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

ash/ash_touch_exploration_manager_chromeos.h

Index: ash/ash_touch_exploration_manager_chromeos.h
diff --git a/ash/ash_touch_exploration_manager_chromeos.h b/ash/ash_touch_exploration_manager_chromeos.h
index 67e8e30cf1b1f2f170f85154e6c37630107a1a41..6c9fcf4491e0da4d3eb5d5cde479eca896eb10c2 100644
--- a/ash/ash_touch_exploration_manager_chromeos.h
+++ b/ash/ash_touch_exploration_manager_chromeos.h
@@ -26,19 +26,19 @@ class ASH_EXPORT AshTouchExplorationManager
  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();