644
--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp
@@ -703,7 +703,7 @@ PeerConnectionImpl::GetFingerprintHexValue() const
 
 
 nsresult
-PeerConnectionImpl::CreateFakeMediaStream(uint32_t aHint, DOMMediaStream** aRetval)
+PeerConnectionImpl::CreateFakeMediaStream(uint32_t aHint, nsIDOMMediaStream** aRetval)
 {
   MOZ_ASSERT(aRetval);
   PC_AUTO_ENTER_API_CALL(false);
diff --git a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h
index 9628e6c280d0..ff5b8322735d 100644
--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h
@@ -54,6 +54,7 @@ class Fake_MediaStreamTrack;
 #endif
 
 class nsGlobalWindow;
+class nsIDOMMediaStream;
 class nsDOMDataChannel;
 
 namespace mozilla {
@@ -288,7 +289,7 @@ public:
   std::string GetFingerprintHexValue() const;
 
   // Create a fake media stream
-  nsresult CreateFakeMediaStream(uint32_t hint, mozilla::DOMMediaStream** retval);
+  nsresult CreateFakeMediaStream(uint32_t hint, nsIDOMMediaStream** retval);
 
   nsPIDOMWindow* GetWindow() const {
     PC_AUTO_ENTER_API_CALL_NO_CHECK();
diff --git a/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.cpp b/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.cpp
index c527863d0d2e..9e120b51d857 100644
--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.cpp
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.cpp
@@ -295,7 +295,7 @@ nsresult PeerConnectionMedia::Init(const std::vector<NrIceStunServer>& stun_serv
 }
 
 nsresult
-PeerConnectionMedia::AddStream(DOMMediaStream* aMediaStream,
+PeerConnectionMedia::AddStream(nsIDOMMediaStream* aMediaStream,
                                uint32_t hints,
                                uint32_t *stream_id)
 {
@@ -306,6 +306,8 @@ PeerConnectionMedia::AddStream(DOMMediaStream* aMediaStream,
     return NS_ERROR_FAILURE;
   }
 
+  DOMMediaStream* stream = static_cast<DOMMediaStream*>(aMediaStream);
+
   CSFLogDebug(logTag, "%s: MediaStream: %p", __FUNCTION__, aMediaStream);
 
   // Adding tracks here based on nsDOMMediaStream expectation settings
@@ -334,14 +336,14 @@ PeerConnectionMedia::AddStream(DOMMediaStream* aMediaStream,
       CSFLogError(logTag, "Only one stream of any given type allowed");
       return NS_ERROR_FAILURE;
     }
-    if (aMediaStream == lss->GetMediaStream()) {
+    if (stream == lss->GetMediaStream()) {
       localSourceStream = lss;
       *stream_id = u;
       break;
     }
   }
   if (!localSourceStream) {
-    localSourceStream = new LocalSourceStreamInfo(aMediaStream, this);
+    localSourceStream = new LocalSourceStreamInfo(stream, this);
     mLocalSourceStreams.AppendElement(localSourceStream);
     *stream_id = mLocalSourceStreams.Length() - 1;
   }
@@ -357,19 +359,21 @@ PeerConnectionMedia::AddStream(DOMMediaStream* aMediaStream,
 }
 
 nsresult
-PeerConnectionMedia::RemoveStream(DOMMediaStream* aMediaStream,
+PeerConnectionMedia::RemoveStream(nsIDOMMediaStream* aMediaStream,
                                   uint32_t hints,
                                   uint32_t *stream_id)
 {
   MOZ_ASSERT(aMediaStream);
   ASSERT_ON_THREAD(mMainThread);
 
+  DOMMediaStream* stream = static_cast<DOMMediaStream*>(aMediaStream);
+
   CSFLogDebug(logTag, "%s: MediaStream: %p",
     __FUNCTION__, aMediaStream);
 
   for (uint32_t u = 0; u < mLocalSourceStreams.Length(); u++) {
     nsRefPtr<LocalSourceStreamInfo> localSourceStream = mLocalSourceStreams[u];
-    if (localSourceStream->GetMediaStream() == aMediaStream) {
+    if (localSourceStream->GetMediaStream() == stream) {
       *stream_id = u;
 
       if (hints & DOMMediaStream::HINT_CONTENTS_AUDIO) {
diff --git a/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.h b/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.h
index 4ce99b81fd2d..7a2f3f34a2bd 100644
--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.h
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.h
@@ -312,11 +312,11 @@ class PeerConnectionMedia : public sigslot::has_slots<> {
   }
 
