Add callback to copy texture backed frames in WebRtcVideoFrameAdapter

content/renderer/media/webrtc/webrtc_video_capturer_adapter.h

 // Copyright 2014 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 CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_VIDEO_CAPTURER_ADAPTER_H_
 #define CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_VIDEO_CAPTURER_ADAPTER_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #include "content/common/content_export.h"
+#include "content/renderer/media/webrtc/webrtc_video_frame_adapter.h"
 #include "media/base/video_capture_types.h"
 #include "media/base/video_frame.h"
 #include "media/base/video_frame_pool.h"
+#include "media/renderers/skcanvas_video_renderer.h"
 #include "third_party/webrtc/media/base/videocapturer.h"
 
+namespace base {
+class WaitableEvent;
+}  // namespace base
+
 namespace content {
 
+class ContextProviderCommandBuffer;
+
 // WebRtcVideoCapturerAdapter implements a simple cricket::VideoCapturer that is
 // used for VideoCapturing in libJingle and especially in PeerConnections.
 // The class is created and destroyed on the main render thread.
 // PeerConnection access cricket::VideoCapturer from a libJingle worker thread.
 // An instance of WebRtcVideoCapturerAdapter is owned by an instance of
 // webrtc::VideoTrackSourceInterface in libJingle. The implementation of
 // webrtc::VideoTrackSourceInterface guarantees that this object is not deleted
 // while it is still used in libJingle.
 class CONTENT_EXPORT WebRtcVideoCapturerAdapter
     : NON_EXPORTED_BASE(public cricket::VideoCapturer) {
@@ skipping 11 matching lines @@
   // These methods are accessed from a libJingle worker thread.
   cricket::CaptureState Start(
       const cricket::VideoFormat& capture_format) override;
   void Stop() override;
   bool IsRunning() override;
   bool GetPreferredFourccs(std::vector<uint32_t>* fourccs) override;
   bool GetBestCaptureFormat(const cricket::VideoFormat& desired,
                             cricket::VideoFormat* best_format) override;
   bool IsScreencast() const override;
 
+  void CopyTextureFrame(
+      const scoped_refptr<media::VideoFrame>& frame,
+      scoped_refptr<media::VideoFrame>* new_frame);
+  void CopyTextureFrameOnMainThread(
+      const scoped_refptr<media::VideoFrame>& frame,
+      scoped_refptr<media::VideoFrame>* new_frame,
+      base::WaitableEvent* waiter);

[mcasas, 2016/10/26 16:06:02]

I see with worry the existence of |base::WaitableEvent|
but I guess it's necessary and inevitable. Could you plz
add a comment in these methods explaining that 
CopyTextureFrame() is going to block until the copy
on Main Thread is finished? 

[emircan, 2016/10/27 00:37:56]

I added comments explaining it. Unfortunately, I couldn't find a way to do it
anywhere else than main thread for texture copy.

+  const scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
+  const scoped_refptr<ContextProviderCommandBuffer> provider_;
+  media::SkCanvasVideoRenderer canvas_video_renderer_;
+  WebRtcVideoFrameAdapter::CopyTextureFrameCallback copy_texture_callback_;
+
   // |thread_checker_| is bound to the libjingle worker thread.
   base::ThreadChecker thread_checker_;
 
   const bool is_screencast_;
   bool running_;
 
   media::VideoFramePool scaled_frame_pool_;
 
+  base::WeakPtrFactory<WebRtcVideoCapturerAdapter> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(WebRtcVideoCapturerAdapter);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_VIDEO_CAPTURER_ADAPTER_H_