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..1c9822044ce642463ae045455f28887149808cff 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_;

[nisse-webrtc, 2017/03/08 08:08:54]

Consider changing it to non-optional with default value,

  int max_framerate_fps_ = std::numeric_limits<int>::max();

Could do the same to max_pixel_count, of course.

That would simplify the logic in several places.

[kthelgason, 2017/03/08 08:15:59]

I endorse this comment!

[sprang_webrtc, 2017/03/09 13:19:34]

It might simplify it in some places, like videobroadcaster.
It will make it uglier in others, where we'll have to change
  if (!foo.max_framerate_fps_)
to
  if (foo_max_framerate_fps_ == std::numeric_limits<int>::max())

I suggest we save this for an impending overhaul of the entire struct.

 };
 
 template <typename VideoFrameT>