Issue 3251 - Simplify messaging from child scripts to parent

lib/elemHide.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 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 62 matching lines @@
    * Inidicates whether the element hiding stylesheet is currently applied.
    * @type Boolean
    */
   applied: false,
 
   /**
    * Called on module startup.
    */
   init: function()
   {
-    let messageManager = Cc["@mozilla.org/parentprocessmessagemanager;1"]
-                           .getService(Ci.nsIMessageListenerManager);
-    let hitHandler = (message => {
-      let result = ElemHide.shouldHide(message.data);
-      let target = message.target.QueryInterface(Ci.nsIMessageSender);
-      target.sendAsyncMessage(message.data.responseMessage, result);
+    Utils.addChildMessageListener("AdblockPlus:ElemHideHit", (data) => {
+      return ElemHide.shouldHide(data);
     });
-    messageManager.addMessageListener("AdblockPlus:ElemHideHit", hitHandler);
-    onShutdown.add(() => messageManager.removeMessageListener("AdblockPlus:ElemHideHit", hitHandler));
 
     Prefs.addListener(function(name)
     {
       if (name == "enabled")
         ElemHide.apply();
     });
     onShutdown.add(() => ElemHide.unapply());
 
     let styleFile = IO.resolveFilePath(Prefs.data_directory);
     styleFile.append("elemhide.css");
@@ skipping 312 matching lines @@
       let filter = filterByKey[key];
       if (specificOnly && (!filter.domains || filter.domains[""]))
         continue;
 
       if (filter.isActiveOnDomain(domain) && !this.getException(filter, domain))
         result.push(filter.selector);
     }
     return result;
   }
 };