Standardize usage of virtual/override/final in content/renderer/

content/renderer/media/media_stream_dispatcher.h

Index: content/renderer/media/media_stream_dispatcher.h
diff --git a/content/renderer/media/media_stream_dispatcher.h b/content/renderer/media/media_stream_dispatcher.h
index 41410ac17e2dfc61714e7b15380b2abdd4e56e83..74a06dc384a68f02fa52c27505515029ce19bb7b 100644
--- a/content/renderer/media/media_stream_dispatcher.h
+++ b/content/renderer/media/media_stream_dispatcher.h
@@ -35,7 +35,7 @@ class CONTENT_EXPORT MediaStreamDispatcher
       public base::SupportsWeakPtr<MediaStreamDispatcher> {
  public:
   explicit MediaStreamDispatcher(RenderFrame* render_frame);
-  virtual ~MediaStreamDispatcher();
+  ~MediaStreamDispatcher() override;
 
   // Request a new media stream to be created.
   // This can be used either by WebKit or a plugin.
@@ -111,9 +111,9 @@ class CONTENT_EXPORT MediaStreamDispatcher
   struct Stream;
 
   // RenderFrameObserver override.
-  virtual void OnDestruct() override;
-  virtual bool Send(IPC::Message* message) override;
-  virtual bool OnMessageReceived(const IPC::Message& message) override;
+  void OnDestruct() override;
+  bool Send(IPC::Message* message) override;
+  bool OnMessageReceived(const IPC::Message& message) override;
 
   // Messages from the browser.
   void OnStreamGenerated(