Standardize usage of virtual/override/final in extensions/

extensions/renderer/extension_helper.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 EXTENSIONS_RENDERER_EXTENSION_HELPER_H_
 #define EXTENSIONS_RENDERER_EXTENSION_HELPER_H_
 
 #include <vector>
 
 #include "content/public/common/console_message_level.h"
@@ skipping 25 matching lines @@
   static std::vector<content::RenderView*> GetExtensionViews(
       const std::string& extension_id,
       int browser_window_id,
       ViewType view_type);
 
   // Returns the given extension's background page, or NULL if none.
   static content::RenderView* GetBackgroundPage(
       const std::string& extension_id);
 
   ExtensionHelper(content::RenderView* render_view, Dispatcher* dispatcher);
-  virtual ~ExtensionHelper();
+  ~ExtensionHelper() override;
 
   int tab_id() const { return tab_id_; }
   int browser_window_id() const { return browser_window_id_; }
   ViewType view_type() const { return view_type_; }
   Dispatcher* dispatcher() const { return dispatcher_; }
 
  private:
   // RenderViewObserver implementation.
-  virtual bool OnMessageReceived(const IPC::Message& message) override;
-  virtual void DidCreateDocumentElement(blink::WebLocalFrame* frame) override;
-  virtual void DidMatchCSS(
+  bool OnMessageReceived(const IPC::Message& message) override;
+  void DidCreateDocumentElement(blink::WebLocalFrame* frame) override;
+  void DidMatchCSS(
       blink::WebLocalFrame* frame,
       const blink::WebVector<blink::WebString>& newly_matching_selectors,
       const blink::WebVector<blink::WebString>& stopped_matching_selectors)
       override;
-  virtual void DraggableRegionsChanged(blink::WebFrame* frame) override;
+  void DraggableRegionsChanged(blink::WebFrame* frame) override;
 
   void OnExtensionResponse(int request_id, bool success,
                            const base::ListValue& response,
                            const std::string& error);
   void OnExtensionMessageInvoke(const std::string& extension_id,
                                 const std::string& module_name,
                                 const std::string& function_name,
                                 const base::ListValue& args,
                                 bool user_gesture);
   void OnExtensionDispatchOnConnect(
@@ skipping 24 matching lines @@
 
   // Id number of browser window which RenderView is attached to.
   int browser_window_id_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionHelper);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_EXTENSION_HELPER_H_