Request frame for new sinks from MediaStreamVideoTrack

content/renderer/media/media_stream_video_track.cc

Index: content/renderer/media/media_stream_video_track.cc
diff --git a/content/renderer/media/media_stream_video_track.cc b/content/renderer/media/media_stream_video_track.cc
index cae744bafd0e7ed377a24b6a4282f361b1e4ac68..68212c248d8c1658b7f334cf102204f25ea6bc4c 100644
--- a/content/renderer/media/media_stream_video_track.cc
+++ b/content/renderer/media/media_stream_video_track.cc
@@ -247,6 +247,9 @@ void MediaStreamVideoTrack::AddSink(
   DCHECK(std::find(sinks_.begin(), sinks_.end(), sink) == sinks_.end());
   sinks_.push_back(sink);
   frame_deliverer_->AddCallback(sink, callback);
+  // Request source to deliver a new frame because a new sink is added.
+  if (source_)
+    source_->RequestFrame();
 }
 
 void MediaStreamVideoTrack::RemoveSink(MediaStreamVideoSink* sink) {