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

ash/display/projecting_observer_chromeos.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 ASH_DISPLAY_PROJECTING_OBSERVER_CHROMEOS_H_
 #define ASH_DISPLAY_PROJECTING_OBSERVER_CHROMEOS_H_
 
 #include "ash/ash_export.h"
 #include "ui/display/chromeos/display_configurator.h"
 
 namespace chromeos {
 class PowerManagerClient;
 }
 
 namespace ash {
 
 class ASH_EXPORT ProjectingObserver : public ui::DisplayConfigurator::Observer {
  public:
   // |power_manager_client| must outlive this object.
   explicit ProjectingObserver(
       chromeos::PowerManagerClient* power_manager_client);
-  virtual ~ProjectingObserver();
+  ~ProjectingObserver() override;
 
   // Called when a casting session is started or stopped.
   void OnCastingSessionStartedOrStopped(bool started);
 
   // DisplayConfigurator::Observer implementation:
-  virtual void OnDisplayModeChanged(
+  void OnDisplayModeChanged(
       const ui::DisplayConfigurator::DisplayStateList& outputs) override;
 
  private:
   // Sends the current projecting state to power manager.
   void SetIsProjecting();
 
   // True if at least one output is internal. This value is updated when
   // |OnDisplayModeChanged| is called.
   bool has_internal_output_;
 
   // Keeps track of the number of connected outputs.
   int output_count_;
 
   // Number of outstanding casting sessions.
   int casting_session_count_;
 
   // Weak pointer to the DBusClient PowerManagerClient;
   chromeos::PowerManagerClient* power_manager_client_;
 
   DISALLOW_COPY_AND_ASSIGN(ProjectingObserver);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_PROJECTING_OBSERVER_CHROMEOS_H_