Use method that checks for autoupdate.

chrome/browser/chromeos/login/screen_locker.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/login/screen_locker.h"
 
 #include <string>
 #include <vector>
 
 #include "ash/ash_switches.h"
 #include "ash/desktop_background/desktop_background_controller.h"
 #include "ash/shell.h"
 #include "ash/wm/session_state_controller.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "base/timer.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/chromeos/login/authenticator.h"
 #include "chrome/browser/chromeos/login/login_performer.h"
 #include "chrome/browser/chromeos/login/login_utils.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
 #include "chrome/browser/chromeos/login/webui_screen_locker.h"
+#include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/signin/signin_manager.h"
 #include "chrome/browser/signin/signin_manager_factory.h"
 #include "chrome/browser/sync/profile_sync_service.h"
 #include "chrome/browser/sync/profile_sync_service_factory.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_window.h"
@@ skipping 240 matching lines @@
 }
 
 void ScreenLocker::ClearErrors() {
   delegate_->ClearErrors();
 }
 
 void ScreenLocker::EnableInput() {
   delegate_->SetInputEnabled(true);
 }
 
 void ScreenLocker::Signout() {

[Nikita (slow), 2013/04/08 17:05:53]

It seem that there're autotests that employ this functionality.

I've executed cros_* trybots to check it.

   delegate_->ClearErrors();
   content::RecordAction(UserMetricsAction("ScreenLocker_Signout"));
-  DBusThreadManager::Get()->GetSessionManagerClient()->StopSession();
+  // We expect that this call will not wait for any user input.
+  // If it changes at some point, we will need to force exit.
+  chrome::AttemptUserExit();
 
   // Don't hide yet the locker because the chrome screen may become visible
   // briefly.
 }
 
 void ScreenLocker::ShowErrorMessage(int error_msg_id,
                                     HelpAppLauncher::HelpTopic help_topic_id,
                                     bool sign_out_only) {
   delegate_->SetInputEnabled(!sign_out_only);
   delegate_->ShowErrorMessage(error_msg_id, help_topic_id);
@@ skipping 124 matching lines @@
       content::Details<bool>(&state));
   VLOG(1) << "Calling session manager's HandleLockScreenShown D-Bus method";
   DBusThreadManager::Get()->GetSessionManagerClient()->NotifyLockScreenShown();
 }
 
 content::WebUI* ScreenLocker::GetAssociatedWebUI() {
   return delegate_->GetAssociatedWebUI();
 }
 
 }  // namespace chromeos