Fix virtual/override/final usage in Source/modules/.

Source/modules/screen_orientation/ScreenOrientationDispatcher.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 ScreenOrientationDispatcher_h
 #define ScreenOrientationDispatcher_h
 
 #include "core/frame/PlatformEventDispatcher.h"
 #include "platform/heap/Handle.h"
 
@@ skipping 11 matching lines @@
     USING_GARBAGE_COLLECTED_MIXIN(ScreenOrientationDispatcher);
 public:
     static ScreenOrientationDispatcher& instance();
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     ScreenOrientationDispatcher();
 
     // Inherited from PlatformEventDispatcher.
-    virtual void startListening() override;
-    virtual void stopListening() override;
+    void startListening() override;
+    void stopListening() override;
 };
 
 } // namespace blink
 
 #endif // ScreenOrientationDispatcher_h