Standardize usage of virtual/override/final specifiers.

extensions/shell/browser/api/shell_identity/shell_identity_api.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_SHELL_BROWSER_API_SHELL_IDENTITY_SHELL_IDENTITY_API_H_
 #define EXTENSIONS_SHELL_BROWSER_API_SHELL_IDENTITY_SHELL_IDENTITY_API_H_
 
 #include "base/macros.h"
 #include "extensions/browser/extension_function.h"
 
 namespace extensions {
 
 // TODO(jamescook): Implement this function.
 class ShellIdentityGetAuthTokenFunction : public UIThreadExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("shell.identity.getAuthToken", UNKNOWN);
 
   ShellIdentityGetAuthTokenFunction();
 
  protected:
-  virtual ~ShellIdentityGetAuthTokenFunction();
+  ~ShellIdentityGetAuthTokenFunction() override;
 
   // ExtensionFunction:
-  virtual ResponseAction Run() override;
+  ResponseAction Run() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ShellIdentityGetAuthTokenFunction);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_SHELL_BROWSER_API_SHELL_IDENTITY_SHELL_IDENTITY_API_H_