Fix issues with supervised user recreation

chrome/browser/resources/options/managed_user_import.js

 // Copyright 2013 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.
 
 cr.define('options', function() {
   var OptionsPage = options.OptionsPage;
   var ArrayDataModel = cr.ui.ArrayDataModel;
 
   /**
    * ManagedUserImportOverlay class.
@@ skipping 163 matching lines @@
       if (!managedUsers) {
         $('managed-user-list').dataModel = null;
         return;
       }
 
       managedUsers.sort(function(a, b) {
         return a.name.localeCompare(b.name);
       });
 
       $('managed-user-list').dataModel = new ArrayDataModel(managedUsers);
-      if (managedUsers.length == 0)
+      if (managedUsers.length == 0) {
         this.onError_(loadTimeData.getString('noExistingManagedUsers'));
+        $('managed-user-import-ok').disabled = true;
+      }
     },
 
     /**
      * @private
      */
     hideErrorBubble_: function() {
       $('managed-user-import-error-bubble').hidden = true;
     },
 
     /**
@@ skipping 31 matching lines @@
       var instance = ManagedUserImportOverlay.getInstance();
       return instance[name + '_'].apply(instance, arguments);
     };
   });
 
   // Export
   return {
     ManagedUserImportOverlay: ManagedUserImportOverlay,
   };
 });