const { classes: Cc, interfaces: Ci, utils: Cu } = Components;
try 
{
  Cu.import("resource://gre/modules/Services.jsm");
  var srcURL="http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-mozilla-aurora-l10n/firefox-6.0a2.ru.win32.zip";
  var file=Services.dirsvc.get("Desk", Ci.nsILocalFile);
  file.append(srcURL.replace(/^.*\//,""));
  if (!file.exists()) file.create(0x00,0644);
  var fURI=Services.io.newURI(srcURL,null,null);
  const nsIWBP=Ci.nsIWebBrowserPersist;
  var oPersist=Cc["@mozilla.org/embedding/browser/nsWebBrowserPersist;1"].createInstance(nsIWBP);
  with(nsIWBP) oPersist.persistFlags=PERSIST_FLAGS_REPLACE_EXISTING_FILES | PERSIST_FLAGS_FROM_CACHE;
  oPersist.progressListener=
  {
    onProgressChange: function(aWebProgress,aRequest,aCurSelfProgress,
                  aMaxSelfProgress,aCurTotalProgress,aMaxTotalProgress) {},
    onStateChange: function(aWebProgress, aRequest, aStateFlags, aStatus)
    {
      with(Ci.nsIWebProgressListener)
        if ((aStateFlags & STATE_STOP)==STATE_STOP)
          Services.console.logStringMessage("dowloading completed");
    }
  }
  oPersist.saveURI(fURI,null,null,null,null,file);
  Services.console.logStringMessage("downloading started.");
} catch(err){Services.console.logStringMessage(err+"\n"+err.stack);}

var downloadCompleted = false;

  // download the file first
  var persist = Components.classes["@mozilla.org/embedding/browser/nsWebBrowserPersist;1"]
                  .createInstance(Components.interfaces.nsIWebBrowserPersist);
  // get OS temp folder
  var file = Components.classes["@mozilla.org/file/directory_service;1"]
                .getService(Components.interfaces.nsIProperties)
                .get("TmpD", Components.interfaces.nsIFile);
  file.createUnique(Components.interfaces.nsIFile.NORMAL_FILE_TYPE, 0666);

  var fURI = Services.io.newURI(url,null,null);
    const nsIWBP = Components.interfaces.nsIWebBrowserPersist;
    const flags = nsIWBP.PERSIST_FLAGS_REPLACE_EXISTING_FILES;
    persist.persistFlags = flags | nsIWBP.PERSIST_FLAGS_FROM_CACHE;

  persist.progressListener = {
    onProgressChange: function(aWebProgress, aRequest, aCurSelfProgress, aMaxSelfProgress, aCurTotalProgress, aMaxTotalProgress) {
      },
    onStateChange: function(aWebProgress, aRequest, aStateFlags, aStatus) {
      if (aStateFlags & Components.interfaces.nsIWebProgressListener.STATE_STOP) {
         downloadCompleted = true; // file has been downloaded        
      }
    }
  }
  persist.saveURI(fURI, null, null, null, "", file);  

  var thread = Components.classes["@mozilla.org/thread-manager;1"]
                        .getService(Components.interfaces.nsIThreadManager)
                        .currentThread;
  while (!downloadCompleted) // emulate synchronous request
    thread.processNextEvent(true);

var aReferrer = Services.io.newURI(url,null,null);
  persist.saveURI(fURI, null, aReferrer, null, "", file);