Standardize usage of virtual/override/final in extensions/

extensions/common/manifest_handlers/web_accessible_resources_info.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_COMMON_MANIFEST_HANDLERS_WEB_ACCESSIBLE_RESOURCES_INFO_H_
 #define EXTENSIONS_COMMON_MANIFEST_HANDLERS_WEB_ACCESSIBLE_RESOURCES_INFO_H_
 
 #include <string>
 
 #include "extensions/common/extension.h"
 #include "extensions/common/manifest_handler.h"
 
 namespace extensions {
 
 // A structure to hold the web accessible extension resources
 // that may be specified in the manifest of an extension using
 // "web_accessible_resources" key.
 struct WebAccessibleResourcesInfo : public Extension::ManifestData {
   // Define out of line constructor/destructor to please Clang.
   WebAccessibleResourcesInfo();
-  virtual ~WebAccessibleResourcesInfo();
+  ~WebAccessibleResourcesInfo() override;
 
   // Returns true if the specified resource is web accessible.
   static bool IsResourceWebAccessible(const Extension* extension,
                                       const std::string& relative_path);
 
   // Returns true when 'web_accessible_resources' are defined for the extension.
   static bool HasWebAccessibleResources(const Extension* extension);
 
   // Optional list of web accessible extension resources.
   URLPatternSet web_accessible_resources_;
 };
 
 // Parses the "web_accessible_resources" manifest key.
 class WebAccessibleResourcesHandler : public ManifestHandler {
  public:
   WebAccessibleResourcesHandler();
-  virtual ~WebAccessibleResourcesHandler();
+  ~WebAccessibleResourcesHandler() override;
 
-  virtual bool Parse(Extension* extension, base::string16* error) override;
+  bool Parse(Extension* extension, base::string16* error) override;
 
  private:
-  virtual const std::vector<std::string> Keys() const override;
+  const std::vector<std::string> Keys() const override;
 
   DISALLOW_COPY_AND_ASSIGN(WebAccessibleResourcesHandler);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_MANIFEST_HANDLERS_WEB_ACCESSIBLE_RESOURCES_INFO_H_