Issue 3868 - Use the new FilterNotifier API

lib/stats.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 17 matching lines @@
  * Gets the number of requests blocked on the given page.
  *
  * @param  {Page} page
  * @return {Number}
  */
 exports.getBlockedPerPage = function(page)
 {
   return blockedPerPage.get(page) || 0;
 };
 
-FilterNotifier.addListener(function(action, item, newValue, oldValue, page)
+FilterNotifier.on("filter.hitCount", (filter, newValue, oldValue, page) =>
 {
-  if (action != "filter.hitCount" || !page)
-    return;
-
-  if (!(item instanceof BlockingFilter))
+  if (!(filter instanceof BlockingFilter) || !page)
     return;
 
   Prefs.blocked_total++;
 
   let blocked = blockedPerPage.get(page) || 0;
   blockedPerPage.set(page, ++blocked);
 
   // Update number in icon
   if (Prefs.show_statsinicon)
   {
     page.browserAction.setBadge({
       color: badgeColor,
       number: blocked
     });
   }
 });
 
-Prefs.on("show_statsinicon", function()
+Prefs.on("show_statsinicon", () =>
 {
   ext.pages.query({}, function(pages)
   {
     for (var i = 0; i < pages.length; i++)
     {
       let page = pages[i];
       let badge = null;
 
       if (Prefs.show_statsinicon)
       {
         let blocked = blockedPerPage.get(page);
         if (blocked)
         {
           badge = {
             color: badgeColor,
             number: blocked
           };
         }
       }
 
       page.browserAction.setBadge(badge);
     }
   });
 });