Enable TURN on the host when using WebRTC.

remoting/protocol/webrtc_transport.cc

Index: remoting/protocol/webrtc_transport.cc
diff --git a/remoting/protocol/webrtc_transport.cc b/remoting/protocol/webrtc_transport.cc
index c342a121136fbea339ce8496f7211d8425fced6d..c1b703589fd502e64baa22c6aa50e77161ca35b1 100644
--- a/remoting/protocol/webrtc_transport.cc
+++ b/remoting/protocol/webrtc_transport.cc
@@ -119,7 +119,9 @@ WebrtcTransport::WebrtcTransport(
       incoming_data_stream_adapter_(
           false,
           base::Bind(&WebrtcTransport::Close, base::Unretained(this))),
-      weak_factory_(this) {}
+      weak_factory_(this) {
+  transport_context_->set_relay_mode(TransportContext::RelayMode::TURN);
+}
 
 WebrtcTransport::~WebrtcTransport() {}