Remove unnecessary 'virtual' annotation from mojo

mojo/services/html_viewer/webthemeengine_impl.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 MOJO_SERVICES_HTML_VIEWER_WEBTHEMEENGINE_IMPL_H_
 #define MOJO_SERVICES_HTML_VIEWER_WEBTHEMEENGINE_IMPL_H_
 
 #include "third_party/WebKit/public/platform/WebThemeEngine.h"
 
 namespace html_viewer {
 
 class WebThemeEngineImpl : public blink::WebThemeEngine {
  public:
   // WebThemeEngine methods:
-  virtual blink::WebSize getSize(blink::WebThemeEngine::Part);
-  virtual void paint(
-      blink::WebCanvas* canvas,
-      blink::WebThemeEngine::Part part,
-      blink::WebThemeEngine::State state,
-      const blink::WebRect& rect,
-      const blink::WebThemeEngine::ExtraParams* extra_params);
+  blink::WebSize getSize(blink::WebThemeEngine::Part) override;
+  void paint(blink::WebCanvas* canvas,
+             blink::WebThemeEngine::Part part,
+             blink::WebThemeEngine::State state,
+             const blink::WebRect& rect,
+             const blink::WebThemeEngine::ExtraParams* extra_params) override;
   virtual void paintStateTransition(blink::WebCanvas* canvas,
                                     blink::WebThemeEngine::Part part,
                                     blink::WebThemeEngine::State startState,
                                     blink::WebThemeEngine::State endState,
                                     double progress,
                                     const blink::WebRect& rect);
 };
 
 }  // namespace html_viewer
 
 #endif  // MOJO_SERVICES_HTML_VIEWER_WEBTHEMEENGINE_IMPL_H_