Update a bug number referenced by some TODOs, to point at the new bug for tra...

net/base/host_resolver_impl.cc

Index: net/base/host_resolver_impl.cc
===================================================================
--- net/base/host_resolver_impl.cc	(revision 22339)
+++ net/base/host_resolver_impl.cc	(working copy)
@@ -369,9 +369,9 @@
 // cancelled requests from Job::requests_.
 void HostResolverImpl::CancelRequest(RequestHandle req_handle) {
   if (shutdown_) {
-    // TODO(eroman): temp hack for: http://crbug.com/16972.
-    // Because we destroy outstanding requests during Shutdown() as part of
-    // hack http://crbug.com/15513, |req_handle| is already cancelled.
+    // TODO(eroman): temp hack for: http://crbug.com/18373
+    // Because we destroy outstanding requests during Shutdown(),
+    // |req_handle| is already cancelled.
     LOG(ERROR) << "Called HostResolverImpl::CancelRequest() after Shutdown().";
     StackTrace().PrintBacktrace();
     return;