New class AdaptedVideoTrackSource.

webrtc/media/base/videobroadcaster.h

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 27 matching lines @@
                        const VideoSinkWants& wants) override;
   void RemoveSink(VideoSinkInterface<cricket::VideoFrame>* sink) override;
 
   // Returns true if the next frame will be delivered to at least one sink.
   bool frame_wanted() const;
 
   // Returns VideoSinkWants a source is requested to fulfill. They are
   // aggregated by all VideoSinkWants from all sinks.
   VideoSinkWants wants() const;
 
+  // This method ensures that if a sink sets rotation_applied == true,
+  // it will never receive a frame with pending rotation. Our caller
+  // may pass in frames without precise synchronization with changes
+  // to the VideoSinkWants.
   void OnFrame(const cricket::VideoFrame& frame) override;
 
  protected:
   void UpdateWants() EXCLUSIVE_LOCKS_REQUIRED(sinks_and_wants_lock_);
   const rtc::scoped_refptr<webrtc::VideoFrameBuffer>& GetBlackFrameBuffer(
       int width, int height)
       EXCLUSIVE_LOCKS_REQUIRED(sinks_and_wants_lock_);
 
   ThreadChecker thread_checker_;
   rtc::CriticalSection sinks_and_wants_lock_;
 
   VideoSinkWants current_wants_ GUARDED_BY(sinks_and_wants_lock_);
   rtc::scoped_refptr<webrtc::VideoFrameBuffer> black_frame_buffer_;
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_MEDIA_BASE_VIDEOBROADCASTER_H_