Update {virtual,override,final} to follow C++11 style in ash.

ash/system/chromeos/network/network_detailed_view.h

 // Copyright (c) 2012 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 ASH_SYSTEM_CHROMEOS_NETWORK_NETWORK_DETAILED_VIEW_H
 #define ASH_SYSTEM_CHROMEOS_NETWORK_NETWORK_DETAILED_VIEW_H
 
 #include "ash/system/tray/tray_details_view.h"
 #include "chromeos/network/network_state_handler.h"
 
@@ skipping 17 matching lines @@
   virtual void Init() = 0;
 
   virtual DetailedViewType GetViewType() const = 0;
 
   // Called when the contents of the network list have changed or when any
   // Manager properties (e.g. technology state) have changed.
   // (Called only from TrayNetworkStateObserver).
   virtual void Update() = 0;
 
  protected:
-  virtual ~NetworkDetailedView() {}
+  ~NetworkDetailedView() override {}
 };
 
 }  // namespace tray
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_NETWORK_NETWORK_DETAILED_VIEW_H