Implement disabling and enabling media tracks

media/blink/webmediaplayer_impl.h

Index: media/blink/webmediaplayer_impl.h
diff --git a/media/blink/webmediaplayer_impl.h b/media/blink/webmediaplayer_impl.h
index 1943c5de84cf7037e75445e40cb086e63fc67595..eb8b13c35ca3afb324d3125868a9c0be2219ddfd 100644
--- a/media/blink/webmediaplayer_impl.h
+++ b/media/blink/webmediaplayer_impl.h
@@ -67,6 +67,7 @@ class GLES2Interface;
 namespace media {
 class AudioHardwareConfig;
 class ChunkDemuxer;
+class DemuxerStream;
 class GpuVideoAcceleratorFactories;
 class MediaLog;
 class UrlIndex;
@@ -281,6 +282,10 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
   // Gets the duration value reported by the pipeline.
   double GetPipelineDuration() const;
 
+  // Restarts playback of the given demuxer |stream| at the position |time|
+  // after it has been re-enabled.
+  void RestartStreamPlayback(DemuxerStream* stream, base::TimeDelta time);
+
   // Called by VideoRendererImpl on its internal thread with the new frame to be
   // painted.
   void FrameReady(const scoped_refptr<VideoFrame>& frame);