Replace SetCapturer and SetCaptureDevice by SetSource.

webrtc/api/videotracksource.h

Index: webrtc/api/videotracksource.h
diff --git a/webrtc/api/videotracksource.h b/webrtc/api/videotracksource.h
index 78577aaba23b1f4e4efe345a3cf5fd4e875c8b28..76baa40ed1c94f77d6c5a612c507978e44ebe0a8 100644
--- a/webrtc/api/videotracksource.h
+++ b/webrtc/api/videotracksource.h
@@ -43,8 +43,6 @@ class VideoTrackSource : public Notifier<VideoTrackSourceInterface> {
                        const rtc::VideoSinkWants& wants) override;
   void RemoveSink(rtc::VideoSinkInterface<cricket::VideoFrame>* sink) override;
 
-  cricket::VideoCapturer* GetVideoCapturer() override { return nullptr; }
-
  protected:
   rtc::Thread* worker_thread() { return worker_thread_; }