Make painting a single frame a permanent API on VideoRendererSink.

media/filters/video_renderer_algorithm.h

Index: media/filters/video_renderer_algorithm.h
diff --git a/media/filters/video_renderer_algorithm.h b/media/filters/video_renderer_algorithm.h
index 24e648411da850a0249ce6969092e2ac8f4627e1..b5ce7932c223d29c156f6341b65f0f533f738a22 100644
--- a/media/filters/video_renderer_algorithm.h
+++ b/media/filters/video_renderer_algorithm.h
@@ -136,6 +136,8 @@ class MEDIA_EXPORT VideoRendererAlgorithm {
 
   size_t frames_queued() const { return frame_queue_.size(); }
 
+  scoped_refptr<VideoFrame> first_frame() { return frame_queue_.front().frame; }
+
   // Returns the average of the duration of all frames in |frame_queue_|
   // as measured in wall clock (not media) time.
   base::TimeDelta average_frame_duration() const {