Standardize usage of virtual/override/final in chrome/

chrome/common/extensions/manifest_handlers/theme_handler.h

 // Copyright (c) 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 CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLERS_THEME_HANDLER_H_
 #define CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLERS_THEME_HANDLER_H_
 
 #include "extensions/common/extension.h"
 #include "extensions/common/manifest_handler.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace extensions {
 
 // A structure to hold the parsed theme data.
 struct ThemeInfo : public Extension::ManifestData {
   // Define out of line constructor/destructor to please Clang.
   ThemeInfo();
-  virtual ~ThemeInfo();
+  ~ThemeInfo() override;
 
   static const base::DictionaryValue* GetImages(const Extension* extension);
   static const base::DictionaryValue* GetColors(const Extension* extension);
   static const base::DictionaryValue* GetTints(const Extension* extension);
   static const base::DictionaryValue* GetDisplayProperties(
       const Extension* extension);
 
   // A map of resource id's to relative file paths.
   scoped_ptr<base::DictionaryValue> theme_images_;
 
   // A map of color names to colors.
   scoped_ptr<base::DictionaryValue> theme_colors_;
 
   // A map of color names to colors.
   scoped_ptr<base::DictionaryValue> theme_tints_;
 
   // A map of display properties.
   scoped_ptr<base::DictionaryValue> theme_display_properties_;
 };
 
 // Parses the "theme" manifest key.
 class ThemeHandler : public ManifestHandler {
  public:
   ThemeHandler();
-  virtual ~ThemeHandler();
+  ~ThemeHandler() override;
 
-  virtual bool Parse(Extension* extension, base::string16* error) override;
-  virtual bool Validate(const Extension* extension,
-                        std::string* error,
-                        std::vector<InstallWarning>* warnings) const override;
+  bool Parse(Extension* extension, base::string16* error) override;
+  bool Validate(const Extension* extension,
+                std::string* error,
+                std::vector<InstallWarning>* warnings) const override;
 
  private:
-  virtual const std::vector<std::string> Keys() const override;
+  const std::vector<std::string> Keys() const override;
 
   DISALLOW_COPY_AND_ASSIGN(ThemeHandler);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLERS_THEME_HANDLER_H_