This CL replaces user_manager::UserID with AccountId.

chrome/browser/chromeos/login/existing_user_controller.h

 // Copyright (c) 2012 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_BROWSER_CHROMEOS_LOGIN_EXISTING_USER_CONTROLLER_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_EXISTING_USER_CONTROLLER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 236 matching lines @@
   // Username for public session auto-login.
   std::string public_session_auto_login_username_;
 
   // Used to execute login operations.
   scoped_ptr<LoginPerformer> login_performer_;
 
   // Delegate to forward all authentication status events to.
   // Tests can use this to receive authentication status events.
   AuthStatusConsumer* auth_status_consumer_;
 
-  // Username of the last login attempt.
-  std::string last_login_attempt_username_;
+  // AccountId of the last login attempt.
+  AccountId last_login_attempt_account_id_ = EmptyAccountId();
 
   // OOBE/login display host.
   LoginDisplayHost* host_;
 
   // Login UI implementation instance.
   scoped_ptr<LoginDisplay> login_display_;
 
   // Number of login attempts. Used to show help link when > 1 unsuccessful
   // logins for the same user.
   size_t num_login_attempts_;
@@ skipping 56 matching lines @@
 
   // Factory of callbacks.
   base::WeakPtrFactory<ExistingUserController> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExistingUserController);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_EXISTING_USER_CONTROLLER_H_