Media Remoting: Switch to remoting only when media is playing.

media/base/media_observer.h

Index: media/base/media_observer.h
diff --git a/media/base/media_observer.h b/media/base/media_observer.h
index ce81e3bb15ca4bd799edc60ff960340f04eb199d..31357810f1c03ca5cb02e6fa104aa5b768820811 100644
--- a/media/base/media_observer.h
+++ b/media/base/media_observer.h
@@ -36,6 +36,10 @@ class MEDIA_EXPORT MediaObserver {
   // "disableRemotePlayback" media element attribute, as described in the
   // Remote Playback API spec: https://w3c.github.io/remote-playback
   virtual void OnRemotePlaybackDisabled(bool disabled) = 0;
+
+  // Called when the media is playing/paused.
+  virtual void OnPlaying() = 0;
+  virtual void OnPaused() = 0;
 };
 
 }  // namespace media