Bug 1208328 - Implement MediaStream.onaddtrack. r=jib, r=smaug

MozReview-Commit-ID: JVZO5mlxvgW

--HG--
extra : rebase_source : b2ec734dc408e96c9a9f265c11c7308895c3b6ce

dom/media/DOMMediaStream.cpp

@@ -10,6 +10,7 @@
 #include "nsIUUIDGenerator.h"
 #include "nsPIDOMWindow.h"
 #include "mozilla/dom/MediaStreamBinding.h"
+#include "mozilla/dom/MediaStreamTrackEvent.h"
 #include "mozilla/dom/LocalMediaStreamBinding.h"
 #include "mozilla/dom/AudioNode.h"
 #include "AudioChannelAgent.h"
@@ -1002,6 +1003,9 @@ DOMMediaStream::CreateDOMTrack(TrackID aTrackID, MediaSegment::Type aType,
     new TrackPort(mPlaybackPort, track, TrackPort::InputPortOwnership::EXTERNAL));
 
   NotifyTrackAdded(track);
+
+  DispatchTrackEvent(NS_LITERAL_STRING("addtrack"), track);
+
   return track;
 }
 
@@ -1241,6 +1245,22 @@ DOMMediaStream::NotifyTrackRemoved(const RefPtr<MediaStreamTrack>& aTrack)
   // track has been confirmed removed by the graph. See BlockPlaybackTrack().
 }
 
+nsresult
+DOMMediaStream::DispatchTrackEvent(const nsAString& aName,
+                                   const RefPtr<MediaStreamTrack>& aTrack)
+{
+  MOZ_ASSERT(aName == NS_LITERAL_STRING("addtrack"),
+             "Only 'addtrack' is supported at this time");
+
+  MediaStreamTrackEventInit init;
+  init.mTrack = aTrack;
+
+  RefPtr<MediaStreamTrackEvent> event =
+    MediaStreamTrackEvent::Constructor(this, aName, init);
+
+  return DispatchTrustedEvent(event);
+}
+
 void
 DOMMediaStream::CreateAndAddPlaybackStreamListener(MediaStream* aStream)
 {

dom/media/DOMMediaStream.h

@@ -362,6 +362,8 @@ public:
   /** Identical to CloneInternal(TrackForwardingOption::EXPLICIT) */
   already_AddRefed<DOMMediaStream> Clone();
 
+  IMPL_EVENT_HANDLER(addtrack)
+
   // NON-WebIDL
 
   /**
@@ -522,7 +524,12 @@ public:
    * Called for each track in our owned stream to indicate to JS that we
    * are carrying that track.
    *
-   * Creates a MediaStreamTrack, adds it to mTracks and returns it.
+   * Creates a MediaStreamTrack, adds it to mTracks, raises "addtrack" and
+   * returns it.
+   *
+   * Note that "addtrack" is raised synchronously and only has an effect if
+   * this MediaStream is already exposed to script. For spec compliance this is
+   * to be called from an async task.
    */
   MediaStreamTrack* CreateDOMTrack(TrackID aTrackID, MediaSegment::Type aType,
                                    MediaStreamTrackSource* aSource);
@@ -603,6 +610,10 @@ protected:
   // Dispatches NotifyTrackRemoved() to all registered track listeners.
   void NotifyTrackRemoved(const RefPtr<MediaStreamTrack>& aTrack);
 
+  // Dispatches "addtrack" or "removetrack".
+  nsresult DispatchTrackEvent(const nsAString& aName,
+                              const RefPtr<MediaStreamTrack>& aTrack);
+
   class OwnedStreamListener;
   friend class OwnedStreamListener;
 

dom/webidl/MediaStream.webidl

@@ -43,7 +43,7 @@ interface MediaStream : EventTarget {
     // readonly    attribute boolean      active;
     //             attribute EventHandler onactive;
     //             attribute EventHandler oninactive;
-    //             attribute EventHandler onaddtrack;
+                attribute EventHandler onaddtrack;
     //             attribute EventHandler onremovetrack;
     readonly attribute double currentTime;
 };

dom/webidl/MediaStreamTrackEvent.webidl

@@ -8,15 +8,12 @@
  */
 
 dictionary MediaStreamTrackEventInit : EventInit {
-  MediaStreamTrack? track = null;
-  RTCRtpReceiver? receiver = null;
-  MediaStream? stream = null;
+    required MediaStreamTrack track;
 };
 
-[Pref="media.peerconnection.enabled",
- Constructor(DOMString type, optional MediaStreamTrackEventInit eventInitDict)]
+[Exposed=Window,
+ Constructor (DOMString type, MediaStreamTrackEventInit eventInitDict)]
 interface MediaStreamTrackEvent : Event {
-  readonly attribute RTCRtpReceiver? receiver;
-  readonly attribute MediaStreamTrack? track;
-  readonly attribute MediaStream? stream;
+    [SameObject]
+    readonly        attribute MediaStreamTrack track;
 };