Display error message when user try to open a locked supervised user profile when force-sign-in is …

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

Index: chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
diff --git a/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc b/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
index 22351cfc465d5502a82e3a371a188675607530af..fd08dced607052a9dfba1ade7e70f2bc055e73c5 100644
--- a/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
+++ b/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
@@ -43,6 +43,8 @@
 #include "chrome/browser/ui/singleton_tabs.h"
 #include "chrome/browser/ui/user_manager.h"
 #include "chrome/browser/ui/webui/profile_helper.h"
+#include "chrome/browser/ui/webui/signin/login_ui_service.h"
+#include "chrome/browser/ui/webui/signin/login_ui_service_factory.h"
 #include "chrome/common/chrome_features.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
@@ -464,6 +466,17 @@ void UserManagerScreenHandler::HandleAuthenticatedLaunchUser(
     // password token, the user must perform a full online reauth.
     UserManager::ShowReauthDialog(browser_context, email_address_,
                                   signin_metrics::Reason::REASON_UNLOCK);
+  } else if (entry->IsSigninRequired() && entry->IsSupervised()) {
+    // Supervised profile will only be locked when force-sign-in is enabled
+    // and it shouldn't be unlocked. Display the error message directly via
+    // the system profile to avoid profile creation.
+    LoginUIServiceFactory::GetForProfile(
+        Profile::FromWebUI(web_ui())->GetOriginalProfile())
+        ->DisplayLoginResult(nullptr,
+                             l10n_util::GetStringUTF16(
+                                 IDS_SUPERVISED_USER_NOT_ALLOWED_BY_POLICY),
+                             base::string16());
+    UserManager::ShowDialogAndDisplayErrorMessage(browser_context);
   } else {
     // Fresh sign in via user manager without existing email address.
     UserManager::ShowSigninDialog(browser_context, profile_path);