We should use UserID object to identify users instead of username.

chrome/browser/chromeos/login/users/chrome_user_manager_impl.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 CHROME_BROWSER_CHROMEOS_LOGIN_USERS_CHROME_USER_MANAGER_IMPL_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_USERS_CHROME_USER_MANAGER_IMPL_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 50 matching lines @@
 
   // Creates ChromeUserManagerImpl instance.
   static scoped_ptr<ChromeUserManager> CreateChromeUserManager();
 
   // Registers user manager preferences.
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
   // UserManagerInterface implementation:
   BootstrapManager* GetBootstrapManager() override;
   MultiProfileUserController* GetMultiProfileUserController() override;
-  UserImageManager* GetUserImageManager(const std::string& user_id) override;
+  UserImageManager* GetUserImageManager(const user_manager::UserID& user_id) override;
   SupervisedUserManager* GetSupervisedUserManager() override;
   UserFlow* GetCurrentUserFlow() const override;
-  UserFlow* GetUserFlow(const std::string& user_id) const override;
-  void SetUserFlow(const std::string& user_id, UserFlow* flow) override;
-  void ResetUserFlow(const std::string& user_id) override;
+  UserFlow* GetUserFlow(const user_manager::UserID& user_id) const override;
+  void SetUserFlow(const user_manager::UserID& user_id, UserFlow* flow) override;
+  void ResetUserFlow(const user_manager::UserID& user_id) override;
 
   // UserManager implementation:
   void Shutdown() override;
   user_manager::UserList GetUsersAllowedForMultiProfile() const override;
   user_manager::UserList GetUsersAllowedForSupervisedUsersCreation()
       const override;
   user_manager::UserList GetUnlockUsers() const override;
   void SessionStarted() override;
   void SaveUserOAuthStatus(
-      const std::string& user_id,
+      const user_manager::UserID& user_id,
       user_manager::User::OAuthTokenStatus oauth_token_status) override;
-  void SaveUserDisplayName(const std::string& user_id,
+  void SaveUserDisplayName(const user_manager::UserID& user_id,
                            const base::string16& display_name) override;
   bool CanCurrentUserLock() const override;
   bool IsUserNonCryptohomeDataEphemeral(
-      const std::string& user_id) const override;
+      const user_manager::UserID& user_id) const override;
   bool AreSupervisedUsersAllowed() const override;
 
   // content::NotificationObserver implementation.
   void Observe(int type,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
   // policy::CloudExternalDataPolicyObserver::Delegate:
   void OnExternalDataSet(const std::string& policy,
-                         const std::string& user_id) override;
+                         const user_manager::UserID& user_id) override;
   void OnExternalDataCleared(const std::string& policy,
-                             const std::string& user_id) override;
+                             const user_manager::UserID& user_id) override;
   void OnExternalDataFetched(const std::string& policy,
-                             const std::string& user_id,
+                             const user_manager::UserID& user_id,
                              scoped_ptr<std::string> data) override;
 
   // policy::DeviceLocalAccountPolicyService::Observer implementation.
-  void OnPolicyUpdated(const std::string& user_id) override;
+  void OnPolicyUpdated(const user_manager::UserID& user_id) override;
   void OnDeviceLocalAccountsChanged() override;
 
   void StopPolicyObserverForTesting();
 
   // UserManagerBase implementation:
   bool AreEphemeralUsersEnabled() const override;
 
  protected:
   const std::string& GetApplicationLocale() const override;
   PrefService* GetLocalState() const override;
   void HandleUserOAuthTokenStatusChange(
-      const std::string& user_id,
+      const user_manager::UserID& user_id,
       user_manager::User::OAuthTokenStatus status) const override;
   bool IsEnterpriseManaged() const override;
   void LoadPublicAccounts(std::set<std::string>* users_set) override;
   void NotifyOnLogin() override;
   void NotifyUserAddedToSession(const user_manager::User* added_user,
                                 bool user_switch_pending) override;
   void PerformPreUserListLoadingActions() override;
   void PerformPostUserListLoadingActions() override;
   void PerformPostUserLoggedInActions(bool browser_restart) override;
-  void RemoveNonCryptohomeData(const std::string& user_id) override;
-  void RemoveUserInternal(const std::string& user_email,
+  void RemoveNonCryptohomeData(const user_manager::UserID& user_id) override;
+  void RemoveUserInternal(const user_manager::UserID& user_id,
                           user_manager::RemoveUserDelegate* delegate) override;
-  bool IsDemoApp(const std::string& user_id) const override;
-  bool IsKioskApp(const std::string& user_id) const override;
+  bool IsDemoApp(const user_manager::UserID& user_id) const override;
+  bool IsKioskApp(const user_manager::UserID& user_id) const override;
   bool IsPublicAccountMarkedForRemoval(
-      const std::string& user_id) const override;
+      const user_manager::UserID& user_id) const override;
   void DemoAccountLoggedIn() override;
   void GuestUserLoggedIn() override;
   void KioskAppLoggedIn(const std::string& app_id) override;
   void PublicAccountUserLoggedIn(user_manager::User* user) override;
-  void RegularUserLoggedIn(const std::string& user_id) override;
-  void RegularUserLoggedInAsEphemeral(const std::string& user_id) override;
-  void SupervisedUserLoggedIn(const std::string& user_id) override;
-  bool HasPendingBootstrap(const std::string& user_id) const override;
+  void RegularUserLoggedIn(const user_manager::UserID& user_id) override;
+  void RegularUserLoggedInAsEphemeral(const user_manager::UserID& user_id) override;
+  void SupervisedUserLoggedIn(const user_manager::UserID& user_id) override;
+  bool HasPendingBootstrap(const user_manager::UserID& user_id) const override;
 
