MacViews: Remove redundant virtuals in NativeWidgetMac and co.

ui/views/event_monitor_mac.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 UI_VIEWS_EVENT_MONITOR_MAC_H_
 #define UI_VIEWS_EVENT_MONITOR_MAC_H_
 
 #include "base/macros.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/views/event_monitor.h"
 
 namespace views {
 
 class EventMonitorMac : public EventMonitor {
  public:
   EventMonitorMac(ui::EventHandler* event_handler,
                   gfx::NativeWindow target_window);
-  virtual ~EventMonitorMac();
+  ~EventMonitorMac() override;
 
  private:
   id monitor_;
 
   DISALLOW_COPY_AND_ASSIGN(EventMonitorMac);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_EVENT_MONITOR_MAC_H_