Standardize usage of virtual/override/final in chrome/browser/

chrome/browser/guest_view/mime_handler_view/chrome_mime_handler_view_guest_delegate.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_GUEST_VIEW_MIME_HANDLER_VIEW_CHROME_MIME_HANDLER_VIEW_GUEST_DELEGATE_H_
 #define CHROME_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_CHROME_MIME_HANDLER_VIEW_GUEST_DELEGATE_H_
 
 #include "extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h"
 
 namespace content {
 class WebContents;
 }  // namespace content
 
 class ChromeMimeHandlerViewGuestDelegate
     : public extensions::MimeHandlerViewGuestDelegate {
  public:
   explicit ChromeMimeHandlerViewGuestDelegate(
       extensions::MimeHandlerViewGuest* guest);
-  virtual ~ChromeMimeHandlerViewGuestDelegate();
+  ~ChromeMimeHandlerViewGuestDelegate() override;
 
   // MimeHandlerViewGuestDelegate.
-  virtual void AttachHelpers() override;
-  virtual void ChangeZoom(bool zoom_in) override;
+  void AttachHelpers() override;
+  void ChangeZoom(bool zoom_in) override;
 
  private:
   extensions::MimeHandlerViewGuest* guest_;  // Owns us.
 
   DISALLOW_COPY_AND_ASSIGN(ChromeMimeHandlerViewGuestDelegate);
 };
 
 #endif  // CHROME_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_CHROME_MIME_HANDLER_VIEW_GUEST_DELEGATE_H_