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

ash/ash_touch_exploration_manager_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_TOUCH_EXPLORATION_MANAGER_CHROMEOS_H_
 #define ASH_TOUCH_EXPLORATION_MANAGER_CHROMEOS_H_
 
 #include "ash/ash_export.h"
 #include "ash/system/tray_accessibility.h"
 #include "ui/chromeos/touch_exploration_controller.h"
 
 namespace chromeos {
 class CrasAudioHandler;
 }
 
 namespace ash {
 class RootWindowController;
 
 // Responsible for initializing TouchExplorationController when spoken
 // feedback is on for ChromeOS only. This class implements
 // TouchExplorationControllerDelegate which allows touch gestures to manipulate
 // the system.
 class ASH_EXPORT AshTouchExplorationManager
     : public ash::AccessibilityObserver,
       public ui::TouchExplorationControllerDelegate {
  public:
   explicit AshTouchExplorationManager(
       RootWindowController* root_window_controller);
-  virtual ~AshTouchExplorationManager();
+  ~AshTouchExplorationManager() override;
 
   // AccessibilityObserver overrides:
-  virtual void OnAccessibilityModeChanged(
+  void OnAccessibilityModeChanged(
       ui::AccessibilityNotificationVisibility notify) override;
 
   // TouchExplorationControllerDelegate overrides:
-  virtual void SetOutputLevel(int volume) override;
-  virtual void SilenceSpokenFeedback() override;
-  virtual void PlayVolumeAdjustEarcon() override;
-  virtual void PlayPassthroughEarcon() override;
-  virtual void PlayExitScreenEarcon() override;
-  virtual void PlayEnterScreenEarcon() override;
+  void SetOutputLevel(int volume) override;
+  void SilenceSpokenFeedback() override;
+  void PlayVolumeAdjustEarcon() override;
+  void PlayPassthroughEarcon() override;
+  void PlayExitScreenEarcon() override;
+  void PlayEnterScreenEarcon() override;
 
  private:
   void UpdateTouchExplorationState();
   bool VolumeAdjustSoundEnabled();
 
   scoped_ptr<ui::TouchExplorationController> touch_exploration_controller_;
   RootWindowController* root_window_controller_;
   chromeos::CrasAudioHandler* audio_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(AshTouchExplorationManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_TOUCH_EXPLORATION_MANAGER_CHROMEOS_H_