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

chrome/browser/ui/ash/session_state_delegate_chromeos.cc

 // 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.
 
 #include "chrome/browser/ui/ash/session_state_delegate_chromeos.h"
 
 #include "ash/multi_profile_uma.h"
 #include "ash/session/session_state_observer.h"
 #include "ash/system/chromeos/multi_user/user_switch_util.h"
 #include "base/bind.h"
@@ skipping 45 matching lines @@
   DCHECK_LT(index, NumberOfLoggedInUsers());
   user_manager::User* user =
       user_manager::UserManager::Get()->GetLRULoggedInUsers()[index];
   CHECK(user);
   return chromeos::ProfileHelper::Get()->GetProfileByUserUnsafe(user);
 }
 
 content::BrowserContext*
 SessionStateDelegateChromeos::GetBrowserContextForWindow(
     aura::Window* window) {
-  const std::string& user_id =
+  const user_manager::UserID& user_id =
       chrome::MultiUserWindowManager::GetInstance()->GetWindowOwner(window);
   return user_id.empty() ? NULL
                          : multi_user_util::GetProfileFromUserID(user_id);
 }
 
 content::BrowserContext*
 SessionStateDelegateChromeos::GetUserPresentingBrowserContextForWindow(
     aura::Window* window) {
-  const std::string& user_id =
+  const user_manager::UserID& user_id =
       chrome::MultiUserWindowManager::GetInstance()->GetUserPresentingWindow(
           window);
   return user_id.empty() ? NULL
                          : multi_user_util::GetProfileFromUserID(user_id);
 }
 
 int SessionStateDelegateChromeos::GetMaximumNumberOfLoggedInUsers() const {
   // We limit list of logged in users to 10 due to memory constraints.
   // Note that 10 seems excessive, but we want to test how many users are
   // actually added to a session.
@@ skipping 88 matching lines @@
       Profile::FromBrowserContext(context));
 }
 
 bool SessionStateDelegateChromeos::ShouldShowAvatar(
     aura::Window* window) const {
   return chrome::MultiUserWindowManager::GetInstance()->
       ShouldShowAvatar(window);
 }
 
 void SessionStateDelegateChromeos::SwitchActiveUser(
-    const std::string& user_id) {
+    const user_manager::UserID& user_id) {
   // Disallow switching to an already active user since that might crash.
   // Also check that we got a user id and not an email address.
-  DCHECK_EQ(user_id,
-            gaia::CanonicalizeEmail(gaia::SanitizeEmail(user_id)));
-  if (user_id == user_manager::UserManager::Get()->GetActiveUser()->email())
+  DCHECK_EQ(user_id.GetUserEmail(),
+            gaia::CanonicalizeEmail(gaia::SanitizeEmail(user_id.GetUserEmail())));
+  if (user_id == user_manager::UserManager::Get()->GetActiveUser()->GetUserID())
     return;
   TryToSwitchUser(user_id);
 }
 
 void SessionStateDelegateChromeos::CycleActiveUser(CycleUser cycle_user) {
   // Make sure there is a user to switch to.
   if (NumberOfLoggedInUsers() <= 1)
     return;
 
   const user_manager::UserList& logged_in_users =
       user_manager::UserManager::Get()->GetLoggedInUsers();
 
-  std::string user_id =
-      user_manager::UserManager::Get()->GetActiveUser()->email();
+  user_manager::UserID user_id =
+      user_manager::UserManager::Get()->GetActiveUser()->GetUserID();
 
   // Get an iterator positioned at the active user.
   user_manager::UserList::const_iterator it;
   for (it = logged_in_users.begin();
        it != logged_in_users.end(); ++it) {
-    if ((*it)->email() == user_id)
+    if ((*it)->GetUserID() == user_id)
       break;
   }
 
   // Active user not found.
   if (it == logged_in_users.end())
     return;
 
   // Get the user's email to select, wrapping to the start/end of the list if
   // necessary.
   switch (cycle_user) {
     case CYCLE_TO_NEXT_USER:
       if (++it == logged_in_users.end())
-        user_id = (*logged_in_users.begin())->email();
+        user_id = (*logged_in_users.begin())->GetUserID();
       else
-        user_id = (*it)->email();
+        user_id = (*it)->GetUserID();
       break;
     case CYCLE_TO_PREVIOUS_USER:
       if (it == logged_in_users.begin())
         it = logged_in_users.end();
-      user_id = (*(--it))->email();
+      user_id = (*(--it))->GetUserID();
       break;
   }
 
   // Switch using the transformed |user_id|.
   TryToSwitchUser(user_id);
 }
 
 bool SessionStateDelegateChromeos::IsMultiProfileAllowedByPrimaryUserPolicy()
     const {
   return chromeos::MultiProfileUserController::GetPrimaryUserPolicy() ==
@@ skipping 12 matching lines @@
 
 void SessionStateDelegateChromeos::LoggedInStateChanged() {
   SetSessionState(chromeos::LoginState::Get()->IsUserLoggedIn() ?
       SESSION_STATE_ACTIVE : SESSION_STATE_LOGIN_PRIMARY, false);
 }
 
 void SessionStateDelegateChromeos::ActiveUserChanged(
     const user_manager::User* active_user) {
   FOR_EACH_OBSERVER(ash::SessionStateObserver,
                     session_state_observer_list_,
-                    ActiveUserChanged(active_user->email()));
+                    ActiveUserChanged(active_user->GetUserID()));
 }
 
 void SessionStateDelegateChromeos::UserAddedToSession(
     const user_manager::User* added_user) {
   FOR_EACH_OBSERVER(ash::SessionStateObserver,
                     session_state_observer_list_,
-                    UserAddedToSession(added_user->email()));
+                    UserAddedToSession(added_user->GetUserID()));
 }
 
 void SessionStateDelegateChromeos::OnUserAddingStarted() {
   SetSessionState(SESSION_STATE_LOGIN_SECONDARY, false);
 }
 
 void SessionStateDelegateChromeos::OnUserAddingFinished() {
   SetSessionState(SESSION_STATE_ACTIVE, false);
 }
 
 void SessionStateDelegateChromeos::SetSessionState(SessionState new_state,
                                                    bool force) {
   if (session_state_ == new_state && !force)
     return;
 
   session_state_ = new_state;
   NotifySessionStateChanged();
 }
 
 void SessionStateDelegateChromeos::NotifySessionStateChanged() {
   FOR_EACH_OBSERVER(ash::SessionStateObserver,
                     session_state_observer_list_,
                     SessionStateChanged(session_state_));
 }
 
-void DoSwitchUser(const std::string& user_id) {
+void DoSwitchUser(const user_manager::UserID& user_id) {
   user_manager::UserManager::Get()->SwitchActiveUser(user_id);
 }
 
 void SessionStateDelegateChromeos::TryToSwitchUser(
-    const std::string& user_id) {
+    const user_manager::UserID& user_id) {
   ash::TrySwitchingActiveUser(base::Bind(&DoSwitchUser, user_id));
 }