[Cast] Repurpose CastInitializationStatus for variable frame size support.

media/cast/cast_sender.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // This is the main interface for the cast sender.
 //
 // The AudioFrameInput, VideoFrameInput and PacketReciever interfaces should
 // be accessed from the main thread.
 
 #ifndef MEDIA_CAST_CAST_SENDER_H_
@@ skipping 69 matching lines @@
 
   virtual ~CastSender() {}
 
   // All video frames for the session should be inserted to this object.
   virtual scoped_refptr<VideoFrameInput> video_frame_input() = 0;
 
   // All audio frames for the session should be inserted to this object.
   virtual scoped_refptr<AudioFrameInput> audio_frame_input() = 0;
 
   // Initialize the audio stack. Must be called in order to send audio frames.
-  // Status of the initialization will be returned on cast_initialization_cb.
+  // |status_change_cb| will be run as operational status changes.
   virtual void InitializeAudio(
       const AudioSenderConfig& audio_config,
-      const CastInitializationCallback& cast_initialization_cb) = 0;
+      const StatusChangeCallback& status_change_cb) = 0;
 
   // Initialize the video stack. Must be called in order to send video frames.
-  // Status of the initialization will be returned on cast_initialization_cb.
+  // |status_change_cb| will be run as operational status changes.
+  //
+  // TODO(miu): Remove the VEA-specific callbacks.  http://crbug.com/454029
   virtual void InitializeVideo(
       const VideoSenderConfig& video_config,
-      const CastInitializationCallback& cast_initialization_cb,
+      const StatusChangeCallback& status_change_cb,
       const CreateVideoEncodeAcceleratorCallback& create_vea_cb,
       const CreateVideoEncodeMemoryCallback& create_video_encode_mem_cb) = 0;
 
   // Change the target delay. This is only valid if the receiver
   // supports the "adaptive_target_delay" rtp extension.
   virtual void SetTargetPlayoutDelay(
       base::TimeDelta new_target_playout_delay) = 0;
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_CAST_SENDER_H_