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

chrome/browser/services/gcm/push_messaging_permission_context.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_SERVICES_GCM_PUSH_MESSAGING_PERMISSION_CONTEXT_H_
 #define CHROME_BROWSER_SERVICES_GCM_PUSH_MESSAGING_PERMISSION_CONTEXT_H_
 
 #include "chrome/browser/content_settings/permission_context_base.h"
 
 namespace gcm {
 
 // Permission context for push messages.
 class PushMessagingPermissionContext : public PermissionContextBase {
  public:
   explicit PushMessagingPermissionContext(Profile* profile);
-  virtual ~PushMessagingPermissionContext();
+  ~PushMessagingPermissionContext() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PushMessagingPermissionContext);
 };
 
 }  // namespace gcm
 #endif  // CHROME_BROWSER_SERVICES_GCM_PUSH_MESSAGING_PERMISSION_CONTEXT_H_