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/sdk/objc/unittests/RTCSessionDescriptionTest.mm b/sdk/objc/unittests/RTCSessionDescriptionTest.mm
index 8a04a42..0807eed 100644
--- a/sdk/objc/unittests/RTCSessionDescriptionTest.mm
+++ b/sdk/objc/unittests/RTCSessionDescriptionTest.mm
@@ -60,71 +60,72 @@
 }
 
 - (NSString *)sdp {
-    return @"v=0\r\n"
-           "o=- 5319989746393411314 2 IN IP4 127.0.0.1\r\n"
-           "s=-\r\n"
-           "t=0 0\r\n"
-           "a=group:BUNDLE audio video\r\n"
-           "a=msid-semantic: WMS ARDAMS\r\n"
-           "m=audio 9 UDP/TLS/RTP/SAVPF 111 103 9 0 8 126\r\n"
-           "c=IN IP4 0.0.0.0\r\n"
-           "a=rtcp:9 IN IP4 0.0.0.0\r\n"
-           "a=ice-ufrag:f3o+0HG7l9nwIWFY\r\n"
-           "a=ice-pwd:VDctmJNCptR2TB7+meDpw7w5\r\n"
-           "a=fingerprint:sha-256 A9:D5:8D:A8:69:22:39:60:92:AD:94:1A:22:2D:5E:"
-           "A5:4A:A9:18:C2:35:5D:46:5E:59:BD:1C:AF:38:9F:E6:E1\r\n"
-           "a=setup:active\r\n"
-           "a=mid:audio\r\n"
-           "a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level\r\n"
-           "a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/"
-           "abs-send-time\r\n"
-           "a=sendrecv\r\n"
-           "a=rtcp-mux\r\n"
-           "a=rtpmap:111 opus/48000/2\r\n"
-           "a=fmtp:111 minptime=10;useinbandfec=1\r\n"
-           "a=rtpmap:103 ISAC/16000\r\n"
-           "a=rtpmap:9 G722/8000\r\n"
-           "a=rtpmap:0 PCMU/8000\r\n"
-           "a=rtpmap:8 PCMA/8000\r\n"
-           "a=rtpmap:126 telephone-event/8000\r\n"
-           "a=maxptime:60\r\n"
-           "a=ssrc:1504474588 cname:V+FdIC5AJpxLhdYQ\r\n"
-           "a=ssrc:1504474588 msid:ARDAMS ARDAMSa0\r\n"
-           "a=ssrc:1504474588 mslabel:ARDAMS\r\n"
-           "a=ssrc:1504474588 label:ARDAMSa0\r\n"
-           "m=video 9 UDP/TLS/RTP/SAVPF 100 116 117 96\r\n"
-           "c=IN IP4 0.0.0.0\r\n"
-           "a=rtcp:9 IN IP4 0.0.0.0\r\n"
-           "a=ice-ufrag:f3o+0HG7l9nwIWFY\r\n"
-           "a=ice-pwd:VDctmJNCptR2TB7+meDpw7w5\r\n"
-           "a=fingerprint:sha-256 A9:D5:8D:A8:69:22:39:60:92:AD:94:1A:22:2D:5E:"
-           "A5:4A:A9:18:C2:35:5D:46:5E:59:BD:1C:AF:38:9F:E6:E1\r\n"
-           "a=setup:active\r\n"
-           "a=mid:video\r\n"
-           "a=extmap:2 urn:ietf:params:rtp-hdrext:toffset\r\n"
-           "a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/"
-           "abs-send-time\r\n"
-           "a=extmap:4 urn:3gpp:video-orientation\r\n"
-           "a=sendrecv\r\n"
-           "a=rtcp-mux\r\n"
-           "a=rtpmap:100 VP8/90000\r\n"
-           "a=rtcp-fb:100 ccm fir\r\n"
-           "a=rtcp-fb:100 nack\r\n"
-           "a=rtcp-fb:100 nack pli\r\n"
-           "a=rtcp-fb:100 goog-remb\r\n"
-           "a=rtpmap:116 red/90000\r\n"
-           "a=rtpmap:117 ulpfec/90000\r\n"
-           "a=rtpmap:96 rtx/90000\r\n"
-           "a=fmtp:96 apt=100\r\n"
-           "a=ssrc-group:FID 498297514 1644357692\r\n"
-           "a=ssrc:498297514 cname:V+FdIC5AJpxLhdYQ\r\n"
-           "a=ssrc:498297514 msid:ARDAMS ARDAMSv0\r\n"
-           "a=ssrc:498297514 mslabel:ARDAMS\r\n"
-           "a=ssrc:498297514 label:ARDAMSv0\r\n"
-           "a=ssrc:1644357692 cname:V+FdIC5AJpxLhdYQ\r\n"
