Enable audio/video tag in content_shell

content/browser/renderer_host/media/audio_renderer_host.h

Index: content/browser/renderer_host/media/audio_renderer_host.h
diff --git a/content/browser/renderer_host/media/audio_renderer_host.h b/content/browser/renderer_host/media/audio_renderer_host.h
index 16e2d02120c78840612ffbb016f9a20f4c707618..513fc0d88f46734fb22e0cfb3b438e116a708ebe 100644
--- a/content/browser/renderer_host/media/audio_renderer_host.h
+++ b/content/browser/renderer_host/media/audio_renderer_host.h
@@ -209,6 +209,12 @@ class CONTENT_EXPORT AudioRendererHost
   // event is received.
   AudioEntry* LookupByController(media::AudioOutputController* controller);
 
+  // Notifies |media_observer_| about various audio stream events.
+  void OnSetAudioStreamPlaying(int stream_id, bool playing);
+  void OnSetAudioStreamStatus(int stream_id, const std::string& status);
+  void OnSetAudioStreamVolume(int stream_id, double volume);
+  void OnDeleteAudioStream(int stream_id);
+
   // Return resource_context_->media_observer() or a cached copy thereof.
   // This is necessary because resource_context_ can be destructed before all
   // AudioEntries have been deleted. The MediaObserver's lifetime is tied to