Negotiate use of RTCP loss notification feedback (LNTF)

When the LossNotifications field trial is in effect, LNTF should
be offered/accepted in the SDP message, not assumed to be configured
on both sides equally.

Bug: webrtc:10662
Change-Id: Ibd827779bd301821cbb4196857f6baebfc9e7dc2
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/138079
Commit-Queue: Elad Alon <eladalon@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28056}
diff --git a/test/call_config_utils.cc b/test/call_config_utils.cc
index af9ca11..155fad1 100644
--- a/test/call_config_utils.cc
+++ b/test/call_config_utils.cc
@@ -45,6 +45,7 @@
           : RtcpMode::kReducedSize;
   receive_config.rtp.remb = json["rtp"]["remb"].asBool();
   receive_config.rtp.transport_cc = json["rtp"]["transport_cc"].asBool();
+  receive_config.rtp.lntf.enabled = json["rtp"]["lntf"]["enabled"].asInt64();
   receive_config.rtp.nack.rtp_history_ms =
       json["rtp"]["nack"]["rtp_history_ms"].asInt64();
   receive_config.rtp.ulpfec_payload_type =
@@ -94,6 +95,7 @@
                               : "RtcpMode::kReducedSize";
   rtp_json["remb"] = config.rtp.remb;
   rtp_json["transport_cc"] = config.rtp.transport_cc;
+  rtp_json["lntf"]["enabled"] = config.rtp.lntf.enabled;
   rtp_json["nack"]["rtp_history_ms"] = config.rtp.nack.rtp_history_ms;
   rtp_json["ulpfec_payload_type"] = config.rtp.ulpfec_payload_type;
   rtp_json["red_payload_type"] = config.rtp.red_payload_type;