Bug 909187: Part 1-Refactor MediaStreamTrack disabling so we can call it directly and access from other threads r=roc (reland)

content/media/MediaSegment.h

@@ -100,6 +100,10 @@ public:
    * Insert aDuration of null data at the end of the segment.
    */
   virtual void AppendNullData(TrackTicks aDuration) = 0;
+  /**
+   * Replace contents with disabled data of the same duration
+   */
+  virtual void ReplaceWithDisabled() = 0;
   /**
    * Remove all contents, setting duration to 0.
    */
@@ -190,6 +194,15 @@ public:
     }
     mDuration += aDuration;
   }
+  virtual void ReplaceWithDisabled()
+  {
+    if (GetType() != AUDIO) {
+      MOZ_CRASH("Disabling unknown segment type");
+    }
+    TrackTicks duration = GetDuration();
+    Clear();
+    AppendNullData(duration);
+  }
   virtual void Clear()
   {
     mDuration = 0;

content/media/MediaStreamGraph.cpp

@@ -1912,29 +1912,15 @@ MediaStream::SetTrackEnabled(TrackID aTrackID, bool aEnabled)
 }
 
 void
-MediaStream::ApplyTrackDisabling(TrackID aTrackID, MediaSegment* aSegment)
+MediaStream::ApplyTrackDisabling(TrackID aTrackID, MediaSegment* aSegment, MediaSegment* aRawSegment)
 {
+  // mMutex must be owned here if this is a SourceMediaStream
   if (!mDisabledTrackIDs.Contains(aTrackID)) {
     return;
   }
-
-  switch (aSegment->GetType()) {
-  case MediaSegment::AUDIO: {
-    TrackTicks duration = aSegment->GetDuration();
-    aSegment->Clear();
-    aSegment->AppendNullData(duration);
-    break;
-  }
-  case MediaSegment::VIDEO: {
-    for (VideoSegment::ChunkIterator i(*static_cast<VideoSegment*>(aSegment));
-         !i.IsEnded(); i.Next()) {
-      VideoChunk& chunk = *i;
-      chunk.SetForceBlack(true);
-    }
-    break;
-  }
-  default:
-    MOZ_CRASH("Unknown track type");
+  aSegment->ReplaceWithDisabled();
+  if (aRawSegment) {
+    aRawSegment->ReplaceWithDisabled();
   }
 }
 
@@ -1990,6 +1976,10 @@ SourceMediaStream::AppendToTrack(TrackID aID, MediaSegment* aSegment, MediaSegme
       // Indirect listeners (via subsequent TrackUnion nodes) are synced to
       // playout time, and so can be delayed by buffering.
 
+      // Apply track disabling before notifying any consumers directly
+      // or inserting into the graph
+      ApplyTrackDisabling(aID, aSegment, aRawSegment);
+
       // Must notify first, since AppendFrom() will empty out aSegment
       NotifyDirectConsumers(track, aRawSegment ? aRawSegment : aSegment);
       track->mData->AppendFrom(aSegment); // note: aSegment is now dead

content/media/MediaStreamGraph.h

@@ -459,7 +459,7 @@ public:
 
   StreamBuffer::Track* EnsureTrack(TrackID aTrack, TrackRate aSampleRate);
 
-  void ApplyTrackDisabling(TrackID aTrackID, MediaSegment* aSegment);
+  void ApplyTrackDisabling(TrackID aTrackID, MediaSegment* aSegment, MediaSegment* aRawSegment = nullptr);
 
   DOMMediaStream* GetWrapper()
   {
@@ -679,6 +679,11 @@ public:
       FinishWithLockHeld();
     }
 
+  // Overriding allows us to hold the mMutex lock while changing the track enable status
+  void SetTrackEnabledImpl(TrackID aTrackID, bool aEnabled) {
+    MutexAutoLock lock(mMutex);
+    MediaStream::SetTrackEnabledImpl(aTrackID, aEnabled);
+  }
 
   /**
    * End all tracks and Finish() this stream.  Used to voluntarily revoke access

content/media/VideoSegment.h

@@ -107,6 +107,14 @@ public:
     }
     return &c->mFrame;
   }
+  // Override default impl
+  virtual void ReplaceWithDisabled() MOZ_OVERRIDE {
+    for (ChunkIterator i(*this);
+         !i.IsEnded(); i.Next()) {
+      VideoChunk& chunk = *i;
+      chunk.SetForceBlack(true);
+    }
+  }
 
   // Segment-generic methods not in MediaSegmentBase
   static Type StaticType() { return VIDEO; }