Standardize usage of virtual/override/final in chrome/

chrome/common/extensions/manifest_handlers/app_isolation_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 CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLERS_APP_ISOLATION_INFO_H_
 #define CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLERS_APP_ISOLATION_INFO_H_
 
 #include <string>
 #include <vector>
 
 #include "extensions/common/extension.h"
 #include "extensions/common/manifest.h"
 #include "extensions/common/manifest_handler.h"
 
 namespace extensions {
 
 struct AppIsolationInfo : public Extension::ManifestData {
   explicit AppIsolationInfo(bool isolated_storage);
-  virtual ~AppIsolationInfo();
+  ~AppIsolationInfo() override;
 
   static bool HasIsolatedStorage(const Extension* extension);
 
   // Whether this extension requests isolated storage.
   bool has_isolated_storage;
 };
 
 // Parses the "isolation" manifest key.
 class AppIsolationHandler : public ManifestHandler {
  public:
   AppIsolationHandler();
-  virtual ~AppIsolationHandler();
+  ~AppIsolationHandler() 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(AppIsolationHandler);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLERS_APP_ISOLATION_INFO_H_