Bug 1829667: Make JsepTransceiver non-refcounted. r=mjf,webidl,mccr8

Involves substantial refactoring to make most access by-value (or through
functional-style in-place modifications) for safety.

Differential Revision: https://phabricator.services.mozilla.com/D176423

dom/media/PeerConnection.sys.mjs

@@ -1391,11 +1391,14 @@ export class RTCPeerConnection {
         transceiver.setDirectionInternal("sendonly");
       }
     } else {
-      transceiver = this._addTransceiverNoEvents(track, {
+      transceiver = this._addTransceiverNoEvents(
+        track,
+        {
           streams,
           direction: "sendrecv",
-      });
+        },
-      transceiver.setAddTrackMagic();
+        true
+      );
     }
 
     this.updateNegotiationNeeded();
@@ -1431,7 +1434,7 @@ export class RTCPeerConnection {
     this.updateNegotiationNeeded();
   }
 
-  _addTransceiverNoEvents(sendTrackOrKind, init) {
+  _addTransceiverNoEvents(sendTrackOrKind, init, addTrackMagic) {
     let sendTrack = null;
     let kind;
     if (typeof sendTrackOrKind == "string") {
@@ -1449,7 +1452,7 @@ export class RTCPeerConnection {
     }
 
     try {
-      return this._pc.addTransceiver(init, kind, sendTrack);
+      return this._pc.addTransceiver(init, kind, sendTrack, addTrackMagic);
     } catch (e) {
       // Exceptions thrown by c++ code do not propagate. In most cases, that's
       // fine because we're using Promises, which can be copied. But this is

dom/media/webrtc/jsapi/PeerConnectionImpl.cpp

@@ -877,17 +877,14 @@ nsresult PeerConnectionImpl::GetDatachannelParameters(
   *mmsset = false;
   transportId->clear();
 
-  RefPtr<JsepTransceiver> datachannelTransceiver;
+  Maybe<const JsepTransceiver> datachannelTransceiver =
-  for (const auto& transceiver : mJsepSession->GetTransceivers()) {
+      mJsepSession->FindTransceiver([](const JsepTransceiver& aTransceiver) {
-    if ((transceiver->GetMediaType() == SdpMediaSection::kApplication) &&
+        return aTransceiver.GetMediaType() == SdpMediaSection::kApplication;
-        transceiver->mSendTrack.GetNegotiatedDetails()) {
+      });
-      datachannelTransceiver = transceiver;
-      break;
-    }
-  }
 
   if (!datachannelTransceiver ||
-      !datachannelTransceiver->mTransport.mComponents) {
+      !datachannelTransceiver->mTransport.mComponents ||
+      !datachannelTransceiver->mSendTrack.GetNegotiatedDetails()) {
     return NS_ERROR_FAILURE;
   }
 
@@ -942,7 +939,7 @@ nsresult PeerConnectionImpl::GetDatachannelParameters(
 }
 
 nsresult PeerConnectionImpl::AddRtpTransceiverToJsepSession(
-    RefPtr<JsepTransceiver>& transceiver) {
+    JsepTransceiver& transceiver) {
   nsresult res = ConfigureJsepSessionCodecs();
   if (NS_FAILED(res)) {
     CSFLogError(LOGTAG, "Failed to configure codecs");
@@ -965,7 +962,7 @@ static Maybe<SdpMediaSection::MediaType> ToSdpMediaType(
 
 already_AddRefed<RTCRtpTransceiver> PeerConnectionImpl::AddTransceiver(
     const dom::RTCRtpTransceiverInit& aInit, const nsAString& aKind,
-    dom::MediaStreamTrack* aSendTrack, ErrorResult& aRv) {
+    dom::MediaStreamTrack* aSendTrack, bool aAddTrackMagic, ErrorResult& aRv) {
   // Copy, because we might need to modify
   RTCRtpTransceiverInit init(aInit);
 
@@ -976,9 +973,8 @@ already_AddRefed<RTCRtpTransceiver> PeerConnectionImpl::AddTransceiver(
     return nullptr;
   }
 
-  RefPtr<JsepTransceiver> jsepTransceiver =
+  JsepTransceiver jsepTransceiver(*type, *mUuidGen);
-      new JsepTransceiver(*type, *mUuidGen);
+  jsepTransceiver.SetRtxIsAllowed(mRtxIsAllowed);
-  jsepTransceiver->SetRtxIsAllowed(mRtxIsAllowed);
 
   // Do this last, since it is not possible to roll back.
   nsresult rv = AddRtpTransceiverToJsepSession(jsepTransceiver);
@@ -1074,9 +1070,9 @@ already_AddRefed<RTCRtpTransceiver> PeerConnectionImpl::AddTransceiver(
   }
 
   RefPtr<RTCRtpTransceiver> transceiver = CreateTransceiver(
-      jsepTransceiver->GetUuid(),
+      jsepTransceiver.GetUuid(),
-      jsepTransceiver->GetMediaType() == SdpMediaSection::kVideo, init,
+      jsepTransceiver.GetMediaType() == SdpMediaSection::kVideo, init,
-      aSendTrack, aRv);
+      aSendTrack, aAddTrackMagic, aRv);
 
   if (aRv.Failed()) {
     // Would be nice if we could peek at the rv without stealing it, so we
@@ -1177,21 +1173,18 @@ PeerConnectionImpl::CreateDataChannel(
 
   CSFLogDebug(LOGTAG, "%s: making DOMDataChannel", __FUNCTION__);
 
-  RefPtr<JsepTransceiver> dcTransceiver;
+  Maybe<JsepTransceiver> dcTransceiver =
-  for (auto& transceiver : mJsepSession->GetTransceivers()) {
+      mJsepSession->FindTransceiver([](const JsepTransceiver& aTransceiver) {
-    if (transceiver->GetMediaType() == SdpMediaSection::kApplication) {
+        return aTransceiver.GetMediaType() == SdpMediaSection::kApplication;
-      dcTransceiver = transceiver;
+      });
-      break;
-    }
-  }
-
-  if (!dcTransceiver) {
-    dcTransceiver = new JsepTransceiver(
-        SdpMediaSection::MediaType::kApplication, *mUuidGen);
-    mJsepSession->AddTransceiver(dcTransceiver);
-  }
 
+  if (dcTransceiver) {
     dcTransceiver->RestartDatachannelTransceiver();
+    mJsepSession->SetTransceiver(*dcTransceiver);
+  } else {
+    mJsepSession->AddTransceiver(
+        JsepTransceiver(SdpMediaSection::MediaType::kApplication, *mUuidGen));
+  }
 
   RefPtr<nsDOMDataChannel> retval;
   rv = NS_NewDOMDataChannel(dataChannel.forget(), mWindow,
@@ -1364,22 +1357,24 @@ void PeerConnectionImpl::RunNextOperation(ErrorResult& aError) {
 
 void PeerConnectionImpl::SyncToJsep() {
   for (const auto& transceiver : mTransceivers) {
-    transceiver->SyncToJsep();
+    transceiver->SyncToJsep(*mJsepSession);
   }
 }
 
 void PeerConnectionImpl::SyncFromJsep() {
   CSFLogDebug(LOGTAG, "%s", __FUNCTION__);
-  for (const auto& jsepTransceiver : mJsepSession->GetTransceivers()) {
+  mJsepSession->ForEachTransceiver(
-    if (jsepTransceiver->GetMediaType() ==
+      [this, self = RefPtr<PeerConnectionImpl>(this)](
+          const JsepTransceiver& jsepTransceiver) {
+        if (jsepTransceiver.GetMediaType() ==
             SdpMediaSection::MediaType::kApplication) {
-      continue;
+          return;
         }
 
         CSFLogDebug(LOGTAG, "%s: Looking for match", __FUNCTION__);
         RefPtr<RTCRtpTransceiver> transceiver;
         for (auto& temp : mTransceivers) {
-      if (temp->GetJsepTransceiverId() == jsepTransceiver->GetUuid()) {
+          if (temp->GetJsepTransceiverId() == jsepTransceiver.GetUuid()) {
             CSFLogDebug(LOGTAG, "%s: Found match", __FUNCTION__);
             transceiver = temp;
             break;
@@ -1392,9 +1387,9 @@ void PeerConnectionImpl::SyncFromJsep() {
           init.mDirection = RTCRtpTransceiverDirection::Recvonly;
           IgnoredErrorResult rv;
           transceiver = CreateTransceiver(
-          jsepTransceiver->GetUuid(),
+              jsepTransceiver.GetUuid(),
-          jsepTransceiver->GetMediaType() == SdpMediaSection::kVideo, init,
+              jsepTransceiver.GetMediaType() == SdpMediaSection::kVideo, init,
-          nullptr, rv);
+              nullptr, false, rv);
           if (NS_WARN_IF(rv.Failed())) {
             MOZ_ASSERT(false);
             return;
@@ -1403,8 +1398,8 @@ void PeerConnectionImpl::SyncFromJsep() {
         }
 