  private:
   friend class SupervisedUserManagerImpl;
   friend class UserManagerTest;
   friend class WallpaperManager;
   friend class WallpaperManagerTest;
 
-  typedef base::hash_map<std::string, linked_ptr<UserImageManager> >
+  typedef base::hash_map<user_manager::UserID, linked_ptr<UserImageManager> >
       UserImageManagerMap;
 
   ChromeUserManagerImpl();
 
   // Retrieves trusted device policies and removes users from the persistent
   // list if ephemeral users are enabled. Schedules a callback to itself if
   // trusted device policies are not yet available.
   void RetrieveTrustedDevicePolicies();
 
   // Updates current user ownership on UI thread.
   void UpdateOwnership();
 
   // If data for a public account is marked as pending removal and the user is
   // no longer logged into that account, removes the data.
   void CleanUpPublicAccountNonCryptohomeDataPendingRemoval();
 
   // Removes data belonging to public accounts that are no longer found on the
   // user list. If the user is currently logged into one of these accounts, the
   // data for that account is not removed immediately but marked as pending
   // removal after logout.
   void CleanUpPublicAccountNonCryptohomeData(
-      const std::vector<std::string>& old_public_accounts);
+      const std::vector<user_manager::UserID>& old_public_accounts);
 
   // Replaces the list of public accounts with those found in
   // |device_local_accounts|. Ensures that data belonging to accounts no longer
   // on the list is removed. Returns |true| if the list has changed.
   // Public accounts are defined by policy. This method is called whenever an
   // updated list of public accounts is received from policy.
   bool UpdateAndCleanUpPublicAccounts(
       const std::vector<policy::DeviceLocalAccount>& device_local_accounts);
 
   // Updates the display name for public account |username| from policy settings
   // associated with that username.
-  void UpdatePublicAccountDisplayName(const std::string& user_id);
+  void UpdatePublicAccountDisplayName(const user_manager::UserID& user_id);
 
   // Notifies the UI about a change to the user list.
   void NotifyUserListChanged();
 
   // Lazily creates default user flow.
   UserFlow* GetDefaultUserFlow() const;
 
   // MultiProfileUserControllerDelegate implementation:
-  void OnUserNotAllowed(const std::string& user_email) override;
+  void OnUserNotAllowed(const user_manager::UserID& user_id) override;
 
   // BootstrapManager::Delegate implementation:
-  void RemovePendingBootstrapUser(const std::string& user_id) override;
+  void RemovePendingBootstrapUser(const user_manager::UserID& user_id) override;
 
   // Update the number of users.
   void UpdateNumberOfUsers();
 
   // Starts (or stops) automatic timezone refresh on geolocation,
   // depending on user preferences.
   void UpdateUserTimeZoneRefresher(Profile* profile);
 
   // Interface to the signed settings store.
   CrosSettings* cros_settings_;
 
   // Interface to device-local account definitions and associated policy.
   policy::DeviceLocalAccountPolicyService* device_local_account_policy_service_;
 
   content::NotificationRegistrar registrar_;
 
   // User avatar managers.
   UserImageManagerMap user_image_managers_;
 
   // Supervised user manager.
   scoped_ptr<SupervisedUserManagerImpl> supervised_user_manager_;
 
   // Session length limiter.
   scoped_ptr<SessionLengthLimiter> session_length_limiter_;
 
-  typedef std::map<std::string, UserFlow*> FlowMap;
+  typedef std::map<user_manager::UserID, UserFlow*> FlowMap;
 
   // Lazy-initialized default flow.
   mutable scoped_ptr<UserFlow> default_flow_;
 
-  // Specific flows by user e-mail. Keys should be canonicalized before
-  // access.
+  // Specific flows by user id.
   FlowMap specific_flows_;
 
   scoped_ptr<CrosSettings::ObserverSubscription> local_accounts_subscription_;
 
   scoped_ptr<MultiProfileUserController> multi_profile_user_controller_;
 
   // Observer for the policy that can be used to manage user images.
   scoped_ptr<policy::CloudExternalDataPolicyObserver> avatar_policy_observer_;
 
   // Observer for the policy that can be used to manage wallpapers.
   scoped_ptr<policy::CloudExternalDataPolicyObserver>
       wallpaper_policy_observer_;
 
   scoped_ptr<BootstrapManager> bootstrap_manager_;
 
   base::WeakPtrFactory<ChromeUserManagerImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeUserManagerImpl);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_USERS_CHROME_USER_MANAGER_IMPL_H_