MD User Manager: Error message if pref doesn't allow creating supervised user.

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

 // Copyright 2016 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/signin_create_profile_handler.h"
 
 #include <stddef.h>
 #include <string>
 #include <vector>
 
@@ skipping 555 matching lines @@
       // We are only interested in Profile::CREATE_STATUS_INITIALIZED when
       // everything is ready.
       if (!IsAccountConnected(custodian_profile) ||
           HasAuthError(custodian_profile)) {
         ShowProfileCreationError(nullptr, l10n_util::GetStringFUTF16(
           IDS_PROFILES_CREATE_CUSTODIAN_ACCOUNT_DETAILS_OUT_OF_DATE_ERROR,
           base::ASCIIToUTF16(custodian_profile->GetProfileUserName())));
         return;
       }
 
-      // TODO(mahmadi): return proper error message if policy-controlled prefs
-      // prohibit adding supervised users (also disable the controls in the UI).
       PrefService* prefs = custodian_profile->GetPrefs();
-      if (!prefs->GetBoolean(prefs::kSupervisedUserCreationAllowed))
+      if (!prefs->GetBoolean(prefs::kSupervisedUserCreationAllowed)) {
+        ShowProfileCreationError(
+            nullptr,
+            l10n_util::GetStringUTF16(
+                IDS_PROFILES_CREATE_SUPERVISED_NOT_ALLOWED_BY_POLICY));
         return;
+      }
 
       if (!supervised_user_id.empty()) {
         profile_creation_type_ = SUPERVISED_PROFILE_IMPORT;
 
         // Load all supervised users managed by this user in order to
         // check if this supervised user already exists on this device.
         SupervisedUserSyncService* supervised_user_sync_service =
             SupervisedUserSyncServiceFactory::GetForProfile(custodian_profile);
         if (supervised_user_sync_service) {
           supervised_user_sync_service->GetSupervisedUsersAsync(base::Bind(
@@ skipping 211 matching lines @@
   profiles::OpenBrowserWindowForProfile(
       base::Bind(&SigninCreateProfileHandler::OnBrowserReadyCallback,
                  weak_ptr_factory_.GetWeakPtr()),
       false,  // Don't create a window if one already exists.
       true,  // Create a first run window.
       profile,
       Profile::CREATE_STATUS_INITIALIZED);
 }
 
 #endif