Standardize usage of virtual/override/final in extensions/

extensions/common/manifest_handlers/incognito_info.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 EXTENSIONS_COMMON_MANIFEST_HANDLERS_INCOGNITO_INFO_H_
 #define EXTENSIONS_COMMON_MANIFEST_HANDLERS_INCOGNITO_INFO_H_
 
 #include "base/strings/string16.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/manifest_handler.h"
 
 namespace extensions {
 
 struct IncognitoInfo : public Extension::ManifestData {
   explicit IncognitoInfo(bool split_mode);
-  virtual ~IncognitoInfo();
+  ~IncognitoInfo() override;
 
   // If true, a separate process will be used for the extension in incognito
   // mode.
   bool split_mode;
 
   // Return the incognito mode information for the given |extension|.
   static bool IsSplitMode(const Extension* extension);
 };
 
 // Parses the "incognito" manifest key.
 class IncognitoHandler : public ManifestHandler {
  public:
   IncognitoHandler();
-  virtual ~IncognitoHandler();
+  ~IncognitoHandler() override;
 
-  virtual bool Parse(Extension* extension, base::string16* error) override;
-  virtual bool AlwaysParseForType(Manifest::Type type) const override;
+  bool Parse(Extension* extension, base::string16* error) override;
+  bool AlwaysParseForType(Manifest::Type type) const override;
 
  private:
-  virtual const std::vector<std::string> Keys() const override;
+  const std::vector<std::string> Keys() const override;
 
   DISALLOW_COPY_AND_ASSIGN(IncognitoHandler);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_MANIFEST_HANDLERS_INCOGNITO_INFO_H_