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

chrome/browser/chromeos/login/ui/webui_login_display.cc

 // 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.
 
 #include "chrome/browser/chromeos/login/ui/webui_login_display.h"
 
 #include "chrome/browser/chromeos/accessibility/accessibility_manager.h"
 #include "chrome/browser/chromeos/login/lock/screen_locker.h"
 #include "chrome/browser/chromeos/login/screens/chrome_user_selection_screen.h"
 #include "chrome/browser/chromeos/login/signin_screen_controller.h"
@@ skipping 62 matching lines @@
 // ---- User selection screen methods
 
 void WebUILoginDisplay::HandleGetUsers() {
   SignInScreenController::Get()->SendUserList();
 }
 
 const user_manager::UserList& WebUILoginDisplay::GetUsers() const {
   return SignInScreenController::Get()->GetUsers();
 }
 
-void WebUILoginDisplay::CheckUserStatus(const std::string& user_id) {
+void WebUILoginDisplay::CheckUserStatus(const user_manager::UserID& user_id) {
   SignInScreenController::Get()->CheckUserStatus(user_id);
 }
 
 // ---- Gaia screen methods
 
 // ---- Not yet classified methods
 
 void WebUILoginDisplay::OnPreferencesChanged() {
   if (webui_handler_)
     webui_handler_->OnPreferencesChanged();
@@ skipping 79 matching lines @@
                             help_topic_id);
 }
 
 void WebUILoginDisplay::ShowErrorScreen(LoginDisplay::SigninError error_id) {
   VLOG(1) << "Show error screen, error_id: " << error_id;
   if (!webui_handler_)
     return;
   webui_handler_->ShowErrorScreen(error_id);
 }
 
-void WebUILoginDisplay::ShowGaiaPasswordChanged(const std::string& username) {
+void WebUILoginDisplay::ShowGaiaPasswordChanged(const user_manager::UserID& user_id) {
   if (webui_handler_)
-    webui_handler_->ShowGaiaPasswordChanged(username);
+    webui_handler_->ShowGaiaPasswordChanged(user_id);
 }
 
 void WebUILoginDisplay::ShowPasswordChangedDialog(bool show_password_error,
-                                                  const std::string& email) {
+                                                  const user_manager::UserID& user_id) {
   if (webui_handler_)
-    webui_handler_->ShowPasswordChangedDialog(show_password_error, email);
+    webui_handler_->ShowPasswordChangedDialog(show_password_error, user_id);
 }
 
-void WebUILoginDisplay::ShowSigninUI(const std::string& email) {
+void WebUILoginDisplay::ShowSigninUI(const user_manager::UserID& user_id) {
   if (webui_handler_)
-    webui_handler_->ShowSigninUI(email);
+    webui_handler_->ShowSigninUI(user_id);
 }
 
 void WebUILoginDisplay::ShowWhitelistCheckFailedError() {
   if (webui_handler_)
     webui_handler_->ShowWhitelistCheckFailedError();
 }
 
 // WebUILoginDisplay, NativeWindowDelegate implementation: ---------------------
 gfx::NativeWindow WebUILoginDisplay::GetNativeWindow() const {
   return parent_window();
@@ skipping 32 matching lines @@
   if (delegate_)
     delegate_->Login(user_context, specifics);
 }
 
 void WebUILoginDisplay::MigrateUserData(const std::string& old_password) {
   DCHECK(delegate_);
   if (delegate_)
     delegate_->MigrateUserData(old_password);
 }
 
-void WebUILoginDisplay::LoadWallpaper(const std::string& username) {
-  WallpaperManager::Get()->SetUserWallpaperDelayed(username);
+void WebUILoginDisplay::LoadWallpaper(const user_manager::UserID& user_id) {
+  WallpaperManager::Get()->SetUserWallpaperDelayed(user_id);
 }
 
 void WebUILoginDisplay::LoadSigninWallpaper() {
   WallpaperManager::Get()->SetDefaultWallpaperDelayed(
-      chromeos::login::kSignInUser);
+      chromeos::login::GetSignInUserID());
 }
 
 void WebUILoginDisplay::OnSigninScreenReady() {
   SignInScreenController::Get()->OnSigninScreenReady();
 
   if (delegate_)
     delegate_->OnSigninScreenReady();
 }
 
-void WebUILoginDisplay::RemoveUser(const std::string& user_id) {
+void WebUILoginDisplay::RemoveUser(const user_manager::UserID& user_id) {
   SignInScreenController::Get()->RemoveUser(user_id);
 }
 
 void WebUILoginDisplay::ResyncUserData() {
   DCHECK(delegate_);
   if (delegate_)
     delegate_->ResyncUserData();
 }
 
 void WebUILoginDisplay::ShowEnterpriseEnrollmentScreen() {
@@ skipping 21 matching lines @@
     delegate_->ShowWrongHWIDScreen();
 }
 
 void WebUILoginDisplay::SetWebUIHandler(
     LoginDisplayWebUIHandler* webui_handler) {
   webui_handler_ = webui_handler;
   SignInScreenController::Get()->SetWebUIHandler(webui_handler_);
 }
 
 void WebUILoginDisplay::ShowSigninScreenForCreds(
-    const std::string& username,
+    const user_manager::UserID& user_id,
     const std::string& password) {
   if (webui_handler_)
-    webui_handler_->ShowSigninScreenForCreds(username, password);
+    webui_handler_->ShowSigninScreenForCreds(user_id, password);
 }
 
 bool WebUILoginDisplay::IsShowGuest() const {
   return show_guest_;
 }
 
 bool WebUILoginDisplay::IsShowUsers() const {
   return show_users_;
 }
 
@@ skipping 14 matching lines @@
   delegate_->Signout();
 }
 
 void WebUILoginDisplay::OnUserActivity(const ui::Event* event) {
   if (delegate_)
     delegate_->ResetPublicSessionAutoLoginTimer();
 }
 
 
 }  // namespace chromeos