Issue 3208 - Send Private Browsing flag separately from the frame structure

lib/child/utils.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 21 matching lines @@
   {
     let frame = {
       location: window.location.href,
       sitekey: null
     };
 
     let documentElement = window.document && window.document.documentElement;
     if (documentElement)
       frame.sitekey = documentElement.getAttribute("data-adblockkey")
 
-    if (window == window.parent)
-      frame.privateBrowsing = PrivateBrowsingUtils.isWindowPrivate(window);
-
     frames.push(frame);
     window = (window != window.parent ? window.parent : null);
   }
   return frames;
-}
+};
+
+/**
+ * Checks whether Private Browsing mode is enabled for a content window.
+ * @return {Boolean}
+ */
+let isPrivate = exports.isPrivate = function(/**Window*/ window)
+{
+  return PrivateBrowsingUtils.isWindowPrivate(window);
+};