The Tor Browser / file revision

 this.EXPORTED_SYMBOLS = ['checkFromJSM'];

 this.checkFromJSM = function checkFromJSM(ok, is, finish) {

   let worker = new ChromeWorker("jsm_url_worker.js");

   worker.onmessage = function(event) {

    if (event.data.type == 'finish') {

      finish();

     } else if (event.data.type == 'status') {

       ok(event.data.status, event.data.msg);

     }

   }

   var self = this;

   worker.onerror = function(event) {

     is(event.target, worker);

     ok(false, "Worker had an error: " + event.data);

     self.worker.terminate();

     finish();

   };

   worker.postMessage(0);

 }