Added backwards compatibility for Chrome's old messaging API

chrome/background.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2013 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 176 matching lines @@
     },
     _prepareExtraArguments: function(urls)
     {
       return [urls ? {urls: urls} : {}, ["blocking"]];
     }
   };
 
 
   /* Tabs */
 
+  var sendMessage = chrome.tabs.sendMessage || chrome.tabs.sendRequest;
+
   var PageAction = function(tabId)
   {
     this._tabId = tabId;
   };
   PageAction.prototype = {
     setIcon: function(path)
     {
       chrome.pageAction.setIcon({tabId: this._tabId, path: path});
     },
     setTitle: function(title)
@@ skipping 26 matching lines @@
     close: function()
     {
       chrome.tabs.remove(this._id);
     },
     activate: function()
     {
       chrome.tabs.update(this._id, {selected: true});
     },
     sendMessage: function(message, responseCallback)
     {
-      chrome.tabs.sendMessage(this._id, message, responseCallback);
+      sendMessage(this._id, message, responseCallback);
     }
   };
 
   TabMap = function()
   {
     this._map = {};
     this.delete = this.delete.bind(this);
   };
   TabMap.prototype = {
     get: function(tab)
@@ skipping 88 matching lines @@
     onCompleted: new CompletedTabEventTarget(),
     onActivated: new ActivatedTabEventTarget(),
     onRemoved: new RemovedTabEventTarget()
   };
 
   ext.webRequest = {
     onBeforeRequest: new BeforeRequestEventTarget(),
     handlerBehaviorChanged: chrome.webRequest.handlerBehaviorChanged
   };
 })();