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

webrtc/video/video_receive_stream.h

Index: webrtc/video/video_receive_stream.h
diff --git a/webrtc/video/video_receive_stream.h b/webrtc/video/video_receive_stream.h
index 3f6d55a0da8b2d9dcc6bfc955b9ab6b7ca1bac19..d37aece98cc910ff6b1ee54a371fabe7855d5eed 100644
--- a/webrtc/video/video_receive_stream.h
+++ b/webrtc/video/video_receive_stream.h
@@ -96,10 +96,10 @@ class VideoReceiveStream : public webrtc::VideoReceiveStream,
   CallStats* const call_stats_;
 
   vcm::VideoReceiver video_receiver_;
-  IncomingVideoStream incoming_video_stream_;
+  std::unique_ptr<rtc::VideoSinkInterface<VideoFrame>> incoming_video_stream_;

[nisse-webrtc, 2016/06/20 13:47:55]

I think ownership here is a bit unfortunate. The grand plan is to move ownership
to whoever creates the webrtc::VideoReceivStream::Config (which uses an un-owned
VideoSinkInterface pointer)?

Then I think it makes sense to change this back to an IncomingVideoStream
pointer, and think about it not as the a pointer to the sink to use, but a
pointer to an object we own and have to clean up. And let the destructor of the
abstract VideoSinkInterface stay non-public.

[tommi, 2016/06/20 14:24:51]

Yes (or something along those lines)
I think making the dtor of VideoSinkInterface public, is still a good thing and
required for the above grand plan.  There's no refcounting going on, so the
public dtor should be fine.

The interface that's needed here, is a VideoSinkInterface, and not specifically
IncomingVideoStream.  We only need to call the ctor of IncomingVideoStream and
once we've got that, we don't need more.  This also makes the class' header
dependencies one class less and the same as for the decoder (in all cases, not
just with smoothing enabled).

[nisse-webrtc, 2016/06/20 14:51:39]

Acknowledged.

When we introduced this interface some months ago after extensive design
discussions, we might have thought that it would be used by refcounted objects.
If that's not the case, a public constructor makes a lot more sense.

   ReceiveStatisticsProxy stats_proxy_;
   RtpStreamReceiver rtp_stream_receiver_;
-  VideoStreamDecoder video_stream_decoder_;
+  std::unique_ptr<VideoStreamDecoder> video_stream_decoder_;
   ViESyncModule vie_sync_;
 
   std::unique_ptr<IvfFileWriter> ivf_writer_;