getUserMeida: report device starting states

content/browser/renderer_host/media/video_capture_controller_event_handler.h

Index: content/browser/renderer_host/media/video_capture_controller_event_handler.h
diff --git a/content/browser/renderer_host/media/video_capture_controller_event_handler.h b/content/browser/renderer_host/media/video_capture_controller_event_handler.h
index 301070cceaeddfb458131c7edae4349f59f45ba2..d90c3093d4bf896c764e41a8b2e19fb13e321b2a 100644
--- a/content/browser/renderer_host/media/video_capture_controller_event_handler.h
+++ b/content/browser/renderer_host/media/video_capture_controller_event_handler.h
@@ -24,6 +24,11 @@ typedef int VideoCaptureControllerID;
 // VideoCaptureControllerEventHandler is the interface for
 // VideoCaptureController to notify clients about the events such as
 // BufferReady, FrameInfo, Error, etc.
+
+// OnError and OnEnded need to be scheduled to the end of message queue to
+// guarantee some other clearing jobs are done before they are handled.
+// Other methods can be forwarded synchronously.
+
 // TODO(mcasas): https://crbug.com/654176 merge back into VideoCaptureController
 class CONTENT_EXPORT VideoCaptureControllerEventHandler {
  public:
@@ -49,6 +54,9 @@ class CONTENT_EXPORT VideoCaptureControllerEventHandler {
   // The capture session has ended and no more frames will be sent.
   virtual void OnEnded(VideoCaptureControllerID id) = 0;
 
+  // VideoCaptureDevice has successfully started the device.
+  virtual void OnStarted(VideoCaptureControllerID id) = 0;
+
  protected:
   virtual ~VideoCaptureControllerEventHandler() {}
 };