         CSFLogDebug(LOGTAG, "%s: Syncing transceiver", __FUNCTION__);
-    transceiver->SyncFromJsep();
+        transceiver->SyncFromJsep(*mJsepSession);
-  }
+      });
 }
 
 already_AddRefed<dom::Promise> PeerConnectionImpl::MakePromise(
@@ -1592,9 +1587,6 @@ PeerConnectionImpl::CreateOffer(const JsepOfferOptions& aOptions) {
               *buildJSErrorData(result, errorString), rv);
         } else {
           mJsepSession = std::move(uncommittedJsepSession);
-          for (auto& transceiver : mTransceivers) {
-            transceiver->SetJsepSession(mJsepSession.get());
-          }
           mPCObserver->OnCreateOfferSuccess(ObString(offer.c_str()), rv);
         }
       }));
@@ -1631,9 +1623,6 @@ PeerConnectionImpl::CreateAnswer() {
               *buildJSErrorData(result, errorString), rv);
         } else {
           mJsepSession = std::move(uncommittedJsepSession);
-          for (auto& transceiver : mTransceivers) {
-            transceiver->SetJsepSession(mJsepSession.get());
-          }
           mPCObserver->OnCreateAnswerSuccess(ObString(answer.c_str()), rv);
         }
       }));
@@ -3012,9 +3001,6 @@ void PeerConnectionImpl::DoSetDescriptionSuccessPostProcessing(
         }
 
         mJsepSession = std::move(mUncommittedJsepSession);
-        for (auto& transceiver : mTransceivers) {
-          transceiver->SetJsepSession(mJsepSession.get());
-        }
 
         auto newSignalingState = GetSignalingState();
         SyncFromJsep();
@@ -3981,30 +3967,33 @@ bool PeerConnectionImpl::ShouldForceProxy() const {
 }
 
 void PeerConnectionImpl::EnsureTransports(const JsepSession& aSession) {
-  for (const auto& transceiver : aSession.GetTransceivers()) {
+  mJsepSession->ForEachTransceiver([this,
-    if (transceiver->HasOwnTransport()) {
+                                    self = RefPtr<PeerConnectionImpl>(this)](
+                                       const JsepTransceiver& transceiver) {
+    if (transceiver.HasOwnTransport()) {
       mTransportHandler->EnsureProvisionalTransport(
-          transceiver->mTransport.mTransportId,
+          transceiver.mTransport.mTransportId,
-          transceiver->mTransport.mLocalUfrag,
+          transceiver.mTransport.mLocalUfrag, transceiver.mTransport.mLocalPwd,
-          transceiver->mTransport.mLocalPwd,
+          transceiver.mTransport.mComponents);
-          transceiver->mTransport.mComponents);
-    }
     }
+  });
 
   GatherIfReady();
 }
 
 void PeerConnectionImpl::UpdateRTCDtlsTransports(bool aMarkAsStable) {
-  for (const auto& jsepTransceiver : mJsepSession->GetTransceivers()) {
+  mJsepSession->ForEachTransceiver(
-    std::string transportId = jsepTransceiver->mTransport.mTransportId;
+      [this, self = RefPtr<PeerConnectionImpl>(this)](
+          const JsepTransceiver& jsepTransceiver) {
+        std::string transportId = jsepTransceiver.mTransport.mTransportId;
         if (transportId.empty()) {
-      continue;
+          return;
         }
         if (!mTransportIdToRTCDtlsTransport.count(transportId)) {
           mTransportIdToRTCDtlsTransport.emplace(
               transportId, new RTCDtlsTransport(GetParentObject()));
         }
-  }
+      });
 
   for (auto& transceiver : mTransceivers) {
     std::string transportId = transceiver->GetTransportId();
@@ -4042,17 +4031,19 @@ nsresult PeerConnectionImpl::UpdateTransports(const JsepSession& aSession,
                                               const bool forceIceTcp) {
   std::set<std::string> finalTransports;
   Maybe<std::string> sctpTransport;
-  for (const auto& transceiver : aSession.GetTransceivers()) {
+  mJsepSession->ForEachTransceiver(
-    if (transceiver->GetMediaType() == SdpMediaSection::kApplication &&
+      [&, this, self = RefPtr<PeerConnectionImpl>(this)](
-        transceiver->HasTransport()) {
+          const JsepTransceiver& transceiver) {
-      sctpTransport = Some(transceiver->mTransport.mTransportId);
+        if (transceiver.GetMediaType() == SdpMediaSection::kApplication &&
+            transceiver.HasTransport()) {
+          sctpTransport = Some(transceiver.mTransport.mTransportId);
         }
 
-    if (transceiver->HasOwnTransport()) {
+        if (transceiver.HasOwnTransport()) {
-      finalTransports.insert(transceiver->mTransport.mTransportId);
+          finalTransports.insert(transceiver.mTransport.mTransportId);
-      UpdateTransport(*transceiver, forceIceTcp);
+          UpdateTransport(transceiver, forceIceTcp);
-    }
         }
+      });
 
   // clean up the unused RTCDtlsTransports
   RemoveRTCDtlsTransportsExcept(finalTransports);
@@ -4447,7 +4438,7 @@ void PeerConnectionImpl::EnsureIceGathering(bool aDefaultRouteOnly,
 
 already_AddRefed<dom::RTCRtpTransceiver> PeerConnectionImpl::CreateTransceiver(
     const std::string& aId, bool aIsVideo, const RTCRtpTransceiverInit& aInit,
-    dom::MediaStreamTrack* aSendTrack, ErrorResult& aRv) {
+    dom::MediaStreamTrack* aSendTrack, bool aAddTrackMagic, ErrorResult& aRv) {
   PeerConnectionCtx* ctx = PeerConnectionCtx::GetInstance();
   if (!mCall) {
     mCall = WebrtcCallWrapper::Create(
@@ -4458,6 +4449,12 @@ already_AddRefed<dom::RTCRtpTransceiver> PeerConnectionImpl::CreateTransceiver(
         ctx->GetSharedWebrtcState());
   }
 
+  if (aAddTrackMagic) {
+    mJsepSession->ApplyToTransceiver(aId, [](JsepTransceiver& aTransceiver) {
+      aTransceiver.SetAddTrackMagic();
+    });
+  }
+
   RefPtr<RTCRtpTransceiver> transceiver = new RTCRtpTransceiver(
       mWindow, PrivacyRequested(), this, mTransportHandler, mJsepSession.get(),
       aId, aIsVideo, mSTSThread.get(), aSendTrack, mCall.get(), mIdGenerator);
@@ -4467,8 +4464,6 @@ already_AddRefed<dom::RTCRtpTransceiver> PeerConnectionImpl::CreateTransceiver(
     return nullptr;
   }
 
-  transceiver->SyncToJsep();
-
   if (aSendTrack) {
     // implement checking for peerIdentity (where failure == black/silence)
     Document* doc = mWindow->GetExtantDoc();

dom/media/webrtc/jsapi/PeerConnectionImpl.h

@@ -296,7 +296,7 @@ class PeerConnectionImpl final
 
   already_AddRefed<dom::RTCRtpTransceiver> AddTransceiver(
       const dom::RTCRtpTransceiverInit& aInit, const nsAString& aKind,
-      dom::MediaStreamTrack* aSendTrack, ErrorResult& aRv);
+      dom::MediaStreamTrack* aSendTrack, bool aAddTrackMagic, ErrorResult& aRv);
 
   bool CheckNegotiationNeeded();
   bool CreatedSender(const dom::RTCRtpSender& aSender) const;
@@ -614,7 +614,7 @@ class PeerConnectionImpl final
                                     std::string* transportId,
                                     bool* client) const;
 
-  nsresult AddRtpTransceiverToJsepSession(RefPtr<JsepTransceiver>& transceiver);
+  nsresult AddRtpTransceiverToJsepSession(JsepTransceiver& transceiver);
 
   void RecordIceRestartStatistics(JsepSdpType type);
 
