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

chrome/browser/chromeos/preferences.cc

 // 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.
 
 #include "chrome/browser/chromeos/preferences.h"
 
 #include <vector>
 
 #include "ash/autoclick/autoclick_controller.h"
 #include "ash/shell.h"
@@ skipping 373 matching lines @@
 }
 
 void Preferences::OnPreferenceChanged(const std::string& pref_name) {
   ApplyPreferences(REASON_PREF_CHANGED, pref_name);
 }
 
 void Preferences::ApplyPreferences(ApplyReason reason,
                                    const std::string& pref_name) {
   DCHECK(reason != REASON_PREF_CHANGED || !pref_name.empty());
   const bool user_is_owner =
-      user_manager::UserManager::Get()->GetOwnerEmail() == user_->email();
+      user_manager::UserManager::Get()->GetOwnerID() == user_->GetUserID();
   const bool user_is_active = user_->is_active();
 
   system::TouchpadSettings touchpad_settings;
   system::MouseSettings mouse_settings;
 
   if (user_is_primary_ && (reason == REASON_INITIALIZATION ||
                            pref_name == prefs::kPerformanceTracingEnabled)) {
     const bool enabled = performance_tracing_enabled_.GetValue();
     if (enabled)
       tracing_manager_ = TracingManager::Create();
@@ skipping 279 matching lines @@
   touch_hud_projection_enabled_.SetValue(enabled);
 }
 
 void Preferences::ActiveUserChanged(const user_manager::User* active_user) {
   if (active_user != user_)
     return;
   ApplyPreferences(REASON_ACTIVE_USER_CHANGED, "");
 }
 
 }  // namespace chromeos