MacViews: Remove redundant virtuals in NativeWidgetMac and co.

ui/views/widget/native_widget_mac_interactive_uitest.mm

 // 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.
 
 #include "ui/views/widget/native_widget_mac.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "ui/views/test/widget_test.h"
 #include "ui/views/test/test_widget_observer.h"
@@ skipping 24 matching lines @@
 
  private:
   DISALLOW_COPY_AND_ASSIGN(NativeWidgetMacInteractiveUITest);
 };
 
 class NativeWidgetMacInteractiveUITest::Observer : public TestWidgetObserver {
  public:
   Observer(NativeWidgetMacInteractiveUITest* parent, Widget* widget)
       : TestWidgetObserver(widget), parent_(parent) {}
 
-  virtual void OnWidgetActivationChanged(Widget* widget, bool active) override {
+  void OnWidgetActivationChanged(Widget* widget, bool active) override {
     if (active)
       parent_->activationCount_++;
     else
       parent_->deactivationCount_++;
   }
 
  private:
   NativeWidgetMacInteractiveUITest* parent_;
 
   DISALLOW_COPY_AND_ASSIGN(Observer);
@@ skipping 72 matching lines @@
   widget2->CloseNow();
   widget->CloseNow();
 }
 
 INSTANTIATE_TEST_CASE_P(NativeWidgetMacInteractiveUITestInstance,
                         NativeWidgetMacInteractiveUITest,
                         ::testing::Bool());
 
 }  // namespace test
 }  // namespace views