[Cast] Repurpose CastInitializationStatus for variable frame size support.

media/cast/sender/audio_sender.h

Index: media/cast/sender/audio_sender.h
diff --git a/media/cast/sender/audio_sender.h b/media/cast/sender/audio_sender.h
index d7f8c69432d4f908f71efae5891be1a20f95e313..6148d0e91d1a5e48a2e24f7bd5ba7082807809b1 100644
--- a/media/cast/sender/audio_sender.h
+++ b/media/cast/sender/audio_sender.h
@@ -33,20 +33,14 @@ class AudioSender : public FrameSender,
  public:
   AudioSender(scoped_refptr<CastEnvironment> cast_environment,
               const AudioSenderConfig& audio_config,
+              const StatusChangeCallback& status_change_cb,
               CastTransportSender* const transport_sender);
 
   ~AudioSender() override;
 
-  CastInitializationStatus InitializationResult() const {
-    return cast_initialization_status_;
-  }
-
   // Note: It is not guaranteed that |audio_frame| will actually be encoded and
   // sent, if AudioSender detects too many frames in flight.  Therefore, clients
   // should be careful about the rate at which this method is called.
-  //
-  // Note: It is invalid to call this method if InitializationResult() returns
-  // anything but STATUS_AUDIO_INITIALIZED.
   void InsertAudio(scoped_ptr<AudioBus> audio_bus,
                    const base::TimeTicks& recorded_time);