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

content/browser/renderer_host/media/video_capture_manager.h

Index: content/browser/renderer_host/media/video_capture_manager.h
diff --git a/content/browser/renderer_host/media/video_capture_manager.h b/content/browser/renderer_host/media/video_capture_manager.h
index a42fc537ab7c4bb6f56a5bd007f5fac22da23954..e130c6208a59f4fcd4ae2de7134f9e2ce2dca303 100644
--- a/content/browser/renderer_host/media/video_capture_manager.h
+++ b/content/browser/renderer_host/media/video_capture_manager.h
@@ -44,13 +44,13 @@ class CONTENT_EXPORT VideoCaptureManager : public MediaStreamProvider {
   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;