@@ -825,7 +825,7 @@ class PeerConnectionImpl final
   already_AddRefed<dom::RTCRtpTransceiver> CreateTransceiver(
       const std::string& aId, bool aIsVideo,
       const dom::RTCRtpTransceiverInit& aInit,
-      dom::MediaStreamTrack* aSendTrack, ErrorResult& aRv);
+      dom::MediaStreamTrack* aSendTrack, bool aAddTrackMagic, ErrorResult& aRv);
 
   std::string GetTransportIdMatchingSendTrack(
       const dom::MediaStreamTrack& aTrack) const;

dom/media/webrtc/jsapi/RTCRtpReceiver.cpp

@@ -892,12 +892,12 @@ std::string RTCRtpReceiver::GetMid() const {
 
 JsepTransceiver& RTCRtpReceiver::GetJsepTransceiver() {
   MOZ_ASSERT(mTransceiver);
-  return *mTransceiver->GetJsepTransceiver();
+  return mTransceiver->GetJsepTransceiver();
 }
 
 const JsepTransceiver& RTCRtpReceiver::GetJsepTransceiver() const {
   MOZ_ASSERT(mTransceiver);
-  return *mTransceiver->GetJsepTransceiver();
+  return mTransceiver->GetJsepTransceiver();
 }
 
 }  // namespace mozilla::dom

dom/media/webrtc/jsapi/RTCRtpSender.cpp

@@ -74,10 +74,6 @@ RTCRtpSender::RTCRtpSender(nsPIDOMWindowInner* aWindow, PeerConnectionImpl* aPc,
 
   if (aConduit->type() == MediaSessionConduit::AUDIO) {
     mDtmf = new RTCDTMFSender(aWindow, mTransceiver);
-    GetJsepTransceiver().mSendTrack.SetMaxEncodings(1);
-  } else {
-    GetJsepTransceiver().mSendTrack.SetMaxEncodings(
-        webrtc::kMaxSimulcastStreams);
   }
   mPipeline->SetTrack(mSenderTrack);
 
@@ -91,7 +87,7 @@ RTCRtpSender::RTCRtpSender(nsPIDOMWindowInner* aWindow, PeerConnectionImpl* aPc,
   if (aEncodings.Length()) {
     // This sender was created by addTransceiver with sendEncodings.
     mParameters.mEncodings = aEncodings;
-    SetJsepRids(mParameters);
+    mSimulcastEnvelopeSet = true;
     mozilla::glean::rtcrtpsender::used_sendencodings.AddToNumerator(1);
   } else {
     // This sender was created by addTrack, sRD(offer), or addTransceiver
@@ -724,7 +720,7 @@ already_AddRefed<Promise> RTCRtpSender::SetParameters(
   MaybeUpdateConduit();
 
   if (compatModeAllowedRidChange) {
-    SetJsepRids(paramsCopy);
+    mSimulcastEnvelopeSet = true;
   }
 
   // If the media stack is successfully configured with parameters,
@@ -841,22 +837,6 @@ void RTCRtpSender::CheckAndRectifyEncodings(
   }
 }
 
-void RTCRtpSender::SetJsepRids(const RTCRtpSendParameters& aParameters) {
-  MOZ_ASSERT(aParameters.mEncodings.Length());
-
-  std::vector<std::string> rids;
-  for (const auto& encoding : aParameters.mEncodings) {
-    if (encoding.mRid.WasPassed()) {
-      rids.push_back(NS_ConvertUTF16toUTF8(encoding.mRid.Value()).get());
-    } else {
-      rids.push_back("");
-    }
-  }
-
-  GetJsepTransceiver().mSendTrack.SetRids(rids);
-  mSimulcastEnvelopeSet = true;
-}
-
 void RTCRtpSender::GetParameters(RTCRtpSendParameters& aParameters) {
   MOZ_ASSERT(mParameters.mEncodings.Length());
   // If sender.[[LastReturnedParameters]] is not null, return
@@ -1206,10 +1186,10 @@ void RTCRtpSender::SetTrack(const RefPtr<MediaStreamTrack>& aTrack) {
   mSenderTrack = aTrack;
   SeamlessTrackSwitch(aTrack);
   if (aTrack) {
-    // RFC says:
+    // RFC says (in the section on remote rollback):
     // However, an RtpTransceiver MUST NOT be removed if a track was attached
     // to the RtpTransceiver via the addTrack method.
-    GetJsepTransceiver().SetOnlyExistsBecauseOfSetRemote(false);
+    mAddTrackCalled = true;
   }
 }
 
@@ -1314,6 +1294,29 @@ void RTCRtpSender::SyncToJsep(JsepTransceiver& aJsepTransceiver) const {
   }
 
   aJsepTransceiver.mSendTrack.UpdateStreamIds(streamIds);
+
+  if (mSimulcastEnvelopeSet) {
+    std::vector<std::string> rids;
+    for (const auto& encoding : mParameters.mEncodings) {
+      if (encoding.mRid.WasPassed()) {
+        rids.push_back(NS_ConvertUTF16toUTF8(encoding.mRid.Value()).get());
+      } else {
+        rids.push_back("");
+      }
+    }
+
+    aJsepTransceiver.mSendTrack.SetRids(rids);
+  }
+
+  if (mTransceiver->IsVideo()) {
+    aJsepTransceiver.mSendTrack.SetMaxEncodings(webrtc::kMaxSimulcastStreams);
+  } else {
+    aJsepTransceiver.mSendTrack.SetMaxEncodings(1);
+  }
+
+  if (mAddTrackCalled) {
+    aJsepTransceiver.SetOnlyExistsBecauseOfSetRemote(false);
+  }
 }
 
 Maybe<RTCRtpSender::VideoConfig> RTCRtpSender::GetNewVideoConfig() {
@@ -1579,7 +1582,7 @@ RefPtr<MediaPipelineTransmit> RTCRtpSender::GetPipeline() const {
 std::string RTCRtpSender::GetMid() const { return mTransceiver->GetMidAscii(); }
 
 JsepTransceiver& RTCRtpSender::GetJsepTransceiver() {
-  return *mTransceiver->GetJsepTransceiver();
+  return mTransceiver->GetJsepTransceiver();
 }
 
 void RTCRtpSender::UpdateDtmfSender() {

dom/media/webrtc/jsapi/RTCRtpSender.h

@@ -138,7 +138,6 @@ class RTCRtpSender : public nsISupports,
 
   std::string GetMid() const;
   JsepTransceiver& GetJsepTransceiver();
-  void SetJsepRids(const RTCRtpSendParameters& aParameters);
   static void ApplyJsEncodingToConduitEncoding(
       const RTCRtpEncodingParameters& aJsEncoding,
       VideoCodecConfig::Encoding* aConduitEncoding);
@@ -157,6 +156,7 @@ class RTCRtpSender : public nsISupports,
   nsCOMPtr<nsPIDOMWindowInner> mWindow;
   RefPtr<PeerConnectionImpl> mPc;
   RefPtr<dom::MediaStreamTrack> mSenderTrack;
+  bool mAddTrackCalled = false;
   RTCRtpSendParameters mParameters;
   Maybe<RTCRtpSendParameters> mPendingParameters;
   uint32_t mNumSetParametersCalls = 0;

dom/media/webrtc/jsapi/RTCRtpTransceiver.cpp

@@ -164,7 +164,7 @@ RTCRtpTransceiver::RTCRtpTransceiver(
       mPc(aPc),
       mTransportHandler(aTransportHandler),
       mTransceiverId(aTransceiverId),
-      mJsepTransceiver(aJsepSession->GetTransceiver(mTransceiverId)),
+      mJsepTransceiver(*aJsepSession->GetTransceiver(mTransceiverId)),
       mStsThread(aStsThread),
       mCallWrapper(aCallWrapper),
       mSendTrack(aSendTrack),
@@ -449,7 +449,7 @@ bool RTCRtpTransceiver::ConduitHasPluginID(uint64_t aPluginID) {
   return mConduit && mConduit->HasCodecPluginID(aPluginID);
 }
 
-void RTCRtpTransceiver::SyncFromJsep() {
+void RTCRtpTransceiver::SyncFromJsep(const JsepSession& aSession) {
   MOZ_MTLOG(ML_DEBUG, mPc->GetHandle()
                           << "[" << mMid.Ref() << "]: " << __FUNCTION__
                           << " Syncing from JSEP transceiver");
@@ -459,35 +459,35 @@ void RTCRtpTransceiver::SyncFromJsep() {
     return;
   }
 
-  auto jsepTransceiver = GetJsepTransceiver();
+  mJsepTransceiver = *aSession.GetTransceiver(mTransceiverId);
 
   // Transceivers can stop due to JSEP negotiation, so we need to check that
-  if (jsepTransceiver->IsStopped()) {
+  if (mJsepTransceiver.IsStopped()) {
     StopImpl();
   }
 
-  mReceiver->SyncFromJsep(*jsepTransceiver);
+  mReceiver->SyncFromJsep(mJsepTransceiver);
-  mSender->SyncFromJsep(*jsepTransceiver);
+  mSender->SyncFromJsep(mJsepTransceiver);
 
