Standardize usage of virtual/override/final specifiers.

chrome/browser/ui/views/frame/browser_command_handler_x11.h

 // Copyright 2014 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_COMMAND_HANDLER_X11_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_COMMAND_HANDLER_X11_H_
 
 #include "ui/events/event_handler.h"
 
 class Browser;
 
 class BrowserCommandHandlerX11 : public ui::EventHandler {
  public:
   explicit BrowserCommandHandlerX11(Browser* browser);
-  virtual ~BrowserCommandHandlerX11();
+  ~BrowserCommandHandlerX11() override;
 
  private:
   // ui::EventHandler:
-  virtual void OnMouseEvent(ui::MouseEvent* event) override;
+  void OnMouseEvent(ui::MouseEvent* event) override;
 
   Browser* browser_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserCommandHandlerX11);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_COMMAND_HANDLER_X11_H_