getUserMeida: report device starting states

content/browser/renderer_host/media/video_capture_controller_event_handler.h

 // Copyright (c) 2012 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_EVENT_HANDLER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_EVENT_HANDLER_H_
 
 #include <memory>
 
 #include "base/memory/shared_memory.h"
@@ skipping 29 matching lines @@
                                  int buffer_id) = 0;
 
   // A buffer has been filled with a captured VideoFrame.
   virtual void OnBufferReady(VideoCaptureControllerID id,
                              int buffer_id,
                              const scoped_refptr<media::VideoFrame>& frame) = 0;
 
   // The capture session has ended and no more frames will be sent.
   virtual void OnEnded(VideoCaptureControllerID id) = 0;
 
+  // VideoCaptureDevice has successfully started the device.
+  // OnStarted can be forwarded directly, while OnError&OnEnded need to be
+  // scheduled to the end of message queue to guarantee some other clearing
+  // jobs are done before they are handled.
+  virtual void OnStarted(VideoCaptureControllerID id) = 0;

[chfremer, 2017/02/17 23:51:14]

The second sentence of the comment for this method concerns several other
methods. It would probably not be found by a reader only looking at OnError or
OnEnded. Therefore it should go to the class description. Could you please move
it to there?

[braveyao, 2017/02/22 18:06:44]

Done.

+
  protected:
   virtual ~VideoCaptureControllerEventHandler() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_EVENT_HANDLER_H_