-           "a=ssrc:1644357692 msid:ARDAMS ARDAMSv0\r\n"
-           "a=ssrc:1644357692 mslabel:ARDAMS\r\n"
-           "a=ssrc:1644357692 label:ARDAMSv0\r\n";
+  return @"v=0\r\n"
+          "o=- 5319989746393411314 2 IN IP4 127.0.0.1\r\n"
+          "s=-\r\n"
+          "t=0 0\r\n"
+          "a=group:BUNDLE audio video\r\n"
+          "a=msid-semantic: WMS ARDAMS\r\n"
+          "m=audio 9 UDP/TLS/RTP/SAVPF 111 103 9 0 8 126\r\n"
+          "c=IN IP4 0.0.0.0\r\n"
+          "a=rtcp:9 IN IP4 0.0.0.0\r\n"
+          "a=ice-ufrag:f3o+0HG7l9nwIWFY\r\n"
+          "a=ice-pwd:VDctmJNCptR2TB7+meDpw7w5\r\n"
+          "a=fingerprint:sha-256 A9:D5:8D:A8:69:22:39:60:92:AD:94:1A:22:2D:5E:"
+          "A5:4A:A9:18:C2:35:5D:46:5E:59:BD:1C:AF:38:9F:E6:E1\r\n"
+          "a=setup:active\r\n"
+          "a=mid:audio\r\n"
+          "a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level\r\n"
+          "a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/"
+          "abs-send-time\r\n"
+          "a=sendrecv\r\n"
+          "a=rtcp-mux\r\n"
+          "a=rtpmap:111 opus/48000/2\r\n"
+          "a=fmtp:111 minptime=10;useinbandfec=1\r\n"
+          "a=rtpmap:103 ISAC/16000\r\n"
+          "a=rtpmap:9 G722/8000\r\n"
+          "a=rtpmap:0 PCMU/8000\r\n"
+          "a=rtpmap:8 PCMA/8000\r\n"
+          "a=rtpmap:126 telephone-event/8000\r\n"
+          "a=maxptime:60\r\n"
+          "a=ssrc:1504474588 cname:V+FdIC5AJpxLhdYQ\r\n"
+          "a=ssrc:1504474588 msid:ARDAMS ARDAMSa0\r\n"
+          "a=ssrc:1504474588 mslabel:ARDAMS\r\n"
+          "a=ssrc:1504474588 label:ARDAMSa0\r\n"
+          "m=video 9 UDP/TLS/RTP/SAVPF 100 116 117 96\r\n"
+          "c=IN IP4 0.0.0.0\r\n"
+          "a=rtcp:9 IN IP4 0.0.0.0\r\n"
+          "a=ice-ufrag:f3o+0HG7l9nwIWFY\r\n"
+          "a=ice-pwd:VDctmJNCptR2TB7+meDpw7w5\r\n"
+          "a=fingerprint:sha-256 A9:D5:8D:A8:69:22:39:60:92:AD:94:1A:22:2D:5E:"
+          "A5:4A:A9:18:C2:35:5D:46:5E:59:BD:1C:AF:38:9F:E6:E1\r\n"
+          "a=setup:active\r\n"
+          "a=mid:video\r\n"
+          "a=extmap:2 urn:ietf:params:rtp-hdrext:toffset\r\n"
+          "a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/"
+          "abs-send-time\r\n"
+          "a=extmap:4 urn:3gpp:video-orientation\r\n"
+          "a=sendrecv\r\n"
+          "a=rtcp-mux\r\n"
+          "a=rtpmap:100 VP8/90000\r\n"
+          "a=rtcp-fb:100 ccm fir\r\n"
+          "a=rtcp-fb:100 goog-lntf\r\n"
+          "a=rtcp-fb:100 nack\r\n"
+          "a=rtcp-fb:100 nack pli\r\n"
+          "a=rtcp-fb:100 goog-remb\r\n"
+          "a=rtpmap:116 red/90000\r\n"
+          "a=rtpmap:117 ulpfec/90000\r\n"
+          "a=rtpmap:96 rtx/90000\r\n"
+          "a=fmtp:96 apt=100\r\n"
+          "a=ssrc-group:FID 498297514 1644357692\r\n"
+          "a=ssrc:498297514 cname:V+FdIC5AJpxLhdYQ\r\n"
+          "a=ssrc:498297514 msid:ARDAMS ARDAMSv0\r\n"
+          "a=ssrc:498297514 mslabel:ARDAMS\r\n"
+          "a=ssrc:498297514 label:ARDAMSv0\r\n"
+          "a=ssrc:1644357692 cname:V+FdIC5AJpxLhdYQ\r\n"
+          "a=ssrc:1644357692 msid:ARDAMS ARDAMSv0\r\n"
+          "a=ssrc:1644357692 mslabel:ARDAMS\r\n"
+          "a=ssrc:1644357692 label:ARDAMSv0\r\n";
 }
 
 @end