The Tor Browser / file revision

 var prefetch = Cc["@mozilla.org/prefetch-service;1"].

                getService(Ci.nsIPrefetchService);

 var ios = Cc["@mozilla.org/network/io-service;1"].

           getService(Ci.nsIIOService);

 var prefs = Cc["@mozilla.org/preferences-service;1"].

             getService(Ci.nsIPrefBranch);

 function run_test() {

   // Fill up the queue

   prefs.setBoolPref("network.prefetch-next", true);

   for (var i = 0; i < 5; i++) {

     var uri = ios.newURI("http://localhost/" + i, null, null);

     prefetch.prefetchURI(uri, uri, null, true);

   }

   // Make sure the queue has items in it...

   var queue = prefetch.enumerateQueue();

   do_check_true(queue.hasMoreElements());

   // Now disable the pref to force the queue to empty...

   prefs.setBoolPref("network.prefetch-next", false);

   queue = prefetch.enumerateQueue();

   do_check_false(queue.hasMoreElements());

   // Now reenable the pref, and add more items to the queue.

   prefs.setBoolPref("network.prefetch-next", true);

   for (var i = 0; i < 5; i++) {

     var uri = ios.newURI("http://localhost/" + i, null, null);

     prefetch.prefetchURI(uri, uri, null, true);

   }

   queue = prefetch.enumerateQueue();

   do_check_true(queue.hasMoreElements());

 }