Bug 1170958 - Add input stream and track as args to NotifyQueuedTrackChanges. r=roc

This allows for tracking the input track of an added track (for
ProcessedMediaStream tracks; SourceMediaStream tracks don't have input
tracks) directly in the NotifyQueuedTrackChanges handler, which will be
necessary for locking MediaInputPorts to specific tracks.

dom/html/HTMLMediaElement.cpp

@@ -3053,7 +3053,9 @@ public:
   virtual void NotifyQueuedTrackChanges(MediaStreamGraph* aGraph, TrackID aID,
                                         StreamTime aTrackOffset,
                                         uint32_t aTrackEvents,
-                                        const MediaSegment& aQueuedMedia) override
+                                        const MediaSegment& aQueuedMedia,
+                                        MediaStream* aInputStream,
+                                        TrackID aInputTrackID) override
   {
     MutexAutoLock lock(mMutex);
     if (mInitialSize != gfx::IntSize(0,0) ||