Implement disabling and enabling media tracks

media/base/renderer.h

Index: media/base/renderer.h
diff --git a/media/base/renderer.h b/media/base/renderer.h
index fae6115f3c8ee619eb1efa3da7c4195b40244cd3..e3f73f639608b77065dea356d43848769c08bf9d 100644
--- a/media/base/renderer.h
+++ b/media/base/renderer.h
@@ -16,6 +16,7 @@
 
 namespace media {
 
+class DemuxerStream;
 class DemuxerStreamProvider;
 class RendererClient;
 class VideoFrame;
@@ -49,6 +50,9 @@ class MEDIA_EXPORT Renderer {
   // Starts rendering from |time|.
   virtual void StartPlayingFrom(base::TimeDelta time) = 0;
 
+  virtual void RestartStreamPlayback(DemuxerStream* stream,
+                                     base::TimeDelta time) = 0;
+
   // Updates the current playback rate. The default playback rate should be 1.
   virtual void SetPlaybackRate(double playback_rate) = 0;