Allow VideoCaptureImpl to suspend/resume frame delivery to its client.

content/renderer/media/video_capture_impl_manager.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.
 
 // VideoCaptureImplManager manages video capture devices in renderer process.
 // The video capture clients use AddDevice() to get a pointer to
 // video capture device. VideoCaputreImplManager supports multiple clients
 // accessing same device.
 
 #ifndef CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_MANAGER_H_
@@ skipping 24 matching lines @@
   // operate on that pointer, such as StartCaptrue, StopCapture.
   virtual media::VideoCapture* AddDevice(
       media::VideoCaptureSessionId id,
       media::VideoCapture::EventHandler* handler);
 
   // Called by video capture client |handler| to remove device referenced
   // by |id| from VideoCaptureImplManager's list of opened device list.
   virtual void RemoveDevice(media::VideoCaptureSessionId id,
                             media::VideoCapture::EventHandler* handler);
 
+  // Make all existing VideoCaptureImpl instances stop/resume delivering
+  // video frames to their clients, depends on flag |suspend|.
+  virtual void SuspendDevices(bool suspend);
+
   VideoCaptureMessageFilter* video_capture_message_filter() const {
     return filter_;
   }
 
  protected:
   virtual ~VideoCaptureImplManager();
 
  private:
   friend class base::RefCountedThreadSafe<VideoCaptureImplManager>;
 
@@ skipping 14 matching lines @@
   scoped_refptr<VideoCaptureMessageFilter> filter_;
   base::Thread thread_;
   scoped_refptr<base::MessageLoopProxy> message_loop_proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureImplManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_MANAGER_H_