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

webrequest.js

Index: webrequest.js
===================================================================
--- a/webrequest.js
+++ b/webrequest.js
@@ -56,6 +56,13 @@
     return {};
 
   var type = details.type;
+
+  // 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";
+
   if (type == "main_frame" || type == "sub_frame")
     recordFrame(details.tabId, details.frameId, details.parentFrameId, details.url);