Standardize usage of virtual/override/final in ui/

ui/message_center/message_center_tray.cc

Index: ui/message_center/message_center_tray.cc
diff --git a/ui/message_center/message_center_tray.cc b/ui/message_center/message_center_tray.cc
index 3037c6990a6809654c06162bf5511e6a1b929d0b..a4fbb0895b1b4760495f27123eb890d3e261a4b4 100644
--- a/ui/message_center/message_center_tray.cc
+++ b/ui/message_center/message_center_tray.cc
@@ -29,15 +29,14 @@ class NotificationMenuModel : public ui::SimpleMenuModel,
   NotificationMenuModel(MessageCenterTray* tray,
                         const NotifierId& notifier_id,
                         const base::string16& display_source);
-  virtual ~NotificationMenuModel();
+  ~NotificationMenuModel() override;
 
   // Overridden from ui::SimpleMenuModel::Delegate:
-  virtual bool IsCommandIdChecked(int command_id) const override;
-  virtual bool IsCommandIdEnabled(int command_id) const override;
-  virtual bool GetAcceleratorForCommandId(
-      int command_id,
-      ui::Accelerator* accelerator) override;
-  virtual void ExecuteCommand(int command_id, int event_flags) override;
+  bool IsCommandIdChecked(int command_id) const override;
+  bool IsCommandIdEnabled(int command_id) const override;
+  bool GetAcceleratorForCommandId(int command_id,
+                                  ui::Accelerator* accelerator) override;
+  void ExecuteCommand(int command_id, int event_flags) override;
 
  private:
   MessageCenterTray* tray_;