getUserMedia: handle the device starting status report.

content/renderer/media/video_capture_impl.h

Index: content/renderer/media/video_capture_impl.h
diff --git a/content/renderer/media/video_capture_impl.h b/content/renderer/media/video_capture_impl.h
index 55e8b536d559be4fcecca924c434f8b2c37181f1..d2d92139d2f62647ea42aaa04ddd19d54a97ebcf 100644
--- a/content/renderer/media/video_capture_impl.h
+++ b/content/renderer/media/video_capture_impl.h
@@ -151,6 +151,12 @@ class CONTENT_EXPORT VideoCaptureImpl : public mojom::VideoCaptureObserver {
 
   base::ThreadChecker io_thread_checker_;
 
+  // Flag set to True when captured frames are dropped due to arriving earlier
+  // than OnStarted event. Then a frame refresh request will be sent out later
+  // when OnStarted arrives, for a new frame to start the video call with.
+  // This only has effect on screen capture.
+  bool maybe_refresh_frame_;

[chfremer, 2017/03/02 17:56:10]

The "maybe_" prefix seems redundant, since it is clear that the bool may be true
or false. I recommend naming this "should_request_refresh_frame_on_started_".

The comment "This only has effect on screen capture." is a dangerous claim to
make here, because it assumes knowledge of what happens outside of this class. I
understand that you want to document the effect on the larger context, but this
is not a good location for putting this information, because when the larger
context changes, who will know that there is documentation hiding in here that
needs to be updated?

[braveyao, 2017/03/03 17:53:12]

Done.

+
   // WeakPtrFactory pointing back to |this| object, for use with
   // media::VideoFrames constructed in OnBufferReceived() from buffers cached
   // in |client_buffers_|.