[Cast] VideoFrameFactory interface to vend frames with encoder affinity.

media/cast/cast_sender.h

Index: media/cast/cast_sender.h
diff --git a/media/cast/cast_sender.h b/media/cast/cast_sender.h
index 7615c28602c8f58052f4f7bf024c4eba79bc6bcc..8ac9f014ea0acf323626463cc99bc4e3cbd2b29a 100644
--- a/media/cast/cast_sender.h
+++ b/media/cast/cast_sender.h
@@ -36,6 +36,11 @@ class VideoFrameInput : public base::RefCountedThreadSafe<VideoFrameInput> {
       const scoped_refptr<media::VideoFrame>& video_frame,
       const base::TimeTicks& capture_time) = 0;
 
+  // Creates a |VideoFrame| suitable for input via |InsertRawVideoFrame|. Frames
+  // obtained in this manner may provide benefits such memory reuse and affinity
+  // with the encoder. The format is guaranteed to be I420 or NV12.
+  virtual scoped_refptr<VideoFrame> CreateFrame(base::TimeDelta timestamp) = 0;

[Alpha Left Google, 2014/11/17 20:23:14]

What if CastSender is not yet initialized? Then there won't be an encoder and
this method wouldn't know what kind of frames to create. Code change is not
needed, I think you just need to clarify in comments.

[jfroy, 2014/11/17 21:23:05]

OK, I'll clarify that if the initialization status is not video initialized,
you'll get back null. I thought I didn't need to clarify because if video
initialization fails, CastSender does not create a VideoFrameInput object and
thus you won't ever be able to call that method.

[Alpha Left Google, 2014/11/18 02:57:58]

You're right. VideoFrameInput is not available until video sending is
initialized.

+
  protected:
   virtual ~VideoFrameInput() {}