Fix a long standing leak on cancellation of renderer-initiated URLRequests.

content/child/resource_dispatcher.cc

Index: content/child/resource_dispatcher.cc
===================================================================
--- content/child/resource_dispatcher.cc	(revision 240334)
+++ content/child/resource_dispatcher.cc	(working copy)
@@ -585,11 +585,8 @@
     return;
   }
 
-  SiteIsolationPolicy::OnRequestComplete(request_id);
-  PendingRequestInfo& request_info = it->second;
-  ReleaseResourcesInMessageQueue(&request_info.deferred_message_queue);
-  pending_requests_.erase(it);
-
+  // |request_id| will be removed from |pending_requests_| when
+  // OnRequestComplete returns with ERR_ABORTED.
   message_sender()->Send(new ResourceHostMsg_CancelRequest(request_id));
 }