Bug 1646092 - Do not add ssrc-group to sdp on recvonly msections; r=bwc

Chrome will not accept sdp with ssrc-group:FID on recvonly msections, causing
calls to fail to be established between Firefox and Chrome when only a
microphone is present on the Firefox side.

Differential Revision: https://phabricator.services.mozilla.com/D80034

media/webrtc/signaling/gtest/jsep_session_unittest.cpp

@@ -3085,11 +3085,7 @@ TEST_F(JsepSessionTest, OfferAnswerRecvOnlyLines) {
     const auto& msection =
         parsedOffer->GetMediaSection(transceiver->GetLevel());
     const auto& ssrcs = msection.GetAttributeList().GetSsrc().mSsrcs;
-    if (msection.GetMediaType() == SdpMediaSection::kVideo) {
-      ASSERT_EQ(2U, ssrcs.size());
-    } else {
-      ASSERT_EQ(1U, ssrcs.size());
-    }
+    ASSERT_EQ(1U, ssrcs.size());
   }
 }
 

media/webrtc/signaling/src/jsep/JsepTrack.cpp

@@ -256,8 +256,8 @@ bool JsepTrack::IsRtxEnabled(
 
 void JsepTrack::AddToMsection(const std::vector<JsConstraints>& constraintsList,
                               sdp::Direction direction,
-                              SsrcGenerator& ssrcGenerator,
-                              bool requireRtxSsrcs, SdpMediaSection* msection) {
+                              SsrcGenerator& ssrcGenerator, bool rtxEnabled,
+                              SdpMediaSection* msection) {
   UniquePtr<SdpSimulcastAttribute> simulcast(new SdpSimulcastAttribute);
   UniquePtr<SdpRidAttributeList> rids(new SdpRidAttributeList);
   for (const JsConstraints& constraints : constraintsList) {
@@ -283,6 +283,10 @@ void JsepTrack::AddToMsection(const std::vector<JsConstraints>& constraintsList,
     msection->GetAttributeList().SetAttribute(rids.release());
   }
 
+  bool requireRtxSsrcs =
+      rtxEnabled && msection->GetDirectionAttribute().mValue !=
+                        SdpDirectionAttribute::Direction::kRecvonly;
+
   if (mType != SdpMediaSection::kApplication && mDirection == sdp::kSend) {
     UpdateSsrcs(ssrcGenerator, constraintsList.size());
 

media/webrtc/signaling/src/jsep/JsepTrack.h

@@ -277,7 +277,7 @@ class JsepTrack {
 
   void AddToMsection(const std::vector<JsConstraints>& constraintsList,
                      sdp::Direction direction, SsrcGenerator& ssrcGenerator,
-                     bool requireRtxSsrcs, SdpMediaSection* msection);
+                     bool rtxEnabled, SdpMediaSection* msection);
 
   // See Bug 1642419, this can be removed when all sites are working with RTX.
   void SetRtxIsAllowed(bool aRtxIsAllowed) { mRtxIsAllowed = aRtxIsAllowed; }