media: Create Mojo StructTraits for VideoFrame

media/mojo/clients/mojo_decryptor.h

Index: media/mojo/clients/mojo_decryptor.h
diff --git a/media/mojo/clients/mojo_decryptor.h b/media/mojo/clients/mojo_decryptor.h
index 8b889574c4fa90acc45795947849a1021eaf3850..e51ba71b7aa3eda3bd046f2ad8931b41668f3d87 100644
--- a/media/mojo/clients/mojo_decryptor.h
+++ b/media/mojo/clients/mojo_decryptor.h
@@ -63,7 +63,7 @@ class MojoDecryptor : public Decryptor {
                       std::vector<mojom::AudioBufferPtr> audio_buffers);
   void OnVideoDecoded(const VideoDecodeCB& video_decode_cb,
                       Status status,
-                      mojom::VideoFramePtr video_frame,
+                      const scoped_refptr<VideoFrame>& video_frame,

[xhwang, 2017/06/06 05:51:15]

The current style guide discourages using const-ref for scoped_refptr. Just pass
by value and use std::move where needed?

[sandersd (OOO until July 31), 2017/06/06 18:07:37]

Yes, but this callback is used as a Decryptor::DecryptAndDecodeVideoCallback,
which after the StructTraits change looks like this:

  using DecryptAndDecodeVideoCallback =
base::Callback<void(media::Decryptor::Status, const
scoped_refptr<media::VideoFrame>&, FrameResourceReleaserPtr)>;

There isn't really much choice here.

[xhwang, 2017/06/06 18:12:47]

I see. So it's more like a binding generation issue. Nevermind then.

[dcheng, 2017/06/08 09:41:08]

It is possible to annotate the type with move_only so you'll get move semantics:
https://cs.chromium.org/chromium/src/mojo/common/file.typemap?rcl=119d0e85eb5...

Though I think it's probably not necessary here (and it's not really even true,
since scoped_refptr is not move_only =)

                       mojom::FrameResourceReleaserPtr releaser);
 
   base::ThreadChecker thread_checker_;