   // mid from JSEP
-  if (jsepTransceiver->IsAssociated()) {
+  if (mJsepTransceiver.IsAssociated()) {
-    mMid = jsepTransceiver->GetMid();
+    mMid = mJsepTransceiver.GetMid();
   } else {
     mMid = std::string();
   }
 
   // currentDirection from JSEP, but not if "this transceiver has never been
   // represented in an offer/answer exchange"
-  if (jsepTransceiver->HasLevel() && jsepTransceiver->IsNegotiated()) {
+  if (mJsepTransceiver.HasLevel() && mJsepTransceiver.IsNegotiated()) {
-    if (jsepTransceiver->mRecvTrack.GetActive()) {
+    if (mJsepTransceiver.mRecvTrack.GetActive()) {
-      if (jsepTransceiver->mSendTrack.GetActive()) {
+      if (mJsepTransceiver.mSendTrack.GetActive()) {
         mCurrentDirection.SetValue(dom::RTCRtpTransceiverDirection::Sendrecv);
         mHasBeenUsedToSend = true;
       } else {
         mCurrentDirection.SetValue(dom::RTCRtpTransceiverDirection::Recvonly);
       }
     } else {
-      if (jsepTransceiver->mSendTrack.GetActive()) {
+      if (mJsepTransceiver.mSendTrack.GetActive()) {
         mCurrentDirection.SetValue(dom::RTCRtpTransceiverDirection::Sendonly);
         mHasBeenUsedToSend = true;
       } else {
@@ -496,28 +496,25 @@ void RTCRtpTransceiver::SyncFromJsep() {
     }
   }
 
-  mShouldRemove = jsepTransceiver->IsRemoved();
+  mShouldRemove = mJsepTransceiver.IsRemoved();
-  mHasTransport = jsepTransceiver->HasLevel() && !jsepTransceiver->IsStopped();
+  mHasTransport = mJsepTransceiver.HasLevel() && !mJsepTransceiver.IsStopped();
 }
 
-void RTCRtpTransceiver::SyncToJsep() const {
+void RTCRtpTransceiver::SyncToJsep(JsepSession& aSession) const {
   MOZ_MTLOG(ML_DEBUG, mPc->GetHandle()
                           << "[" << mMid.Ref() << "]: " << __FUNCTION__
                           << " Syncing to JSEP transceiver");
 
-  auto jsepTransceiver = GetJsepTransceiver();
+  aSession.ApplyToTransceiver(
-  mReceiver->SyncToJsep(*jsepTransceiver);
+      mTransceiverId, [this, self = RefPtr<const RTCRtpTransceiver>(this)](
-  mSender->SyncToJsep(*jsepTransceiver);
+                          JsepTransceiver& aTransceiver) {
-  jsepTransceiver->mJsDirection = ToSdpDirection(mDirection);
+        mReceiver->SyncToJsep(aTransceiver);
+        mSender->SyncToJsep(aTransceiver);
+        aTransceiver.mJsDirection = ToSdpDirection(mDirection);
         if (mStopped) {
-    jsepTransceiver->Stop();
+          aTransceiver.Stop();
         }
-}
+      });
-
-// TODO: Unify with SyncFromJsep
-void RTCRtpTransceiver::SetJsepSession(JsepSession* aJsepSession) {
-  mJsepTransceiver = aJsepSession->GetTransceiver(mTransceiverId);
-  MOZ_RELEASE_ASSERT(mJsepTransceiver);
 }
 
 void RTCRtpTransceiver::GetKind(nsAString& aKind) const {
@@ -565,12 +562,6 @@ void RTCRtpTransceiver::SetDirectionInternal(
   mDirection = aDirection;
 }
 
-void RTCRtpTransceiver::SetAddTrackMagic() {
-  // We do this immediately, without waiting for a SyncToJsep, because this is
-  // set at transceiver creation time.
-  GetJsepTransceiver()->SetAddTrackMagic();
-}
-
 bool RTCRtpTransceiver::ShouldRemove() const { return mShouldRemove; }
 
 bool RTCRtpTransceiver::CanSendDTMF() const {
@@ -589,8 +580,8 @@ bool RTCRtpTransceiver::CanSendDTMF() const {
 
   // Ok, it looks like the connection is up and sending. Did we negotiate
   // telephone-event?
-  JsepTrackNegotiatedDetails* details =
+  const JsepTrackNegotiatedDetails* details =
-      GetJsepTransceiver()->mSendTrack.GetNegotiatedDetails();
+      mJsepTransceiver.mSendTrack.GetNegotiatedDetails();
   if (NS_WARN_IF(!details || !details->GetEncodingCount())) {
     // What?
     return false;
@@ -648,12 +639,11 @@ static void JsepCodecDescToAudioCodecConfig(
 // TODO: This and the next function probably should move to JsepTransceiver
 Maybe<const std::vector<UniquePtr<JsepCodecDescription>>&>
 RTCRtpTransceiver::GetNegotiatedSendCodecs() const {
-  auto jsepTransceiver = GetJsepTransceiver();
+  if (!mJsepTransceiver.mSendTrack.GetActive()) {
-  if (!jsepTransceiver->mSendTrack.GetActive()) {
     return Nothing();
   }
 
-  const auto* details = jsepTransceiver->mSendTrack.GetNegotiatedDetails();
+  const auto* details = mJsepTransceiver.mSendTrack.GetNegotiatedDetails();
   if (!details) {
     return Nothing();
   }
@@ -667,12 +657,11 @@ RTCRtpTransceiver::GetNegotiatedSendCodecs() const {
 
 Maybe<const std::vector<UniquePtr<JsepCodecDescription>>&>
 RTCRtpTransceiver::GetNegotiatedRecvCodecs() const {
-  auto jsepTransceiver = GetJsepTransceiver();
+  if (!mJsepTransceiver.mRecvTrack.GetActive()) {
-  if (!jsepTransceiver->mRecvTrack.GetActive()) {
     return Nothing();
   }
 
-  const auto* details = jsepTransceiver->mRecvTrack.GetNegotiatedDetails();
+  const auto* details = mJsepTransceiver.mRecvTrack.GetNegotiatedDetails();
   if (!details) {
     return Nothing();
   }

dom/media/webrtc/jsapi/RTCRtpTransceiver.h

@@ -102,25 +102,21 @@ class RTCRtpTransceiver : public nsISupports, public nsWrapperCache {
   void Stop(ErrorResult& aRv);
   void SetDirectionInternal(RTCRtpTransceiverDirection aDirection);
   bool HasBeenUsedToSend() const { return mHasBeenUsedToSend; }
-  void SetAddTrackMagic();
 
   bool CanSendDTMF() const;
   bool Stopped() const { return mStopped; }
-  void SyncToJsep() const;
+  void SyncToJsep(JsepSession& aSession) const;
-  void SyncFromJsep();
+  void SyncFromJsep(const JsepSession& aSession);
-  void SetJsepSession(JsepSession* aJsepSession);
   std::string GetMidAscii() const;
 
   void SetDtlsTransport(RTCDtlsTransport* aDtlsTransport, bool aStable);
   void RollbackToStableDtlsTransport();
 
   std::string GetTransportId() const {
-    return mJsepTransceiver->mTransport.mTransportId;
+    return mJsepTransceiver.mTransport.mTransportId;
   }
 
-  RefPtr<JsepTransceiver> GetJsepTransceiver() const {
+  JsepTransceiver& GetJsepTransceiver() { return mJsepTransceiver; }
-    return mJsepTransceiver;
-  }
 
   bool IsVideo() const;
 
@@ -193,7 +189,8 @@ class RTCRtpTransceiver : public nsISupports, public nsWrapperCache {
   RefPtr<PeerConnectionImpl> mPc;
   RefPtr<MediaTransportHandler> mTransportHandler;
   const std::string mTransceiverId;
-  RefPtr<JsepTransceiver> mJsepTransceiver;
+  // Copy of latest from the JSEP engine.
+  JsepTransceiver mJsepTransceiver;
   nsCOMPtr<nsISerialEventTarget> mStsThread;
   // state for webrtc.org that is shared between all transceivers
   RefPtr<WebrtcCallWrapper> mCallWrapper;

dom/media/webrtc/jsep/JsepSession.h

@@ -113,8 +113,8 @@ class JsepSession {
   void ForEachCodec(UnaryFunction& function) {
     std::for_each(Codecs().begin(), Codecs().end(), function);
     for (auto& transceiver : GetTransceivers()) {
-      transceiver->mSendTrack.ForEachCodec(function);
+      transceiver.mSendTrack.ForEachCodec(function);
-      transceiver->mRecvTrack.ForEachCodec(function);
+      transceiver.mRecvTrack.ForEachCodec(function);
     }
   }
 
