Issue 5835 - Add some notification related message handlers

background.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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 122 matching lines @@
         let index = categories.indexOf(category);
         if (index == -1)
           categories.push(category);
         else
           categories.splice(index, 1);
         modules.prefs.Prefs.notifications_ignoredcategories = categories;
       }
     }
   };
 
+  modules.notificationHelper = {
+    getActiveNotification()
+    {
+    },
+    shouldDisplay()
+    {
+      return true;
+    }
+  };
+
   let subscriptionServer = "https://easylist-downloads.adblockplus.org";
   let subscriptionDetails = {
     [`${subscriptionServer}/easylistgermany+easylist.txt`]: {
       title: "EasyList Germany+EasyList",
       installed: true
     },
     [`${subscriptionServer}/exceptionrules.txt`]: {
       title: "Allow non-intrusive advertising",
       installed: true
     },
@@ skipping 437 matching lines @@
       },
       filter: {
         text: "||example.com/some-annoying-popup$popup",
         whitelisted: false,
         userDefined: true,
         subscription: null
       }
     });
   });
 }());