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

chrome/browser/chromeos/chrome_browser_main_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/chromeos/chrome_browser_main_chromeos.h"
 
 #include <string>
 #include <vector>
 
 #include "ash/ash_switches.h"
@@ skipping 263 matching lines @@
   }
 
   // If we're not running on real Chrome OS hardware (or under VM), and are not
   // showing the login manager or attempting a command line login, login with a
   // stub user.
   if (!base::SysInfo::IsRunningOnChromeOS() &&
       !parsed_command_line().HasSwitch(switches::kLoginManager) &&
       !parsed_command_line().HasSwitch(switches::kLoginUser) &&
       !parsed_command_line().HasSwitch(switches::kGuestSession)) {
     singleton_command_line->AppendSwitchASCII(switches::kLoginUser,
-                                              chromeos::login::kStubUser);
+                                              chromeos::login::GetStubUserID().GetUserEmail());
     if (!parsed_command_line().HasSwitch(switches::kLoginProfile)) {
       singleton_command_line->AppendSwitchASCII(switches::kLoginProfile,
                                                 chrome::kTestUserProfileDir);
     }
     LOG(WARNING) << "Running as stub user with profile dir: "
                  << singleton_command_line->GetSwitchValuePath(
                      switches::kLoginProfile).value();
   }
 
 #if defined(GOOGLE_CHROME_BUILD)
@@ skipping 148 matching lines @@
       ShouldAutoLaunchKioskApp(parsed_command_line())) {
     WizardController::SetZeroDelays();
   }
 
   power_prefs_.reset(new PowerPrefs(PowerPolicyController::Get()));
 
   // In Aura builds this will initialize ash::Shell.
   ChromeBrowserMainPartsLinux::PreProfileInit();
 
   if (immediate_login) {
-    const std::string user_id = login::CanonicalizeUserID(
-        parsed_command_line().GetSwitchValueASCII(switches::kLoginUser));
+    const user_manager::UserID user_id(std::string() /* gaia_id */, login::CanonicalizeUserID(

[Denis Kuznetsov (DE-MUC), 2015/06/10 16:50:45]

FromUserEmail()

+        parsed_command_line().GetSwitchValueASCII(switches::kLoginUser)));
     user_manager::UserManager* user_manager = user_manager::UserManager::Get();
 
     if (policy::IsDeviceLocalAccountUser(user_id, NULL) &&
         !user_manager->IsKnownUser(user_id)) {
       // When a device-local account is removed, its policy is deleted from disk
       // immediately. If a session using this account happens to be in progress,
       // the session is allowed to continue with policy served from an in-memory
       // cache. If Chrome crashes later in the session, the policy becomes
       // completely unavailable. Exit the session in that case, rather than
       // allowing it to continue without policy.
       chrome::AttemptUserExit();
       return;
     }
 
     // In case of multi-profiles --login-profile will contain user_id_hash.
     std::string user_id_hash =
         parsed_command_line().GetSwitchValueASCII(switches::kLoginProfile);
     user_manager->UserLoggedIn(user_id, user_id_hash, true);
-    VLOG(1) << "Relaunching browser for user: " << user_id
+    VLOG(1) << "Relaunching browser for user: " << user_id.Serialize()

[Denis Kuznetsov (DE-MUC), 2015/06/10 16:50:45]

Not sure that Serialize() method is suitable for logging.
Add some ToString() / value() method.

             << " with hash: " << user_id_hash;
   }
 }
 
 class GuestLanguageSetCallbackData {
  public:
   explicit GuestLanguageSetCallbackData(Profile* profile) : profile(profile) {
   }
 
   // Must match SwitchLanguageCallback type.
@@ skipping 293 matching lines @@
   // Destroy DBus services immediately after threads are stopped.
   dbus_services_.reset();
 
   ChromeBrowserMainPartsLinux::PostDestroyThreads();
 
   // Destroy DeviceSettingsService after g_browser_process.
   DeviceSettingsService::Shutdown();
 }
 
 }  //  namespace chromeos