Refactor video capturing code in the render process

content/renderer/media/media_stream_video_capturer_source.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_MEDIA_STREAM_VIDEO_CAPTURER_SOURCE_H_
 #define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_VIDEO_CAPTURER_SOURCE_H_
 
 #include "base/callback.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/threading/thread_checker.h"
 #include "content/common/media/video_capture.h"
 #include "content/renderer/media/media_stream_video_source.h"
-#include "media/video/capture/video_capture.h"
 
 namespace content {
 
-class VideoCaptureHandle;
-
 // VideoCapturerDelegate is a delegate used by MediaStreamVideoCapturerSource
 // for local video capturer. It uses VideoCaptureImplManager to start / stop
 // and receive I420 frames from Chrome's video capture implementation.
+//
+// This is a render thread only object.
 class CONTENT_EXPORT VideoCapturerDelegate
-    : public media::VideoCapture::EventHandler,
-      public base::RefCountedThreadSafe<VideoCapturerDelegate> {
+    : public base::RefCountedThreadSafe<VideoCapturerDelegate> {
  public:
-  typedef base::Callback<void(const scoped_refptr<media::VideoFrame>&)>
-      NewFrameCallback;
   typedef base::Callback<void(bool running)> StartedCallback;
-  typedef base::Callback<void(const media::VideoCaptureFormats& formats)>
-      SupportedFormatsCallback;
 
   explicit VideoCapturerDelegate(
       const StreamDeviceInfo& device_info);
 
   // Collects the formats that can currently be used.
   // |max_requested_height| and |max_requested_width| is used by Tab and Screen
   // capture to decide what resolution to generate.
   // |callback| is triggered when the formats have been collected.
   virtual void GetCurrentSupportedFormats(
       int max_requested_width,
       int max_requested_height,
-      const SupportedFormatsCallback& callback);
+      const VideoCaptureDeviceFormatsCB& callback);
 
   // Starts deliver frames using the resolution in |params|.
   // |new_frame_callback| is triggered when a new video frame is available.
   // |started_callback| is triggered before the first video frame is received
   // or if the underlying video capturer fails to start.
-  virtual void StartDeliver(
+  virtual void StartToDeliver(

[Ami GONE FROM CHROMIUM, 2014/04/24 21:04:31]

From earlier: why is this not StartCapture?

[Alpha Left Google, 2014/04/24 22:50:34]

Done.

       const media::VideoCaptureParams& params,
-      const NewFrameCallback& new_frame_callback,
+      const VideoCaptureDeliverFrameCB& new_frame_callback,
       const StartedCallback& started_callback);
 
   // Stops deliver frames and clears all callbacks including the
   // SupportedFormatsCallback callback.
   virtual void StopDeliver();
 
- protected:
-  // media::VideoCapture::EventHandler implementation.
-  // These functions are called on the IO thread (same as where
-  // |capture_engine_| runs).
-  virtual void OnStarted(media::VideoCapture* capture) OVERRIDE;
-  virtual void OnStopped(media::VideoCapture* capture) OVERRIDE;
-  virtual void OnPaused(media::VideoCapture* capture) OVERRIDE;
-  virtual void OnError(media::VideoCapture* capture, int error_code) OVERRIDE;
-  virtual void OnRemoved(media::VideoCapture* capture) OVERRIDE;
-  virtual void OnFrameReady(
-      media::VideoCapture* capture,
-      const scoped_refptr<media::VideoFrame>& frame) OVERRIDE;
-
  private:
   friend class base::RefCountedThreadSafe<VideoCapturerDelegate>;
   friend class MockVideoCapturerDelegate;
 
   virtual ~VideoCapturerDelegate();
 
   void OnFrameReadyOnRenderThread(
-      media::VideoCapture* capture,
-      const scoped_refptr<media::VideoFrame>& frame);
-  void OnErrorOnRenderThread(media::VideoCapture* capture);
+      const scoped_refptr<media::VideoFrame>& frame,
+      const media::VideoCaptureFormat& format,
+      const base::TimeTicks& timestamp);
+  void OnStateUpdateOnRenderThread(VideoCaptureState state);
   void OnDeviceFormatsInUseReceived(const media::VideoCaptureFormats& formats);
   void OnDeviceSupportedFormatsEnumerated(
       const media::VideoCaptureFormats& formats);
 
   // The id identifies which video capture device is used for this video
   // capture session.
   media::VideoCaptureSessionId session_id_;
-  scoped_ptr<VideoCaptureHandle> capture_engine_;
+  base::Closure release_device_cb_;
+  base::Closure stop_capture_cb_;
 
   bool is_screen_cast_;
 
-  // Accessed on the thread where StartDeliver is called.
+  // Accessed on the thread where StartToDeliver is called.

[Ami GONE FROM CHROMIUM, 2014/04/24 21:04:31]

l.20 told me that this class is only accessed on a single thread.  Is this
comment outdated?

[Alpha Left Google, 2014/04/24 22:50:34]

This comment is not necessary.

   bool got_first_frame_;
 
-  // |new_frame_callback_| is provided to this class in StartDeliver and must be
-  // valid until StopDeliver is called.
-  NewFrameCallback new_frame_callback_;
-  // |started_callback| is provided to this class in StartDeliver and must be
+  // |new_frame_callback_| is provided to this class in StartToDeliver and must
+  // be valid until StopDeliver is called.
+  VideoCaptureDeliverFrameCB new_frame_callback_;
+  // |started_callback| is provided to this class in StartToDeliver and must be
   // valid until StopDeliver is called.
   StartedCallback started_callback_;
-  // Message loop of the caller of StartDeliver.
-  scoped_refptr<base::MessageLoopProxy> message_loop_proxy_;
 
-  SupportedFormatsCallback source_formats_callback_;
+  VideoCaptureDeviceFormatsCB source_formats_callback_;
+
+  // Bound to the render thread.
+  base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoCapturerDelegate);
 };
 
 class CONTENT_EXPORT MediaStreamVideoCapturerSource

[Ami GONE FROM CHROMIUM, 2014/04/24 21:04:31]

doco thread & lifecycle (who owns it, when is it destroyed, etc) for this class.

[Alpha Left Google, 2014/04/24 22:50:34]

Done.

     : public MediaStreamVideoSource {
  public:
   MediaStreamVideoCapturerSource(
       const StreamDeviceInfo& device_info,
       const SourceStoppedCallback& stop_callback,
       const scoped_refptr<VideoCapturerDelegate>& delegate);
 
   virtual ~MediaStreamVideoCapturerSource();
 
  protected:
@@ skipping 10 matching lines @@
  private:
   // The delegate that provides video frames.
   scoped_refptr<VideoCapturerDelegate> delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaStreamVideoCapturerSource);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_VIDEO_CAPTURER_SOURCE_H_