@@ -122,24 +122,63 @@ class JsepSession {
   void SortCodecs(BinaryPredicate& sorter) {
     std::stable_sort(Codecs().begin(), Codecs().end(), sorter);
     for (auto& transceiver : GetTransceivers()) {
-      transceiver->mSendTrack.SortCodecs(sorter);
+      transceiver.mSendTrack.SortCodecs(sorter);
-      transceiver->mRecvTrack.SortCodecs(sorter);
+      transceiver.mRecvTrack.SortCodecs(sorter);
     }
   }
 
-  // Returns transceivers in the order they were added.
+  // Would be nice to have this return a Maybe containing the return of
-  virtual const std::vector<RefPtr<JsepTransceiver>>& GetTransceivers()
+  // |aFunction|, but Maybe cannot contain a void.
-      const = 0;
+  template <typename UnaryFunction>
-  virtual std::vector<RefPtr<JsepTransceiver>>& GetTransceivers() = 0;
+  bool ApplyToTransceiver(const std::string& aId, UnaryFunction&& aFunction) {
-  RefPtr<JsepTransceiver> GetTransceiver(const std::string& aId) const {
+    for (auto& transceiver : GetTransceivers()) {
+      if (transceiver.GetUuid() == aId) {
+        std::forward<UnaryFunction>(aFunction)(transceiver);
+        return true;
+      }
+    }
+    return false;
+  }
+
+  template <typename UnaryFunction>
+  void ForEachTransceiver(UnaryFunction&& aFunction) {
+    for (auto& transceiver : GetTransceivers()) {
+      std::forward<UnaryFunction>(aFunction)(transceiver);
+    }
+  }
+
+  template <typename UnaryFunction>
+  void ForEachTransceiver(UnaryFunction&& aFunction) const {
     for (const auto& transceiver : GetTransceivers()) {
-      if (transceiver->GetUuid() == aId) {
+      std::forward<UnaryFunction>(aFunction)(transceiver);
-        return transceiver;
     }
   }
-    return nullptr;
+
+  Maybe<const JsepTransceiver> GetTransceiver(const std::string& aId) const {
+    for (const auto& transceiver : GetTransceivers()) {
+      if (transceiver.GetUuid() == aId) {
+        return Some(transceiver);
       }
-  virtual void AddTransceiver(RefPtr<JsepTransceiver> transceiver) = 0;
+    }
+    return Nothing();
+  }
+
+  template <typename MatchFunction>
+  Maybe<const JsepTransceiver> FindTransceiver(MatchFunction&& aFunc) const {
+    for (const auto& transceiver : GetTransceivers()) {
+      if (std::forward<MatchFunction>(aFunc)(transceiver)) {
+        return Some(transceiver);
+      }
+    }
+    return Nothing();
+  }
+
+  bool SetTransceiver(const JsepTransceiver& aNew) {
+    return ApplyToTransceiver(aNew.GetUuid(),
+                              [aNew](JsepTransceiver& aOld) { aOld = aNew; });
+  }
+
+  virtual void AddTransceiver(const JsepTransceiver& transceiver) = 0;
 
   class Result {
    public:
@@ -211,14 +250,14 @@ class JsepSession {
     memset(sending, 0, sizeof(sending));
 
     for (const auto& transceiver : GetTransceivers()) {
-      if (transceiver->mRecvTrack.GetActive() ||
+      if (transceiver.mRecvTrack.GetActive() ||
-          transceiver->GetMediaType() == SdpMediaSection::kApplication) {
+          transceiver.GetMediaType() == SdpMediaSection::kApplication) {
-        receiving[transceiver->mRecvTrack.GetMediaType()]++;
+        receiving[transceiver.mRecvTrack.GetMediaType()]++;
       }
 
-      if (transceiver->mSendTrack.GetActive() ||
+      if (transceiver.mSendTrack.GetActive() ||
-          transceiver->GetMediaType() == SdpMediaSection::kApplication) {
+          transceiver.GetMediaType() == SdpMediaSection::kApplication) {
-        sending[transceiver->mSendTrack.GetMediaType()]++;
+        sending[transceiver.mSendTrack.GetMediaType()]++;
       }
     }
   }
@@ -230,6 +269,11 @@ class JsepSession {
   void SetRtxIsAllowed(bool aRtxIsAllowed) { mRtxIsAllowed = aRtxIsAllowed; }
 
  protected:
+  friend class JsepSessionTest;
+  // Returns transceivers in the order they were added.
+  virtual std::vector<JsepTransceiver>& GetTransceivers() = 0;
+  virtual const std::vector<JsepTransceiver>& GetTransceivers() const = 0;
+
   const std::string mName;
   JsepSignalingState mState;
   uint32_t mNegotiations;

dom/media/webrtc/jsep/JsepSessionImpl.cpp

@@ -91,14 +91,6 @@ JsepSessionImpl::JsepSessionImpl(const JsepSessionImpl& aOrig)
                                     : nullptr),
       mSdpHelper(&mLastError),
       mParser(new HybridSdpParser()) {
-  for (const auto& transceiver : aOrig.mTransceivers) {
-    // Deep copy
-    mTransceivers.push_back(new JsepTransceiver(*transceiver));
-  }
-  for (const auto& transceiver : aOrig.mOldTransceivers) {
-    // Deep copy
-    mOldTransceivers.push_back(new JsepTransceiver(*transceiver));
-  }
   for (const auto& codec : aOrig.mSupportedCodecs) {
     mSupportedCodecs.emplace_back(codec->Clone());
   }
@@ -145,20 +137,20 @@ JsepSessionImpl::GetLocalIceCredentials() const {
   return result;
 }
 
-void JsepSessionImpl::AddTransceiver(RefPtr<JsepTransceiver> aTransceiver) {
+void JsepSessionImpl::AddTransceiver(const JsepTransceiver& aTransceiver) {
   mLastError.clear();
-  MOZ_MTLOG(ML_DEBUG, "[" << mName << "]: Adding transceiver "
+  MOZ_MTLOG(ML_DEBUG,
-                          << aTransceiver->GetUuid());
+            "[" << mName << "]: Adding transceiver " << aTransceiver.GetUuid());
-  InitTransceiver(*aTransceiver);
 #ifdef DEBUG
-  if (aTransceiver->GetMediaType() == SdpMediaSection::kApplication) {
+  if (aTransceiver.GetMediaType() == SdpMediaSection::kApplication) {
     // Make sure we don't add more than one DataChannel transceiver
     for (const auto& transceiver : mTransceivers) {
-      MOZ_ASSERT(transceiver->GetMediaType() != SdpMediaSection::kApplication);
+      MOZ_ASSERT(transceiver.GetMediaType() != SdpMediaSection::kApplication);
     }
   }
 #endif
   mTransceivers.push_back(aTransceiver);
+  InitTransceiver(mTransceivers.back());
 }
 
 void JsepSessionImpl::InitTransceiver(JsepTransceiver& aTransceiver) {
@@ -409,9 +401,11 @@ JsepSession::Result JsepSessionImpl::CreateOffer(
   NS_ENSURE_SUCCESS(rv, dom::PCError::OperationError);
 
   for (size_t level = 0;
-       JsepTransceiver* transceiver = GetTransceiverForLocal(level); ++level) {
+       Maybe<JsepTransceiver> transceiver = GetTransceiverForLocal(level);
+       ++level) {
     rv = CreateOfferMsection(options, *transceiver, sdp.get());
     NS_ENSURE_SUCCESS(rv, dom::PCError::OperationError);
+    SetTransceiver(*transceiver);
   }
 
   SetupBundle(sdp.get());
@@ -568,7 +562,7 @@ JsepSession::Result JsepSessionImpl::CreateAnswer(
 
   for (size_t i = 0; i < offer.GetMediaSectionCount(); ++i) {
     // The transceivers are already in place, due to setRemote
-    JsepTransceiver* transceiver(GetTransceiverForLevel(i));
+    Maybe<JsepTransceiver> transceiver(GetTransceiverForLevel(i));
     if (!transceiver) {
       JSEP_SET_ERROR("No transceiver for level " << i);
       MOZ_ASSERT(false);
@@ -577,6 +571,7 @@ JsepSession::Result JsepSessionImpl::CreateAnswer(
     rv = CreateAnswerMsection(options, *transceiver, offer.GetMediaSection(i),
                               sdp.get());
     NS_ENSURE_SUCCESS(rv, dom::PCError::OperationError);
+    SetTransceiver(*transceiver);
   }
 
   // Ensure that each bundle-group starts with a mid that has a transport, in
@@ -814,10 +809,7 @@ JsepSession::Result JsepSessionImpl::SetLocalDescription(
 
   if (type == kJsepSdpOffer) {
     // Save in case we need to rollback
-    mOldTransceivers.clear();
+    mOldTransceivers = mTransceivers;
-    for (const auto& transceiver : mTransceivers) {
-      mOldTransceivers.push_back(new JsepTransceiver(*transceiver));
-    }
   }
 
