New class AdaptedVideoTrackSource.

webrtc/media/base/videosourceinterface.h

Index: webrtc/media/base/videosourceinterface.h
diff --git a/webrtc/media/base/videosourceinterface.h b/webrtc/media/base/videosourceinterface.h
index bae02c8d0fc3c453d199aa7853b08ecde299e136..efcc0bfff76702cc6c3b7c3f75a03ce5647bbe3a 100644
--- a/webrtc/media/base/videosourceinterface.h
+++ b/webrtc/media/base/videosourceinterface.h
@@ -18,9 +18,13 @@ namespace rtc {
 
 // VideoSinkWants is used for notifying the source of properties a video frame
 // should have when it is delivered to a certain sink.
+
 struct VideoSinkWants {
-  // Tells the source whether the sink wants frames with rotation applied.
-  // By default, any rotation must be applied by the sink.
+  // Tells the source whether the sink wants frames with rotation applied. By
+  // default, any rotation must be applied by the sink. The VideoBroadcaster

[perkj_webrtc, 2016/09/21 08:59:23]

I don't think think the comment about VideoBroadCaster belongs in the interface.
That is an implementation detail.

[nisse-webrtc, 2016/09/21 09:43:59]

The intention is to explain what the rotation_applied flag means. Which I think
belongs here.

Now, the meaning currently is a bit muddy. I think the alternative is to clarify
that even if it is set, the sink might get frames with pending rotation. (And
then it becomes an implementation detail of VideoBroadcaster that it's more
strict, to help current sinks which need that).

What do you suggest, re-phrasing, moving to where?

+  // class ensures that if a sink sets rotation_applied == true, it will never
+  // receive a frame with pending rotation. Unclear if we want to provide that
+  // guarantee in general.
   bool rotation_applied = false;
 
   // Tells the source that the sink only wants black frames.