Reland of Split IncomingVideoStream into two implementations, with smoothing and without.

webrtc/media/base/videosinkinterface.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.
  */
 
 #ifndef WEBRTC_MEDIA_BASE_VIDEOSINKINTERFACE_H_
 #define WEBRTC_MEDIA_BASE_VIDEOSINKINTERFACE_H_
 
 // TODO(nisse): Consider moving this interface (and possibly
 // VideoSourceInterface too) from media/base to common_video, to
 // reduce dependency cycles.
 namespace rtc {
 
 template <typename VideoFrameT>
 class VideoSinkInterface {
  public:
+  virtual ~VideoSinkInterface() {}
+
   virtual void OnFrame(const VideoFrameT& frame) = 0;
- protected:
-  virtual ~VideoSinkInterface() {}
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_MEDIA_BASE_VIDEOSINKINTERFACE_H_