Add StreamTextureWrapper/StreamTextureWrapperImpl

media/blink/stream_texture_wrapper.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_BLINK_STREAM_TEXTURE_WRAPPER_H_

[watk, 2016/07/23 03:13:40]

Does this need to go in media/blink for some reason? Just seems like a strange
place. media/base/android?

[tguilbert, 2016/07/26 00:13:52]

I had it in media/base/android earlier, but ran into dep check errors. It needs
to live in media/blink because it is including cc/layers.

I opened 631178 to address this issue, because also changing StreamTextureProxy
is beyond the scope of this CL.

+#define MEDIA_BLINK_STREAM_TEXTURE_WRAPPER_H_
+
+#include "cc/layers/video_frame_provider.h"
+#include "media/base/video_frame.h"
+
+namespace media {
+class VideoFrame;
+
+// StreamTextureWrapper encapsulates a StreamTexture's creation, initialization
+// and registration for latter retrieval (in the Browser process).

[watk, 2016/07/23 03:13:40]

later

[tguilbert, 2016/07/26 00:13:52]

Done.

+//
+// TODO(tguilbert): Support registering the underlying SurfaceTexture so it can
+// be used by a MediaPlayer in the browser process. See crbug.com/627658.
+class MEDIA_EXPORT StreamTextureWrapper {
+ public:
+  StreamTextureWrapper() {}
+  virtual ~StreamTextureWrapper() {}

[liberato (no reviews please), 2016/07/22 16:13:57]

since this has special requirements for delete, maybe make this (and ~Impl)
protected.  not sure if it actually works.  :)

[tguilbert, 2016/07/26 00:13:52]

I have moved this destructor to protected.

It does not work for StreamTextureWrapperImpl however, since Destroy uses
main_thread_task_runner_->DeleteSoon(), which uses the public destructor.

I could change the Destroy() to instead post to the main thread and then call
"delete this", but I am not familiar with all the possible implications of such
a change...

Do you have any preferences?

+
+  // Initialize the StreamTexture and wrap the underlying texture into a frame.
+  // The provided |compositor_task_runner| will be used to "signal" new frames
+  // to |client|.

[watk, 2016/07/23 03:13:40]

should be a comment about where/when init_cb is run.

[tguilbert, 2016/07/26 00:13:52]

Done.

+  virtual void Initialize(
+      cc::VideoFrameProvider::Client* client,
+      const gfx::Size& natural_size,
+      scoped_refptr<base::SingleThreadTaskRunner> compositor_task_runner,
+      const base::Closure& init_cb) = 0;
+
+  // Should be called whenever the Video's natural size changes.

[watk, 2016/07/23 03:13:40]

uncapitalize Video

[tguilbert, 2016/07/26 00:13:52]

Done.

+  virtual void UpdateTextureSize(const gfx::Size& natural_size) = 0;
+
+  // Returns the latest frame.
+  // N.B: The frame returned is likely always the same frame, wrapping the
+  // underlying texture. See StreamTextureWrapperImpl for more details.
+  virtual scoped_refptr<VideoFrame> GetCurrentFrame() = 0;
+
+  // Safely destroys the StreamTextureWrapper on the appropritate thread.

[watk, 2016/07/23 03:13:40]

appropriate

I would delete the comment about threading on the interface. The caller doesn't
care about that implementation detail.

[watk, 2016/07/25 21:47:14]

Actually, I was thinking about this. I think the reason it's hard to write good
docs for this is because its only reason for existing is that we have to put
STWI in content. As a result we end up duplicating the docs on STW and STWI and
they're likely to go out of sync. Maybe you should just write something like:
See StreamTextureWrapperImpl. 

[tguilbert, 2016/07/26 00:13:52]

I did it one way in this patch. I can also remove all function comments except
"See StreamTextureWrapperImpl" to truly force readers to see the latest
comments.

[tguilbert, 2016/07/26 00:13:52]

Done.

+  virtual void Destroy() = 0;
+};
+
+}  // namespace media
+
+namespace std {
+
+// Specialize std::default_delete so that
+// std::unique_ptr<StreamTextureWrapper> uses "Destroy()" instead of trying to
+// use the destructor.
+template <>
+struct MEDIA_EXPORT default_delete<media::StreamTextureWrapper> {
+  void operator()(media::StreamTextureWrapper* stw) const;
+};
+
+}  // namespace std
+
+#endif  // MEDIA_BLINK_STREAM_TEXTURE_WRAPPER_H_