The WebURLResponse will be null if the network request fails. So, a null che...

webkit/glue/alt_error_page_resource_fetcher.cc

Index: webkit/glue/alt_error_page_resource_fetcher.cc
===================================================================
--- webkit/glue/alt_error_page_resource_fetcher.cc	(revision 20031)
+++ webkit/glue/alt_error_page_resource_fetcher.cc	(working copy)
@@ -53,7 +53,7 @@
   if (!delegate)
     return;
 
-  if (response.httpStatusCode() == 200) {
+  if (!response.isNull() && response.httpStatusCode() == 200) {
     // We successfully got a response from the alternate error page server, so
     // load it.
     delegate->LoadNavigationErrorPage(web_frame_, failed_request_,
@@ -64,4 +64,4 @@
   }
 }
 
-}  // namespace webkit_glue
+}  // namespace webkit_glue