Make cricket::VideoCapturer implement VideoSourceInterface

talk/media/base/capturerenderadapter.h

Index: talk/media/base/capturerenderadapter.h
diff --git a/talk/media/base/capturerenderadapter.h b/talk/media/base/capturerenderadapter.h
index f972c983c5d85b3862ad1e7dd82e6cc01b56a048..ed74294e2af1cf188e58488c814ee651b58fb718 100644
--- a/talk/media/base/capturerenderadapter.h
+++ b/talk/media/base/capturerenderadapter.h
@@ -38,7 +38,6 @@
 
 #include "talk/media/base/videocapturer.h"
 #include "webrtc/base/criticalsection.h"
-#include "webrtc/base/sigslot.h"
 #include "webrtc/media/base/videosinkinterface.h"
 
 namespace cricket {
@@ -46,7 +45,7 @@ namespace cricket {
 class VideoCapturer;
 class VideoProcessor;
 
-class CaptureRenderAdapter : public sigslot::has_slots<> {
+class CaptureRenderAdapter : public rtc::VideoSinkInterface<VideoFrame> {

[nisse-webrtc, 2016/02/03 09:16:34]

After these changes, it looks like this class is 

1. Functionally equivalent to a VideoTrack without the muting logic. I.e, a
plain mux.

2. Redundant, any code calling AddSink on this object could just as well call
AddSink directly on the VideoCapturer.

Correct?

[pthatcher1, 2016/02/03 15:38:35]

I'd like it if we can just remove this class altogether.   It's only used in one
place:  VideoCapturerState, which only uses it for 2 things:

1.  To help implement CaptureManager::AddVideoSink and
CaptureManager::RemoveVideoSink
2.  To store a video capturer to be used in
CaptureManager::UnregisterVideoCapturer.

For #1, it could probably use our VideoMux (whatever we end up calling it)
instead of CaptureRendererAdapter.  Our we could go one step further: 
CaptureManager::AddVideoSink and CaptureManager::RemoveVideoSink are only used
to implement VideoSource::AddSink and VideoSource::RemoveSink, so maybe we could
just skip using the CaptureManager at all for this.

For #2, the VideoCapturerState could just contain the VideoCapturer directly
instead of having the CaptureRendererAdapter do it.

[perkj_webrtc, 2016/02/08 14:32:00]

I think this can be removed later yes. But since this is currently used I don't
want to grow this cl further. 

  public:
   static CaptureRenderAdapter* Create(VideoCapturer* video_capturer);
   ~CaptureRenderAdapter();
@@ -55,13 +54,13 @@ class CaptureRenderAdapter : public sigslot::has_slots<> {
   void RemoveSink(rtc::VideoSinkInterface<VideoFrame>* sink);
 
   VideoCapturer* video_capturer() { return video_capturer_; }
- private:
 
+ private:
   explicit CaptureRenderAdapter(VideoCapturer* video_capturer);
   void Init();
 
   // Callback for frames received from the capturer.
-  void OnVideoFrame(VideoCapturer* capturer, const VideoFrame* video_frame);
+  void OnFrame(const VideoFrame& frame) override;
 
   // Just pointers since ownership is not handed over to this class.
   std::vector<rtc::VideoSinkInterface<VideoFrame>*> sinks_;