Fixed crash in the proxy. Reference has been passed between threads,

chrome/service/cloud_print/cloud_print_proxy.cc

Index: chrome/service/cloud_print/cloud_print_proxy.cc
===================================================================
--- chrome/service/cloud_print/cloud_print_proxy.cc	(revision 108685)
+++ chrome/service/cloud_print/cloud_print_proxy.cc	(working copy)
@@ -188,15 +188,6 @@
     service_prefs_->GetString(prefs::kCloudPrintProxyId, &info->proxy_id);
 }
 
-// Notification methods from the backend. Called on UI thread.
-void CloudPrintProxy::OnPrinterListAvailable(
-    const printing::PrinterList& printer_list) {
-  DCHECK(CalledOnValidThread());
-  // We could potentially show UI here allowing the user to select which
-  // printers to register. For now, we just register all.
-  backend_->RegisterPrinters(printer_list);
-}
-
 void CloudPrintProxy::OnAuthenticated(
     const std::string& robot_oauth_refresh_token,
     const std::string& robot_email,