Apply content-security-policy to the HTML options page. This is a

chrome/browser/resources/shared/js/chromeos/accounts_user_name_edit.js

 // Copyright (c) 2011 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.accounts', function() {
   const Event = cr.Event;
 
   // Email alias only, assuming it's a gmail address.
   //   e.g. 'john'
   //        {name: 'john', email: 'john@gmail.com'}
@@ skipping 104 matching lines @@
         this.select();
       }
     }
   };
 
   return {
     UserNameEdit: UserNameEdit
   };
 });