refactor video capture in browser process to support device sharing across multiple renderer proc...

content/browser/renderer_host/media/video_capture_controller_event_handler.h

 // Copyright (c) 2011 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_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_EVENT_HANDLER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_EVENT_HANDLER_H_
 
 #include "base/shared_memory.h"
 #include "base/time.h"
 #include "content/common/content_export.h"
 
 // ID used for identifying an object of VideoCaptureController.
 struct CONTENT_EXPORT VideoCaptureControllerID {
-  VideoCaptureControllerID(int device_id);
+  explicit VideoCaptureControllerID(int device_id);
 
   bool operator<(const VideoCaptureControllerID& vc) const;
+  bool operator==(const VideoCaptureControllerID& vc) const;
 
   int device_id;
 };
 
 // VideoCaptureControllerEventHandler is the interface for
 // VideoCaptureController to notify clients about the events such as
 // BufferReady, FrameInfo, Error, etc.
 class CONTENT_EXPORT VideoCaptureControllerEventHandler {
  public:
   // An Error has occurred in the VideoCaptureDevice.
   virtual void OnError(const VideoCaptureControllerID& id) = 0;
 
   // A buffer has been newly created.
   virtual void OnBufferCreated(const VideoCaptureControllerID& id,
                                base::SharedMemoryHandle handle,
                                int length, int buffer_id) = 0;
 
   // A buffer has been filled with I420 video.
   virtual void OnBufferReady(const VideoCaptureControllerID& id,
                              int buffer_id,
                              base::Time timestamp) = 0;
 
   // The frame resolution the VideoCaptureDevice capture video in.
   virtual void OnFrameInfo(const VideoCaptureControllerID& id,
                            int width,
                            int height,
                            int frame_rate) = 0;
 
   // Report that this object can be deleted.
   virtual void OnReadyToDelete(const VideoCaptureControllerID& id) = 0;

[perkj_chrome, 2011/11/02 09:18:13]

Should you put OnReadyToDelete in a separate interface or use an event if you
make sure VideoCaptureManager creates VideoCaptureControllers? VideoCaptureHost
should not have to care about the lifetime of a controller if
VideoCaptureManager creates and owns it. 

[wjia(left Chromium), 2011/11/03 07:02:02]

I didn't change the function name. It should be OnReadyToRemove or
OnControllerDone. It's a signal telling Host that this controller has got all
buffers back, and Host is free to remove it. This event is always needed.

 
  protected:
   virtual ~VideoCaptureControllerEventHandler() {}
 };
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_EVENT_HANDLER_H_