How to map response to request when using "http-on-modify-request" and "http-on-examine-response"?

How to map incoming responses to the outgoing requests when using HTTP observers: https://dev开发者_开发技巧eloper.mozilla.org/en/Setting_HTTP_request_headers#Observers ?

Compare nsIHttpChannel objects, like HttpFox does:

getPendingRequestForRequestEvent: function(request) {
   // check for matching request
   for (var i = 0; i < this.Requests.length; i++) {
      if (request.HttpChannel === this.Requests[i].HttpChannel) {
         return i;
      }
   }

   // no match found
   return -1;
},