   SdpHelper::BundledMids bundledMids;
@@ -832,7 +824,7 @@ JsepSession::Result JsepSessionImpl::SetLocalDescription(
   }
 
   for (size_t i = 0; i < parsed->GetMediaSectionCount(); ++i) {
-    JsepTransceiver* transceiver(GetTransceiverForLevel(i));
+    Maybe<JsepTransceiver> transceiver(GetTransceiverForLevel(i));
     if (!transceiver) {
       MOZ_ASSERT(false);
       JSEP_SET_ERROR("No transceiver for level " << i);
@@ -845,6 +837,7 @@ JsepSession::Result JsepSessionImpl::SetLocalDescription(
 
     if (mSdpHelper.MsectionIsDisabled(msection)) {
       transceiver->mTransport.Close();
+      SetTransceiver(*transceiver);
       continue;
     }
 
@@ -860,7 +853,7 @@ JsepSession::Result JsepSessionImpl::SetLocalDescription(
     }
 
     if (hasOwnTransport) {
-      EnsureHasOwnTransport(parsed->GetMediaSection(i), transceiver);
+      EnsureHasOwnTransport(parsed->GetMediaSection(i), *transceiver);
     }
 
     if (type == kJsepSdpOffer) {
@@ -876,6 +869,7 @@ JsepSession::Result JsepSessionImpl::SetLocalDescription(
         transceiver->SetBundleLevel(it->second->GetLevel());
       }
     }
+    SetTransceiver(*transceiver);
   }
 
   CopyBundleTransports();
@@ -1024,15 +1018,14 @@ JsepSession::Result JsepSessionImpl::SetRemoteDescription(
     iceOptions = parsed->GetAttributeList().GetIceOptions().mValues;
   }
 
-  // Save in case we need to rollback.
   if (type == kJsepSdpOffer) {
-    mOldTransceivers.clear();
+    // Save in case we need to rollback.
-    for (const auto& transceiver : mTransceivers) {
+    mOldTransceivers = mTransceivers;
-      mOldTransceivers.push_back(new JsepTransceiver(*transceiver));
+    for (auto& transceiver : mTransceivers) {
-      if (!transceiver->IsNegotiated()) {
+      if (!transceiver.IsNegotiated()) {
         // We chose a level for this transceiver, but never negotiated it.
         // Discard this state.
-        transceiver->ClearLevel();
+        transceiver.ClearLevel();
       }
     }
   }
@@ -1085,18 +1078,19 @@ nsresult JsepSessionImpl::HandleNegotiatedSession(
 
   // First, set the bundle level on the transceivers
   for (auto& [mid, transportOwner] : bundledMids) {
-    JsepTransceiver* bundledTransceiver = GetTransceiverForMid(mid);
+    Maybe<JsepTransceiver> bundledTransceiver = GetTransceiverForMid(mid);
     if (!bundledTransceiver) {
       JSEP_SET_ERROR("No transceiver for bundled mid " << mid);
       return NS_ERROR_INVALID_ARG;
     }
     bundledTransceiver->SetBundleLevel(transportOwner->GetLevel());
+    SetTransceiver(*bundledTransceiver);
   }
 
   // Now walk through the m-sections, perform negotiation, and update the
   // transceivers.
   for (size_t i = 0; i < local->GetMediaSectionCount(); ++i) {
-    JsepTransceiver* transceiver(GetTransceiverForLevel(i));
+    Maybe<JsepTransceiver> transceiver(GetTransceiverForLevel(i));
     if (!transceiver) {
       MOZ_ASSERT(false);
       JSEP_SET_ERROR("No transceiver for level " << i);
@@ -1112,20 +1106,22 @@ nsresult JsepSessionImpl::HandleNegotiatedSession(
       transceiver->mSendTrack.SetActive(false);
       transceiver->mRecvTrack.SetActive(false);
       transceiver->SetCanRecycle();
+      SetTransceiver(*transceiver);
       // Do not clear mLevel yet! That will happen on the next negotiation.
       continue;
     }
 
     rv = MakeNegotiatedTransceiver(remote->GetMediaSection(i),
-                                   local->GetMediaSection(i), transceiver);
+                                   local->GetMediaSection(i), *transceiver);
     NS_ENSURE_SUCCESS(rv, rv);
+    SetTransceiver(*transceiver);
   }
 
   CopyBundleTransports();
 
   std::vector<JsepTrack*> remoteTracks;
-  for (const auto& transceiver : mTransceivers) {
+  for (auto& transceiver : mTransceivers) {
-    remoteTracks.push_back(&transceiver->mRecvTrack);
+    remoteTracks.push_back(&transceiver.mRecvTrack);
   }
   JsepTrack::SetUniquePayloadTypes(remoteTracks);
 
@@ -1139,14 +1135,14 @@ nsresult JsepSessionImpl::HandleNegotiatedSession(
 
 nsresult JsepSessionImpl::MakeNegotiatedTransceiver(
     const SdpMediaSection& remote, const SdpMediaSection& local,
-    JsepTransceiver* transceiver) {
+    JsepTransceiver& transceiver) {
   const SdpMediaSection& answer = *mIsPendingOfferer ? remote : local;
 
   bool sending = false;
   bool receiving = false;
 
   // JS could stop the transceiver after the answer was created.
-  if (!transceiver->IsStopped()) {
+  if (!transceiver.IsStopped()) {
     if (*mIsPendingOfferer) {
       receiving = answer.IsSending();
       sending = answer.IsReceiving();
@@ -1161,23 +1157,23 @@ nsresult JsepSessionImpl::MakeNegotiatedTransceiver(
                           << local.GetMediaType() << " sending=" << sending
                           << " receiving=" << receiving);
 
-  transceiver->SetNegotiated();
+  transceiver.SetNegotiated();
 
   // Ensure that this is finalized in case we need to copy it below
   nsresult rv =
       FinalizeTransport(remote.GetAttributeList(), answer.GetAttributeList(),
-                        &transceiver->mTransport);
+                        &transceiver.mTransport);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  transceiver->mSendTrack.SetActive(sending);
+  transceiver.mSendTrack.SetActive(sending);
-  rv = transceiver->mSendTrack.Negotiate(answer, remote, local);
+  rv = transceiver.mSendTrack.Negotiate(answer, remote, local);
   if (NS_FAILED(rv)) {
     JSEP_SET_ERROR("Answer had no codecs in common with offer in m-section "
                    << local.GetLevel());
     return rv;
   }
 
-  JsepTrack& recvTrack = transceiver->mRecvTrack;
+  JsepTrack& recvTrack = transceiver.mRecvTrack;
   recvTrack.SetActive(receiving);
   rv = recvTrack.Negotiate(answer, remote, local);
   if (NS_FAILED(rv)) {
@@ -1186,7 +1182,7 @@ nsresult JsepSessionImpl::MakeNegotiatedTransceiver(
     return rv;
   }
 
-  if (transceiver->HasBundleLevel() && recvTrack.GetSsrcs().empty() &&
+  if (transceiver.HasBundleLevel() && recvTrack.GetSsrcs().empty() &&
       recvTrack.GetMediaType() != SdpMediaSection::kApplication) {
     // TODO(bug 1105005): Once we have urn:ietf:params:rtp-hdrext:sdes:mid
     // support, we should only fire this warning if that extension was not
@@ -1197,7 +1193,7 @@ nsresult JsepSessionImpl::MakeNegotiatedTransceiver(
                                "dropped.");
   }
 
-  if (transceiver->mTransport.mComponents == 2) {
+  if (transceiver.mTransport.mComponents == 2) {
     // RTCP MUX or not.
     // TODO(bug 1095743): verify that the PTs are consistent with mux.
     MOZ_MTLOG(ML_DEBUG, "[" << mName << "]: RTCP-MUX is off");
@@ -1234,10 +1230,10 @@ nsresult JsepSessionImpl::MakeNegotiatedTransceiver(
 }
 
 void JsepSessionImpl::EnsureHasOwnTransport(const SdpMediaSection& msection,
-                                            JsepTransceiver* transceiver) {
+                                            JsepTransceiver& transceiver) {
-  JsepTransport& transport = transceiver->mTransport;
+  JsepTransport& transport = transceiver.mTransport;
 
-  if (!transceiver->HasOwnTransport()) {
+  if (!transceiver.HasOwnTransport()) {
     // Transceiver didn't own this transport last time, it won't now either
     transport.Close();
   }
@@ -1245,7 +1241,7 @@ void JsepSessionImpl::EnsureHasOwnTransport(const SdpMediaSection& msection,
   transport.mLocalUfrag = msection.GetAttributeList().GetIceUfrag();
   transport.mLocalPwd = msection.GetAttributeList().GetIcePwd();
 
