Lock profile before sign in when force sign in is enabled.

chrome/browser/ui/webui/signin/login_ui_service.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/ui/webui/signin/login_ui_service.h"
 
 #include "build/build_config.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/signin_promo.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/chrome_pages.h"
 #include "chrome/browser/ui/profile_chooser_constants.h"
 #include "chrome/browser/ui/scoped_tabbed_browser_displayer.h"
+#include "chrome/browser/ui/user_manager.h"
 #include "chrome/browser/ui/webui/signin/login_ui_service_factory.h"
 #include "chrome/common/url_constants.h"
 #include "components/signin/core/browser/signin_header_helper.h"
 #include "components/signin/core/common/profile_management_switches.h"
 
 LoginUIService::LoginUIService(Profile* profile)
 #if !defined(OS_CHROMEOS)
     : profile_(profile)
 #endif
 {
@@ skipping 48 matching lines @@
 void LoginUIService::DisplayLoginResult(Browser* browser,
                                         const base::string16& error_message,
                                         const base::string16& email) {
 #if defined(OS_CHROMEOS)
   // ChromeOS doesn't have the avatar bubble so it never calls this function.
   NOTREACHED();
 #endif
   last_login_result_ = error_message;
   last_login_error_email_ = email;
   if (switches::IsMaterialDesignUserMenu() && !error_message.empty()) {
-    browser->ShowModalSigninErrorWindow();
-  } else {
+    if (browser)
+      browser->ShowModalSigninErrorWindow();
+    else
+      UserManager::DisplayErrorMessage();
+  } else if (browser) {
     browser->window()->ShowAvatarBubbleFromAvatarButton(
         error_message.empty() ? BrowserWindow::AVATAR_BUBBLE_MODE_CONFIRM_SIGNIN
                               : BrowserWindow::AVATAR_BUBBLE_MODE_SHOW_ERROR,
         signin::ManageAccountsParams(),
         signin_metrics::AccessPoint::ACCESS_POINT_EXTENSIONS);
   }

[Roger Tawa OOO till Jul 10th, 2016/11/08 15:16:11]

Shouldn't there be an else block here for when browser is null?

[zmin, 2016/11/08 18:39:07]

Without force-sign-in,  the DisplayLoginResult will be called only if browser is
not null.

With force-sign-in, the error message will be displayed in UserManager without
browser(so browser could be null). However, UserManager error message only
supports the new MaterialDesign. The old UI simply ignores the error message if
there is no browser.

 }
 
 const base::string16& LoginUIService::GetLastLoginResult() const {
   return last_login_result_;
 }
 
 const base::string16& LoginUIService::GetLastLoginErrorEmail() const {
   return last_login_error_email_;
 }