Allow muting/unmuting audio through media track API

media/filters/media_source_state.h

Index: media/filters/media_source_state.h
diff --git a/media/filters/media_source_state.h b/media/filters/media_source_state.h
index e6878f6071ce9efe5ac11232970f01395d60a43a..0619b1157254f7005b883051bd99ac9f7df9d8fd 100644
--- a/media/filters/media_source_state.h
+++ b/media/filters/media_source_state.h
@@ -20,12 +20,13 @@ using base::TimeDelta;
 
 class ChunkDemuxerStream;
 class FrameProcessor;
+class MediaTrack;
 
 // Contains state belonging to a source id.
 class MEDIA_EXPORT MediaSourceState {
  public:
   // Callback signature used to create ChunkDemuxerStreams.
-  typedef base::Callback<ChunkDemuxerStream*(DemuxerStream::Type)>
+  typedef base::Callback<ChunkDemuxerStream*(const MediaTrack&)>
       CreateDemuxerStreamCB;
 
   typedef base::Callback<void(ChunkDemuxerStream*, const TextTrackConfig&)>