Add framerate to VideoSinkWants and ability to signal on overuse

webrtc/media/base/videosourceinterface.h

Index: webrtc/media/base/videosourceinterface.h
diff --git a/webrtc/media/base/videosourceinterface.h b/webrtc/media/base/videosourceinterface.h
index 0ea1c60abfa389e5bc236925e25d9bae74e2886d..3a04ecccd50ea61aff9fd815185f7b006fecb723 100644
--- a/webrtc/media/base/videosourceinterface.h
+++ b/webrtc/media/base/videosourceinterface.h
@@ -34,6 +34,8 @@ struct VideoSinkWants {
   // closest resolution to this pixel count, but if max_pixel_count is set, it
   // still sets the absolute upper bound.
   rtc::Optional<int> target_pixel_count;
+  // Tells the source the maximum framerate the sink wants.
+  rtc::Optional<int> max_framerate_fps;
 };
 
 template <typename VideoFrameT>