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

content/browser/renderer_host/media/media_stream_provider.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.
 
 // MediaStreamProvider is used to capture media of the types defined in
 // MediaStreamType. There is only one MediaStreamProvider instance per media
 // type and a MediaStreamProvider instance can have only one registered
 // listener.
 // The MediaStreamManager is expected to be called on Browser::IO thread and
 // the listener will be called on the same thread.
@@ skipping 49 matching lines @@
 
 // Implemented by a manager class providing captured media.
 class CONTENT_EXPORT MediaStreamProvider
     : public base::RefCountedThreadSafe<MediaStreamProvider> {
  public:
   // Registers a listener and a device message loop.
   virtual void Register(MediaStreamProviderListener* listener,
                         const scoped_refptr<base::SingleThreadTaskRunner>&
                             device_task_runner) = 0;
 
-  // Unregisters the previously registered listener.
-  virtual void Unregister() = 0;
-
   // Enumerates existing capture devices and calls |DevicesEnumerated|.
   virtual void EnumerateDevices(MediaStreamType stream_type) = 0;
 
   // Opens the specified device. The device is not started and it is still
   // possible for other applications to open the device before the device is
   // started. |Opened| is called when the device is opened.
   // kInvalidMediaCaptureSessionId is returned on error.
   virtual int Open(const StreamDeviceInfo& device) = 0;
 
   // Closes the specified device and calls |Closed| when done.
   virtual void Close(int capture_session_id) = 0;
 
  protected:
   friend class base::RefCountedThreadSafe<MediaStreamProvider>;
   virtual ~MediaStreamProvider() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MEDIA_STREAM_PROVIDER_H_