Don't report packets with id -1 to the transport feedback adapter as they provide no value.

webrtc/modules/congestion_controller/congestion_controller.cc

Index: webrtc/modules/congestion_controller/congestion_controller.cc
diff --git a/webrtc/modules/congestion_controller/congestion_controller.cc b/webrtc/modules/congestion_controller/congestion_controller.cc
index 44b2f41e86b85117b1e121ec6c56de1a028c29d4..bbdd968dc668f6c51587b891f700c96e39dbcc42 100644
--- a/webrtc/modules/congestion_controller/congestion_controller.cc
+++ b/webrtc/modules/congestion_controller/congestion_controller.cc
@@ -290,6 +290,10 @@ void CongestionController::SignalNetworkState(NetworkState state) {
 }
 
 void CongestionController::OnSentPacket(const rtc::SentPacket& sent_packet) {
+  // We're not interested in packets without an id, which may be stun packets,
+  // etc, sent on the same transport.
+  if (sent_packet.packet_id == -1)
+    return;
   transport_feedback_adapter_.OnSentPacket(sent_packet.packet_id,
                                            sent_packet.send_time_ms);
 }