Remove pure-virtual MediaStreamProvider::Unregister method and make overrides non-virtual.

content/browser/renderer_host/media/video_capture_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.
 
 // VideoCaptureManager is used to open/close, start/stop, enumerate available
 // video capture devices, and manage VideoCaptureController's.
 // All functions are expected to be called from Browser::IO thread. Some helper
 // functions (*OnDeviceThread) will dispatch operations to the device thread.
 // VideoCaptureManager will open OS dependent instances of VideoCaptureDevice.
 // A device can only be opened once.
@@ skipping 26 matching lines @@
 // VideoCaptureManager opens/closes and start/stops video capture devices.
 class CONTENT_EXPORT VideoCaptureManager : public MediaStreamProvider {
  public:
   // Callback used to signal the completion of a controller lookup.
   typedef base::Callback<
       void(const base::WeakPtr<VideoCaptureController>&)> DoneCB;
 
   explicit VideoCaptureManager(
       scoped_ptr<media::VideoCaptureDeviceFactory> factory);
 
+  void Unregister();
+
   // Implements MediaStreamProvider.
   void Register(MediaStreamProviderListener* listener,
                 const scoped_refptr<base::SingleThreadTaskRunner>&
                     device_task_runner) override;
 
-  void Unregister() override;
-
   void EnumerateDevices(MediaStreamType stream_type) override;
 
   int Open(const StreamDeviceInfo& device) override;
 
   void Close(int capture_session_id) override;
 
   // Called by VideoCaptureHost to locate a capture device for |capture_params|,
   // adding the Host as a client of the device's controller if successful. The
   // value of |session_id| controls which device is selected;
   // this value should be a session id previously returned by Open().
@@ skipping 192 matching lines @@
   // Accessed on the device thread only.
   std::map<media::VideoCaptureSessionId, gfx::NativeViewId>
       notification_window_ids_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_MANAGER_H_