Issue 154 - Added UI for devtools panel on Chrome

ext/background.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 66 matching lines @@
   global.ext.PageMap = PageMap;
 
   global.ext.showOptions = function(callback)
   {
     if (top.location.href.indexOf("options.html") == -1)
       window.open("options.html", "_blank");
 
     if (callback)
       callback();
   };
+
+  global.ext.devtools = {
+    onCreated: {
+      addListener: function(listener)
+      {
+        window.addEventListener("message", function(event)
+        {
+          if (event.data.type == "devtools")
+            listener(new ext.Page(event.source));
+        });
+      }
+    }
+  };
 })(this);