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

ash/system/chromeos/settings/tray_settings.h

Index: ash/system/chromeos/settings/tray_settings.h
diff --git a/ash/system/chromeos/settings/tray_settings.h b/ash/system/chromeos/settings/tray_settings.h
index d54d9e5bff14237ff4f3873f0e6eb9f7b13b57de..37ece4c72a1da537cf7253a2072c4b57c5d21582 100644
--- a/ash/system/chromeos/settings/tray_settings.h
+++ b/ash/system/chromeos/settings/tray_settings.h
@@ -15,17 +15,17 @@ class SettingsDefaultView;
 class TraySettings : public SystemTrayItem {
  public:
   explicit TraySettings(SystemTray* system_tray);
-  virtual ~TraySettings();
+  ~TraySettings() override;
 
  private:
   // Overridden from SystemTrayItem
-  virtual views::View* CreateTrayView(user::LoginStatus status) override;
-  virtual views::View* CreateDefaultView(user::LoginStatus status) override;
-  virtual views::View* CreateDetailedView(user::LoginStatus status) override;
-  virtual void DestroyTrayView() override;
-  virtual void DestroyDefaultView() override;
-  virtual void DestroyDetailedView() override;
-  virtual void UpdateAfterLoginStatusChange(user::LoginStatus status) override;
+  views::View* CreateTrayView(user::LoginStatus status) override;
+  views::View* CreateDefaultView(user::LoginStatus status) override;
+  views::View* CreateDetailedView(user::LoginStatus status) override;
+  void DestroyTrayView() override;
+  void DestroyDefaultView() override;
+  void DestroyDetailedView() override;
+  void UpdateAfterLoginStatusChange(user::LoginStatus status) override;
 
   tray::SettingsDefaultView* default_view_;