Issue 1663 - Emulate background page and implement proper message responder

ext/common.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2014 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 (function(global)
 {
   if (!global.ext)
     global.ext = {};
 
+  function Page(source)
+  {
+    this._source = source;
+  }
+  Page.prototype =
+  {
+    sendMessage: function(message)
+    {
+      this._source.postMessage({
+        type: "message",
+        messageId: -1,
+        payload: message
+      }, "*");
+    }
+  };
+
+  global.ext.Page = Page;
+
   /* Message passing */
 
   global.ext.onMessage =
   {
     addListener: function(listener)
     {
-      listener.__wrapper = function(event)
+      listener._extWrapper = function(event)
       {
         if (event.data.type != "message")
           return;
 
         var message = event.data.payload;
         var messageId = event.data.messageId;
         var sender = {
-          sendMessage: function(message)
-          {
-            event.source.postMessage({
-              type: "message",
-              messageId: -1,
-              payload: message
-            }, "*");
-          }
+          page: new Page(event.source)
         };
         var callback = function(message)
         {
           event.source.postMessage({
             type: "response",
             messageId: messageId,
             payload: message
           }, "*");
         };
         listener(message, sender, callback);
       };
-      window.addEventListener("message", listener.__wrapper, false);
+      window.addEventListener("message", listener._extWrapper, false);
     },
 
     removeListener: function(listener)
     {
-      if ("__wrapper" in listener)
-        window.removeEventListener("message", listener.__wrapper, false);
+      if ("_extWrapper" in listener)
+        window.removeEventListener("message", listener._extWrapper, false);
     }
   };
 
   /* I18n */
 
   var getLocaleCandidates = function(selectedLocale)
   {
     var candidates = [];
     var defaultLocale = "en-US";
 
@@ skipping 104 matching lines @@
         }
 
         if (locales.length == 0)
           return "";
 
         readCatalog(locales.shift());
       }
     }
   };
 })(this);