Standardize usage of virtual/override/final in content/

content/shell/renderer/layout_test/layout_test_render_frame_observer.h

 // Copyright 2013 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 CONTENT_SHELL_LAYOUT_TEST_RENDER_FRAME_OBSERVER_H_
 #define CONTENT_SHELL_LAYOUT_TEST_RENDER_FRAME_OBSERVER_H_
 
 #include "content/public/renderer/render_frame_observer.h"
 
 namespace blink {
 class WebFrame;
 }
 
 namespace content {
 class RenderFrame;
 
 class LayoutTestRenderFrameObserver : public RenderFrameObserver {
  public:
   explicit LayoutTestRenderFrameObserver(RenderFrame* render_frame);
-  virtual ~LayoutTestRenderFrameObserver() {}
+  ~LayoutTestRenderFrameObserver() override {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayoutTestRenderFrameObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_SHELL_LAYOUT_TEST_RENDER_FRAME_OBSERVER_H_