Update {virtual,override,final} to follow C++11 style in chrome/browser/chromeos/login.

chrome/browser/chromeos/login/auth/auth_prewarmer.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_CHROMEOS_LOGIN_AUTH_AUTH_PREWARMER_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_AUTH_AUTH_PREWARMER_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "chromeos/network/network_state_handler_observer.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
 namespace net {
 class URLRequestContextGetter;
 }  // namespace net
 
 namespace chromeos {
 
 class NetworkState;
 
 // Class for prewarming authentication network connection.
 class AuthPrewarmer : public NetworkStateHandlerObserver,
                       public content::NotificationObserver {
  public:
   AuthPrewarmer();
-  virtual ~AuthPrewarmer();
+  ~AuthPrewarmer() override;
 
   void PrewarmAuthentication(const base::Closure& completion_callback);
 
  private:
   // chromeos::NetworkStateHandlerObserver overrides.
-  virtual void DefaultNetworkChanged(const NetworkState* network) override;
+  void DefaultNetworkChanged(const NetworkState* network) override;
 
   // content::NotificationObserver overrides.
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) override;
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
 
   bool IsNetworkConnected() const;
   net::URLRequestContextGetter* GetRequestContext() const;
   void DoPrewarm();
 
   content::NotificationRegistrar registrar_;
   base::Closure completion_callback_;
   bool doing_prewarm_;
 
   DISALLOW_COPY_AND_ASSIGN(AuthPrewarmer);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_AUTH_AUTH_PREWARMER_H_