Refactor video capturing code in the render process

media/video/capture/video_capture.h

-// Copyright (c) 2012 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.
-//
-// This file contains abstract classes used for media filter to handle video
-// capture devices.
-
-#ifndef MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_H_
-#define MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_H_
-
-#include "base/callback.h"
-#include "base/memory/ref_counted.h"
-#include "base/time/time.h"
-#include "media/base/media_export.h"
-#include "media/video/capture/video_capture_types.h"
-
-namespace media {
-
-class VideoFrame;
-
-class MEDIA_EXPORT VideoCapture {
- public:
-  // TODO(wjia): add error codes.
-  // TODO(wjia): support weak ptr.
-  // Callbacks provided by client for notification of events.
-  class MEDIA_EXPORT EventHandler {
-   public:
-    // Notify client that video capture has been started.
-    virtual void OnStarted(VideoCapture* capture) = 0;
-
-    // Notify client that video capture has been stopped.
-    virtual void OnStopped(VideoCapture* capture) = 0;
-
-    // Notify client that video capture has been paused.
-    virtual void OnPaused(VideoCapture* capture) = 0;
-
-    // Notify client that video capture has hit some error |error_code|.
-    virtual void OnError(VideoCapture* capture, int error_code) = 0;
-
-    // Notify client that the client has been removed and no more calls will be
-    // received.
-    virtual void OnRemoved(VideoCapture* capture) = 0;
-
-    // Notify client that a buffer is available.
-    virtual void OnFrameReady(
-        VideoCapture* capture,
-        const scoped_refptr<media::VideoFrame>& frame) = 0;
-
-   protected:
-    virtual ~EventHandler() {}
-  };
-
-  typedef base::Callback<void(const media::VideoCaptureFormats&)>
-      DeviceFormatsCallback;
-
-  typedef base::Callback<void(const media::VideoCaptureFormats&)>
-      DeviceFormatsInUseCallback;
-
-  VideoCapture() {}
-
-  // Request video capture to start capturing with |params|.
-  // Also register |handler| with video capture for event handling.
-  // |handler| must remain valid until it has received |OnRemoved()|.
-  virtual void StartCapture(EventHandler* handler,
-                            const VideoCaptureParams& params) = 0;
-
-  // Request video capture to stop capturing for client |handler|.
-  // |handler| must remain valid until it has received |OnRemoved()|.
-  virtual void StopCapture(EventHandler* handler) = 0;
-
-  virtual bool CaptureStarted() = 0;
-  virtual int CaptureFrameRate() = 0;
-
-  // Request the device capture supported formats. This method can be called
-  // before startCapture() and/or after stopCapture() so a |callback| is used
-  // instead of replying via EventHandler.
-  virtual void GetDeviceSupportedFormats(
-      const DeviceFormatsCallback& callback) = 0;
-
-  // Request the device capture in-use format(s), possibly by other user(s) in
-  // other renderer(s). If there is no format in use, the vector returned in
-  // the callback will be empty.
-  virtual void GetDeviceFormatsInUse(
-      const DeviceFormatsInUseCallback& callback) = 0;
-
- protected:
-  virtual ~VideoCapture() {}
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(VideoCapture);
-};
-
-}  // namespace media
-
-#endif  // MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_H_