   // Add a stream (main thread only)
-  nsresult AddStream(DOMMediaStream* aMediaStream, uint32_t hints,
+  nsresult AddStream(nsIDOMMediaStream* aMediaStream, uint32_t hints,
                      uint32_t *stream_id);
 
   // Remove a stream (main thread only)
-  nsresult RemoveStream(DOMMediaStream* aMediaStream,
+  nsresult RemoveStream(nsIDOMMediaStream* aMediaStream,
                         uint32_t hints,
                         uint32_t *stream_id);
 
diff --git a/media/webrtc/signaling/test/FakeMediaStreams.h b/media/webrtc/signaling/test/FakeMediaStreams.h
index 58a9d88bc6a2..0ce658f4a9ab 100644
--- a/media/webrtc/signaling/test/FakeMediaStreams.h
+++ b/media/webrtc/signaling/test/FakeMediaStreams.h
@@ -22,6 +22,7 @@
 #include "nsTArray.h"
 #include "nsIRunnable.h"
 #include "nsISupportsImpl.h"
+#include "nsIDOMMediaStream.h"
 
 class nsIDOMWindow;
 
@@ -231,7 +232,7 @@ private:
   const bool mIsVideo;
 };
 
-class Fake_DOMMediaStream : public nsISupports
+class Fake_DOMMediaStream : public nsIDOMMediaStream
 {
 protected:
   virtual ~Fake_DOMMediaStream() {
diff --git a/media/webrtc/signaling/test/FakeMediaStreamsImpl.h b/media/webrtc/signaling/test/FakeMediaStreamsImpl.h
index aad2c61eb2c3..3f75f139369e 100644
--- a/media/webrtc/signaling/test/FakeMediaStreamsImpl.h
+++ b/media/webrtc/signaling/test/FakeMediaStreamsImpl.h
@@ -17,7 +17,7 @@ static const int AUDIO_BUFFER_SIZE = 1600;
 static const int NUM_CHANNELS      = 2;
 static const int GRAPH_RATE        = 16000;
 
-NS_IMPL_ISUPPORTS0(Fake_DOMMediaStream)
+NS_IMPL_ISUPPORTS(Fake_DOMMediaStream, nsIDOMMediaStream)
 
 // Fake_MediaStream
 double Fake_MediaStream::StreamTimeToSeconds(mozilla::StreamTime aTime) {
diff --git a/media/webrtc/signaling/test/FakePCObserver.h b/media/webrtc/signaling/test/FakePCObserver.h
index a13922ddeb9b..3e38301a2491 100644
--- a/media/webrtc/signaling/test/FakePCObserver.h
+++ b/media/webrtc/signaling/test/FakePCObserver.h
@@ -18,6 +18,7 @@
 #include "nsTArray.h"
 #include "nsIRunnable.h"
 #include "nsISupportsImpl.h"
+#include "nsIDOMMediaStream.h"
 #include "mozilla/dom/PeerConnectionObserverEnumsBinding.h"
 #include "PeerConnectionImpl.h"
 #include "nsWeakReference.h"
@@ -79,7 +80,7 @@ public:
   virtual NS_IMETHODIMP NotifyDataChannel(nsIDOMDataChannel *channel, ER&) = 0;
   virtual NS_IMETHODIMP OnStateChange(mozilla::dom::PCObserverStateType state_type, ER&,
                                       void* = nullptr) = 0;
-  virtual NS_IMETHODIMP OnAddStream(mozilla::DOMMediaStream *stream, ER&) = 0;
+  virtual NS_IMETHODIMP OnAddStream(nsIDOMMediaStream *stream, ER&) = 0;
   virtual NS_IMETHODIMP OnRemoveStream(ER&) = 0;
   virtual NS_IMETHODIMP OnAddTrack(ER&) = 0;
   virtual NS_IMETHODIMP OnRemoveTrack(ER&) = 0;
diff --git a/media/webrtc/signaling/test/signaling_unittests.cpp b/media/webrtc/signaling/test/signaling_unittests.cpp
index fce87cd166d2..71bf59afbdf5 100644
--- a/media/webrtc/signaling/test/signaling_unittests.cpp
+++ b/media/webrtc/signaling/test/signaling_unittests.cpp
@@ -269,7 +269,7 @@ public:
   NS_IMETHODIMP OnSetRemoteDescriptionError(uint32_t code, const char *msg, ER&);
   NS_IMETHODIMP NotifyDataChannel(nsIDOMDataChannel *channel, ER&);
   NS_IMETHODIMP OnStateChange(PCObserverStateType state_type, ER&, void*);
-  NS_IMETHODIMP OnAddStream(DOMMediaStream *stream, ER&);
+  NS_IMETHODIMP OnAddStream(nsIDOMMediaStream *stream, ER&);
   NS_IMETHODIMP OnRemoveStream(ER&);
   NS_IMETHODIMP OnAddTrack(ER&);
   NS_IMETHODIMP OnRemoveTrack(ER&);
@@ -429,21 +429,23 @@ TestObserver::OnStateChange(PCObserverStateType state_type, ER&, void*)
 
