Standardize usage of virtual/override/final in content/

content/public/renderer/render_frame_observer.h

Index: content/public/renderer/render_frame_observer.h
diff --git a/content/public/renderer/render_frame_observer.h b/content/public/renderer/render_frame_observer.h
index 2886f35c2837cffc691317994215cd742886721f..7ad46d7d52c7b376eaec3c9f5bdbabe64b4da248 100644
--- a/content/public/renderer/render_frame_observer.h
+++ b/content/public/renderer/render_frame_observer.h
@@ -75,17 +75,17 @@ class CONTENT_EXPORT RenderFrameObserver : public IPC::Listener,
   virtual void DidCommitCompositorFrame() {}
 
   // IPC::Listener implementation.
-  virtual bool OnMessageReceived(const IPC::Message& message) override;
+  bool OnMessageReceived(const IPC::Message& message) override;
 
   // IPC::Sender implementation.
-  virtual bool Send(IPC::Message* message) override;
+  bool Send(IPC::Message* message) override;
 
   RenderFrame* render_frame() const;
   int routing_id() const { return routing_id_; }
 
  protected:
   explicit RenderFrameObserver(RenderFrame* render_frame);
-  virtual ~RenderFrameObserver();
+  ~RenderFrameObserver() override;
 
  private:
   friend class RenderFrameImpl;