MojoVideoDecoder: Plumb metadata methods.

media/base/video_decoder.h

Index: media/base/video_decoder.h
diff --git a/media/base/video_decoder.h b/media/base/video_decoder.h
index 51dad81987b8e5f85159b05ebf79e56ab4a498ad..95fd7fc3edd9f08a81a881c1a36e89a0c784c6f9 100644
--- a/media/base/video_decoder.h
+++ b/media/base/video_decoder.h
@@ -79,8 +79,7 @@ class MEDIA_EXPORT VideoDecoder {
   // frame are returned via the provided callback. Some decoders may allow
   // decoding multiple buffers in parallel. Callers should call
   // GetMaxDecodeRequests() to get number of buffers that may be decoded in
-  // parallel. Decoder must call |decode_cb| in the same order in which Decode()
-  // is called.
+  // parallel.
   //
   // Implementations guarantee that the |decode_cb| will not be called from
   // within this method, and that it will be called even if Decode() is never