 
 NS_IMETHODIMP
-TestObserver::OnAddStream(DOMMediaStream *stream, ER&)
+TestObserver::OnAddStream(nsIDOMMediaStream *stream, ER&)
 {
   PR_ASSERT(stream);
 
-  std::cout << name << ": OnAddStream called hints=" << stream->GetHintContents()
+  DOMMediaStream *ms = static_cast<DOMMediaStream *>(stream);
+
+  std::cout << name << ": OnAddStream called hints=" << ms->GetHintContents()
             << " thread=" << PR_GetCurrentThread() << std::endl ;
 
   onAddStreamCalled = true;
 
-  streams.push_back(stream);
+  streams.push_back(ms);
 
   // We know that the media stream is secretly a Fake_SourceMediaStream,
   // so now we can start it pulling from us
   nsRefPtr<Fake_SourceMediaStream> fs =
-    static_cast<Fake_SourceMediaStream *>(stream->GetStream());
+    static_cast<Fake_SourceMediaStream *>(ms->GetStream());
 
   test_utils->sts_target()->Dispatch(
     WrapRunnable(fs, &Fake_SourceMediaStream::Start),
diff --git a/xpcom/reflect/xptinfo/ShimInterfaceInfo.cpp b/xpcom/reflect/xptinfo/ShimInterfaceInfo.cpp
index 226d4a5ec102..b18e46e2985f 100644
--- a/xpcom/reflect/xptinfo/ShimInterfaceInfo.cpp
+++ b/xpcom/reflect/xptinfo/ShimInterfaceInfo.cpp
@@ -102,6 +102,7 @@
 #include "nsIDOMKeyEvent.h"
 #include "nsIDOMMediaError.h"
 #include "nsIDOMMediaList.h"
+#include "nsIDOMMediaStream.h"
 #include "nsIDOMMessageEvent.h"
 #include "nsIDOMMouseEvent.h"
 #include "nsIDOMMouseScrollEvent.h"
@@ -235,8 +236,10 @@
 #include "mozilla/dom/HTMLTitleElementBinding.h"
 #include "mozilla/dom/HTMLUListElementBinding.h"
 #include "mozilla/dom/KeyEventBinding.h"
+#include "mozilla/dom/LocalMediaStreamBinding.h"
 #include "mozilla/dom/MediaErrorBinding.h"
 #include "mozilla/dom/MediaListBinding.h"
+#include "mozilla/dom/MediaStreamBinding.h"
 #include "mozilla/dom/MessageEventBinding.h"
 #include "mozilla/dom/MouseEventBinding.h"
 #include "mozilla/dom/MouseScrollEventBinding.h"
@@ -422,8 +425,10 @@ const ComponentsInterfaceShimEntry kComponentsInterfaceShimMap[] =
   DEFINE_SHIM(HTMLTitleElement),
   DEFINE_SHIM(HTMLUListElement),
   DEFINE_SHIM(KeyEvent),
+  DEFINE_SHIM(LocalMediaStream),
   DEFINE_SHIM(MediaError),
   DEFINE_SHIM(MediaList),
+  DEFINE_SHIM(MediaStream),
   DEFINE_SHIM(MessageEvent),
   DEFINE_SHIM(MouseEvent),
   DEFINE_SHIM(MouseScrollEvent),