-  transceiver->ClearBundleLevel();
+  transceiver.ClearBundleLevel();
 
   if (!transport.mComponents) {
     if (mSdpHelper.HasRtcp(msection.GetProtocol())) {
@@ -1266,34 +1262,34 @@ void JsepSessionImpl::EnsureHasOwnTransport(const SdpMediaSection& msection,
 
 void JsepSessionImpl::CopyBundleTransports() {
   for (auto& transceiver : mTransceivers) {
-    if (transceiver->HasBundleLevel()) {
+    if (transceiver.HasBundleLevel()) {
       MOZ_MTLOG(ML_DEBUG,
-                "[" << mName << "] Transceiver " << transceiver->GetLevel()
+                "[" << mName << "] Transceiver " << transceiver.GetLevel()
                     << " is in a bundle; transceiver "
-                    << transceiver->BundleLevel() << " owns the transport.");
+                    << transceiver.BundleLevel() << " owns the transport.");
-      const JsepTransceiver* transportOwner =
+      Maybe<const JsepTransceiver> transportOwner =
-          GetTransceiverForLevel(transceiver->BundleLevel());
+          GetTransceiverForLevel(transceiver.BundleLevel());
       MOZ_ASSERT(transportOwner);
       if (transportOwner) {
-        transceiver->mTransport = transportOwner->mTransport;
+        transceiver.mTransport = transportOwner->mTransport;
       }
-    } else if (transceiver->HasLevel()) {
+    } else if (transceiver.HasLevel()) {
       MOZ_MTLOG(ML_DEBUG, "[" << mName << "] Transceiver "
-                              << transceiver->GetLevel()
+                              << transceiver.GetLevel()
                               << " is not necessarily in a bundle.");
     }
-    if (transceiver->HasLevel()) {
+    if (transceiver.HasLevel()) {
       MOZ_MTLOG(ML_DEBUG,
-                "[" << mName << "] Transceiver " << transceiver->GetLevel()
+                "[" << mName << "] Transceiver " << transceiver.GetLevel()
-                    << " transport-id: " << transceiver->mTransport.mTransportId
+                    << " transport-id: " << transceiver.mTransport.mTransportId
-                    << " components: " << transceiver->mTransport.mComponents);
+                    << " components: " << transceiver.mTransport.mComponents);
     }
   }
 }
 
 nsresult JsepSessionImpl::FinalizeTransport(const SdpAttributeList& remote,
                                             const SdpAttributeList& answer,
-                                            JsepTransport* transport) {
+                                            JsepTransport* transport) const {
   if (!transport->mComponents) {
     return NS_OK;
   }
@@ -1382,7 +1378,7 @@ nsresult JsepSessionImpl::CopyPreviousTransportParams(
       // If newLocal is an offer, this will be the number of components we used
       // last time, and if it is an answer, this will be the number of
       // components we've decided we're using now.
-      JsepTransceiver* transceiver(GetTransceiverForLevel(i));
+      Maybe<const JsepTransceiver> transceiver(GetTransceiverForLevel(i));
       if (!transceiver) {
         MOZ_ASSERT(false);
         JSEP_SET_ERROR("No transceiver for level " << i);
@@ -1545,43 +1541,39 @@ nsresult JsepSessionImpl::SetRemoteDescriptionAnswer(JsepSdpType type,
   return NS_OK;
 }
 
-JsepTransceiver* JsepSessionImpl::GetTransceiverForLevel(size_t level) const {
+Maybe<JsepTransceiver> JsepSessionImpl::GetTransceiverForLevel(
-  for (const auto& transceiver : mTransceivers) {
+    size_t level) const {
-    if (transceiver->HasLevel() && (transceiver->GetLevel() == level)) {
+  return FindTransceiver([level](const JsepTransceiver& transceiver) {
-      return transceiver.get();
+    return transceiver.HasLevel() && (transceiver.GetLevel() == level);
-    }
+  });
 }
 
-  return nullptr;
+Maybe<JsepTransceiver> JsepSessionImpl::GetTransceiverForMid(
-}
-
-JsepTransceiver* JsepSessionImpl::GetTransceiverForMid(
     const std::string& mid) const {
-  for (const auto& transceiver : mTransceivers) {
+  return FindTransceiver([mid](const JsepTransceiver& transceiver) {
-    if (transceiver->IsAssociated() && (transceiver->GetMid() == mid)) {
+    return transceiver.IsAssociated() && (transceiver.GetMid() == mid);
-      return transceiver.get();
+  });
-    }
 }
 
-  return nullptr;
+Maybe<JsepTransceiver> JsepSessionImpl::GetTransceiverForLocal(size_t level) {
-}
+  if (Maybe<JsepTransceiver> transceiver = GetTransceiverForLevel(level)) {
-
-JsepTransceiver* JsepSessionImpl::GetTransceiverForLocal(size_t level) {
-  if (JsepTransceiver* transceiver = GetTransceiverForLevel(level)) {
     if (transceiver->CanRecycle() &&
         transceiver->GetMediaType() != SdpMediaSection::kApplication) {
       // Attempt to recycle. If this fails, the old transceiver stays put.
       transceiver->Disassociate();
-      JsepTransceiver* newTransceiver =
+      Maybe<JsepTransceiver> newTransceiver =
           FindUnassociatedTransceiver(transceiver->GetMediaType(), false);
       if (newTransceiver) {
         newTransceiver->SetLevel(level);
         transceiver->ClearLevel();
         transceiver->mSendTrack.ClearRids();
+        SetTransceiver(*newTransceiver);
+        SetTransceiver(*transceiver);
         return newTransceiver;
       }
     }
 
+    SetTransceiver(*transceiver);
     return transceiver;
   }
 
@@ -1589,66 +1581,67 @@ JsepTransceiver* JsepSessionImpl::GetTransceiverForLocal(size_t level) {
 
   // Look for an RTP transceiver
   for (auto& transceiver : mTransceivers) {
-    if (transceiver->GetMediaType() != SdpMediaSection::kApplication &&
+    if (transceiver.GetMediaType() != SdpMediaSection::kApplication &&
-        !transceiver->IsStopped() && !transceiver->HasLevel()) {
+        !transceiver.IsStopped() && !transceiver.HasLevel()) {
-      transceiver->SetLevel(level);
+      transceiver.SetLevel(level);
-      return transceiver.get();
+      return Some(transceiver);
     }
   }
 
   // Ok, look for a datachannel
   for (auto& transceiver : mTransceivers) {
-    if (!transceiver->IsStopped() && !transceiver->HasLevel()) {
+    if (!transceiver.IsStopped() && !transceiver.HasLevel()) {
-      transceiver->SetLevel(level);
+      transceiver.SetLevel(level);
-      return transceiver.get();
+      return Some(transceiver);
     }
   }
 
-  return nullptr;
+  return Nothing();
 }
 
-JsepTransceiver* JsepSessionImpl::GetTransceiverForRemote(
+Maybe<JsepTransceiver> JsepSessionImpl::GetTransceiverForRemote(
     const SdpMediaSection& msection) {
   size_t level = msection.GetLevel();
-  if (JsepTransceiver* transceiver = GetTransceiverForLevel(level)) {
+  Maybe<JsepTransceiver> transceiver = GetTransceiverForLevel(level);
+  if (transceiver) {
     if (!transceiver->CanRecycle()) {
       return transceiver;
     }
     transceiver->Disassociate();
     transceiver->ClearLevel();
     transceiver->mSendTrack.ClearRids();
+    SetTransceiver(*transceiver);
   }
 
   // No transceiver for |level|
-
+  transceiver = FindUnassociatedTransceiver(msection.GetMediaType(), true);
-  JsepTransceiver* transceiver =
-      FindUnassociatedTransceiver(msection.GetMediaType(), true /*magic!*/);
   if (transceiver) {
     transceiver->SetLevel(level);
+    SetTransceiver(*transceiver);
     return transceiver;
   }
 
   // Make a new transceiver
-  RefPtr<JsepTransceiver> newTransceiver(new JsepTransceiver(
+  JsepTransceiver newTransceiver(msection.GetMediaType(), *mUuidGen,
-      msection.GetMediaType(), *mUuidGen, SdpDirectionAttribute::kRecvonly));
+                                 SdpDirectionAttribute::kRecvonly);
-  newTransceiver->SetLevel(level);
+  newTransceiver.SetLevel(level);
-  newTransceiver->SetOnlyExistsBecauseOfSetRemote(true);
+  newTransceiver.SetOnlyExistsBecauseOfSetRemote(true);
   AddTransceiver(newTransceiver);
-  return newTransceiver.get();
+  return Some(mTransceivers.back());
 }
 
