ClientCertStoreChromeOS: support additional non-platform certs.

net/ssl/client_cert_store_nss.cc

Index: net/ssl/client_cert_store_nss.cc
diff --git a/net/ssl/client_cert_store_nss.cc b/net/ssl/client_cert_store_nss.cc
index 1b44bce92daf1c346137b8385aff5d8973cb555b..0f52fc79fd6cc926978d5842d6d8100490594627 100644
--- a/net/ssl/client_cert_store_nss.cc
+++ b/net/ssl/client_cert_store_nss.cc
@@ -123,11 +123,9 @@ void ClientCertStoreNSS::GetClientCertsOnWorkerThread(
       PR_FALSE,
       PR_FALSE,
       password_delegate.get());
-  // It is ok for a user not to have any client certs.
   if (!client_certs) {
     DVLOG(2) << "No client certs found.";
-    selected_certs->clear();
-    return;
+    client_certs = CERT_NewCertList();
   }
 
   GetClientCertsImpl(client_certs, *request, true, selected_certs);