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

chrome/browser/ui/ash/user_accounts_delegate_chromeos.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/ui/ash/user_accounts_delegate_chromeos.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/logging.h"
 #include "chrome/browser/chromeos/profiles/profile_helper.h"
 #include "chrome/browser/chromeos/ui/inline_login_dialog.h"
 #include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
 #include "chrome/browser/signin/signin_manager_factory.h"
 #include "components/signin/core/browser/mutable_profile_oauth2_token_service.h"
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
 #include "components/signin/core/browser/signin_manager.h"
 #include "components/user_manager/user.h"
+#include "components/user_manager/user_id.h"
 #include "google_apis/gaia/gaia_auth_util.h"
 
 namespace chromeos {
 
 UserAccountsDelegateChromeOS::UserAccountsDelegateChromeOS(
     Profile* user_profile)
     : user_profile_(user_profile) {
   ProfileOAuth2TokenServiceFactory::GetForProfile(user_profile_)
       ->AddObserver(this);
 }
@@ skipping 20 matching lines @@
       << "Found " << std::distance(it, accounts.end())
       << " primary accounts in the account list.";
   accounts.erase(it, accounts.end());
   return accounts;
 }
 
 std::string UserAccountsDelegateChromeOS::GetAccountDisplayName(
     const std::string& account_id) {
   const user_manager::User* user =
       ProfileHelper::Get()->GetUserByProfile(user_profile_);
-  if (gaia::AreEmailsSame(user->email(), account_id) &&
+  if (gaia::AreEmailsSame(user->GetUserID().GetUserEmail(), account_id) &&
       !user->display_email().empty())
     return user->display_email();
   return account_id;
 }
 
 void UserAccountsDelegateChromeOS::DeleteAccount(
     const std::string& account_id) {
   MutableProfileOAuth2TokenService* oauth2_token_service =
       ProfileOAuth2TokenServiceFactory::GetPlatformSpecificForProfile(
           user_profile_);
   oauth2_token_service->RevokeCredentials(account_id);
 }
 
 void UserAccountsDelegateChromeOS::LaunchAddAccountDialog() {
   ui::InlineLoginDialog::Show(user_profile_);
 }
 
 void UserAccountsDelegateChromeOS::OnRefreshTokenAvailable(
     const std::string& account_id) {
   NotifyAccountListChanged();
 }
 
 void UserAccountsDelegateChromeOS::OnRefreshTokenRevoked(
     const std::string& account_id) {
   NotifyAccountListChanged();
 }
 
 }  // namespace chromeos