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

chrome/browser/ui/webui/signin/login_ui_service.cc

Index: chrome/browser/ui/webui/signin/login_ui_service.cc
diff --git a/chrome/browser/ui/webui/signin/login_ui_service.cc b/chrome/browser/ui/webui/signin/login_ui_service.cc
index 9250df6b405dab3bd918e3d1a5251356c508aea7..11c4093305b68dcdd15f0d171910a2ef2309ab15 100644
--- a/chrome/browser/ui/webui/signin/login_ui_service.cc
+++ b/chrome/browser/ui/webui/signin/login_ui_service.cc
@@ -12,6 +12,7 @@
 #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"
@@ -80,8 +81,11 @@ void LoginUIService::DisplayLoginResult(Browser* browser,
   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,