chromium/chrome/test/data/chromedriver/shared_worker.html

<!DOCTYPE html>
<html>
  <body>
    <script>
       // Create a dummy shared worker. The SharedWorker constructor is bound by
       // the same origin policy, so we can't just load about:blank or a data:
       // URL and call ExecuteScript to create one - this needs to be in a page
       // that is served from the test web server.
       var worker = new SharedWorker('#');
    </script>
  </body>
</html>