Workaround for Chrome not specifying which request is main_frame under some circumstances

webrequest.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 38 matching lines @@
 });
 
 var frames = {};
 
 function onBeforeRequest(details)
 {
   if (details.tabId == -1)
     return {};
 
   var type = details.type;
-  
-  // Workaround: Under some circumstances Chrome 29+ gives top frame the
-  // type "object" instead of "main_frame". We work around that by assuming
-  // that the first request belongs to the top frame.
-  if (!(details.tabId in frames))
+
+  // Assume that the first request belongs to the top frame. Chrome may give the
+  // top frame the type "object" instead of "main_frame".
+  // https://code.google.com/p/chromium/issues/detail?id=281711
+  if (details.frameId == 0 && !(details.tabId in frames) && type == "object")

[Wladimir Palant, 2013/08/30 12:16:25]

Please ensure details.tabId >= 0, tabId -1 means a request that isn't associated
with any tab (e.g. extension).

     type = "main_frame";

[Wladimir Palant, 2013/08/29 05:57:40]

There are two assumption here which both seem to be wrong:

1) This issue will always manifest itself as an unknown tab ID. I doubt that
this is the case - if the user navigates to that YouTube URL in an existing tab
then the tab will be known.

2) A request initiated from an unknown tab is always this issue. However, we
will only get the top request if it comes from HTTP or HTTPS. A local file
making requests to remote resources will show up as an unknown tab. Also, some
requests (like requests made by extensions) aren't associated with tabs - tabId
will be -1 then.

-  
+
   if (type == "main_frame" || type == "sub_frame")
     recordFrame(details.tabId, details.frameId, details.parentFrameId, details.url);
 
   if (type == "main_frame")
     return {};
 
   // Type names match Mozilla's with main_frame and sub_frame being the only exceptions.
   if (type == "sub_frame")
     type = "SUBDOCUMENT";
   else
@@ skipping 121 matching lines @@
     parent = frameData.parent;
     parentData = getFrameData(tabId, parent);
 
     var frameUrl = frameData.url;
     var parentUrl = (parentData ? parentData.url : frameUrl);
     if ("keyException" in frameData || isWhitelisted(frameUrl, parentUrl, type))
       return true;
   }
   return false;
 }