Remove stop method from VideoTrackSourceInterface.

webrtc/api/videotracksource.h

Index: webrtc/api/videotracksource.h
diff --git a/webrtc/api/videotracksource.h b/webrtc/api/videotracksource.h
index 1d1d579d614d0321d4d4e3f56340772b771e0cc4..67e764fd40e5ad48f45d5fc746027263b408ae4b 100644
--- a/webrtc/api/videotracksource.h
+++ b/webrtc/api/videotracksource.h
@@ -33,8 +33,6 @@ class VideoTrackSource : public Notifier<VideoTrackSourceInterface> {
   SourceState state() const override { return state_; }
   bool remote() const override { return remote_; }
 
-  void Stop() override{};
-
   bool is_screencast() const override { return false; }
   rtc::Optional<bool> needs_denoising() const override {
     return rtc::Optional<bool>(); }