Enable cert pinning for XMPP connection made by XmppClientSocketFactory.

jingle/glue/xmpp_client_socket_factory.cc

Index: jingle/glue/xmpp_client_socket_factory.cc
diff --git a/jingle/glue/xmpp_client_socket_factory.cc b/jingle/glue/xmpp_client_socket_factory.cc
index 13749e18332fcf1f465ea20573dc4dc8d8146e5b..b9e040d619fa01ca08a46887b6e6b13009e8dd5e 100644
--- a/jingle/glue/xmpp_client_socket_factory.cc
+++ b/jingle/glue/xmpp_client_socket_factory.cc
@@ -46,6 +46,9 @@ net::SSLClientSocket* XmppClientSocketFactory::CreateSSLClientSocket(
   net::SSLClientSocketContext context;
   context.cert_verifier =
       request_context_getter_->GetURLRequestContext()->cert_verifier();
+  context.transport_security_state = request_context_getter_->
+      GetURLRequestContext()->transport_security_state();
+  DCHECK(context.transport_security_state);
   // TODO(rkn): context.server_bound_cert_service is NULL because the
   // ServerBoundCertService class is not thread safe.
   return client_socket_factory_->CreateSSLClientSocket(