Detect AudioInputStream muting and propagate to MediaStreamAudioSource.

media/audio/audio_input_ipc.h

Index: media/audio/audio_input_ipc.h
diff --git a/media/audio/audio_input_ipc.h b/media/audio/audio_input_ipc.h
index e69f33d4c8584cd129e91808b5e5d0a0ddd06be9..058d4d0990d46ce78df6402b8d27a49382be83dc 100644
--- a/media/audio/audio_input_ipc.h
+++ b/media/audio/audio_input_ipc.h
@@ -35,6 +35,9 @@ class MEDIA_EXPORT AudioInputIPCDelegate {
   // Called when state of an audio stream has changed.
   virtual void OnError() = 0;
 
+  // Called when an audio stream is muted or unmuted.
+  virtual void OnMuted(bool is_muted) = 0;
+
   // Called when the AudioInputIPC object is going away and/or when the
   // IPC channel has been closed and no more IPC requests can be made.
   // Implementations should delete their owned AudioInputIPC instance