-JsepTransceiver* JsepSessionImpl::GetTransceiverWithTransport(
+Maybe<JsepTransceiver> JsepSessionImpl::GetTransceiverWithTransport(
     const std::string& transportId) const {
   for (const auto& transceiver : mTransceivers) {
-    if (transceiver->HasOwnTransport() &&
+    if (transceiver.HasOwnTransport() &&
-        (transceiver->mTransport.mTransportId == transportId)) {
+        (transceiver.mTransport.mTransportId == transportId)) {
-      MOZ_ASSERT(transceiver->HasLevel(),
+      MOZ_ASSERT(transceiver.HasLevel(),
                  "Transceiver has a transport, but no level!");
-      return transceiver.get();
+      return Some(transceiver);
     }
   }
 
-  return nullptr;
+  return Nothing();
 }
 
 nsresult JsepSessionImpl::UpdateTransceiversFromRemoteDescription(
@@ -1657,7 +1650,7 @@ nsresult JsepSessionImpl::UpdateTransceiversFromRemoteDescription(
   for (size_t i = 0; i < remote.GetMediaSectionCount(); ++i) {
     const SdpMediaSection& msection = remote.GetMediaSection(i);
 
-    JsepTransceiver* transceiver(GetTransceiverForRemote(msection));
+    Maybe<JsepTransceiver> transceiver(GetTransceiverForRemote(msection));
     if (!transceiver) {
       return NS_ERROR_FAILURE;
     }
@@ -1677,10 +1670,12 @@ nsresult JsepSessionImpl::UpdateTransceiversFromRemoteDescription(
       transceiver->Disassociate();
       // This cannot be rolled back.
       transceiver->Stop();
+      SetTransceiver(*transceiver);
       continue;
     }
 
     if (msection.GetMediaType() == SdpMediaSection::MediaType::kApplication) {
+      SetTransceiver(*transceiver);
       continue;
     }
 
@@ -1696,43 +1691,43 @@ nsresult JsepSessionImpl::UpdateTransceiversFromRemoteDescription(
     // msection is not sending. If the msection is sending, and there are no
     // a=msid, the previously set default will stay.
     transceiver->mRecvTrack.RecvTrackSetRemote(remote, msection);
+    SetTransceiver(*transceiver);
   }
 
   return NS_OK;
 }
 
-JsepTransceiver* JsepSessionImpl::FindUnassociatedTransceiver(
+Maybe<JsepTransceiver> JsepSessionImpl::FindUnassociatedTransceiver(
     SdpMediaSection::MediaType type, bool magic) {
   // Look through transceivers that are not mapped to an m-section
   for (auto& transceiver : mTransceivers) {
     if (type == SdpMediaSection::kApplication &&
-        type == transceiver->GetMediaType()) {
+        type == transceiver.GetMediaType()) {
-      transceiver->RestartDatachannelTransceiver();
+      transceiver.RestartDatachannelTransceiver();
-      return transceiver.get();
+      return Some(transceiver);
     }
-    if (!transceiver->IsStopped() && !transceiver->HasLevel() &&
+    if (!transceiver.IsStopped() && !transceiver.HasLevel() &&
-        (!magic || transceiver->HasAddTrackMagic()) &&
+        (!magic || transceiver.HasAddTrackMagic()) &&
-        (transceiver->GetMediaType() == type)) {
+        (transceiver.GetMediaType() == type)) {
-      return transceiver.get();
+      return Some(transceiver);
     }
   }
 
-  return nullptr;
+  return Nothing();
 }
 
 void JsepSessionImpl::RollbackLocalOffer() {
   for (size_t i = 0; i < mTransceivers.size(); ++i) {
-    auto transceiver = mTransceivers[i];
+    auto& transceiver = mTransceivers[i];
     if (mOldTransceivers.size() > i) {
-      transceiver->Rollback(*mOldTransceivers[i], false);
+      transceiver.Rollback(mOldTransceivers[i], false);
       mOldTransceivers[i] = transceiver;
       continue;
     }
 
-    RefPtr<JsepTransceiver> temp(
+    JsepTransceiver temp(transceiver.GetMediaType(), *mUuidGen);
-        new JsepTransceiver(transceiver->GetMediaType(), *mUuidGen));
+    InitTransceiver(temp);
-    InitTransceiver(*temp);
+    transceiver.Rollback(temp, false);
-    transceiver->Rollback(*temp, false);
     mOldTransceivers.push_back(transceiver);
   }
 
@@ -1741,10 +1736,10 @@ void JsepSessionImpl::RollbackLocalOffer() {
 
 void JsepSessionImpl::RollbackRemoteOffer() {
   for (size_t i = 0; i < mTransceivers.size(); ++i) {
-    auto transceiver = mTransceivers[i];
+    auto& transceiver = mTransceivers[i];
     if (mOldTransceivers.size() > i) {
       // Some stuff cannot be rolled back. Save this information.
-      transceiver->Rollback(*mOldTransceivers[i], true);
+      transceiver.Rollback(mOldTransceivers[i], true);
       mOldTransceivers[i] = transceiver;
       continue;
     }
@@ -1752,14 +1747,13 @@ void JsepSessionImpl::RollbackRemoteOffer() {
     // New transceiver!
     // We rollback even for transceivers we will remove, just to ensure we end
     // up at the starting state.
-    RefPtr<JsepTransceiver> temp(
+    JsepTransceiver temp(transceiver.GetMediaType(), *mUuidGen);
-        new JsepTransceiver(transceiver->GetMediaType(), *mUuidGen));
+    InitTransceiver(temp);
-    InitTransceiver(*temp);
+    transceiver.Rollback(temp, true);
-    transceiver->Rollback(*temp, true);
 
-    if (transceiver->OnlyExistsBecauseOfSetRemote()) {
+    if (transceiver.OnlyExistsBecauseOfSetRemote()) {
-      transceiver->Stop();
+      transceiver.Stop();
-      transceiver->SetRemoved();
+      transceiver.SetRemoved();
     }
     mOldTransceivers.push_back(transceiver);
   }
@@ -2197,7 +2191,7 @@ JsepSession::Result JsepSessionImpl::AddRemoteIceCandidate(
     return Result();
   }
 
-  JsepTransceiver* transceiver = nullptr;
+  Maybe<JsepTransceiver> transceiver;
   if (!mid.empty()) {
     transceiver = GetTransceiverForMid(mid);
   } else if (level.isSome()) {
@@ -2249,7 +2243,8 @@ nsresult JsepSessionImpl::AddLocalIceCandidate(const std::string& candidate,
     return NS_ERROR_UNEXPECTED;
   }
 
-  JsepTransceiver* transceiver = GetTransceiverWithTransport(transportId);
+  Maybe<const JsepTransceiver> transceiver =
+      GetTransceiverWithTransport(transportId);
   if (!transceiver || !transceiver->IsAssociated()) {
     // mainly here to make some testing less complicated, but also just in case
     return NS_OK;
@@ -2292,20 +2287,20 @@ nsresult JsepSessionImpl::UpdateDefaultCandidate(
   for (const auto& transceiver : mTransceivers) {
     // We set the default address for bundled m-sections, but not candidate
     // attributes. Ugh.
-    if (transceiver->mTransport.mTransportId == transportId) {
+    if (transceiver.mTransport.mTransportId == transportId) {
-      MOZ_ASSERT(transceiver->HasLevel(),
+      MOZ_ASSERT(transceiver.HasLevel(),
                  "Transceiver has a transport, but no level! "
                  "This should never happen.");
       std::string defaultRtcpCandidateAddrCopy(defaultRtcpCandidateAddr);
       if (mState == kJsepStateStable) {
-        if (transceiver->mTransport.mComponents == 1) {
+        if (transceiver.mTransport.mComponents == 1) {
           // We know we're doing rtcp-mux by now. Don't create an rtcp attr.
           defaultRtcpCandidateAddrCopy = "";
           defaultRtcpCandidatePort = 0;
         }
       }
 
-      size_t level = transceiver->GetLevel();
+      size_t level = transceiver.GetLevel();
       if (level >= sdp->GetMediaSectionCount()) {
         MOZ_ASSERT(false, "Transceiver's level is too large!");
         JSEP_SET_ERROR("Transceiver's level is too large!");
@@ -2404,8 +2399,8 @@ bool JsepSessionImpl::CheckNegotiationNeeded() const {
   MOZ_ASSERT(mState == kJsepStateStable);
 
   for (const auto& transceiver : mTransceivers) {
-    if (transceiver->IsStopped()) {
+    if (transceiver.IsStopped()) {
-      if (transceiver->IsAssociated()) {
+      if (transceiver.IsAssociated()) {
         MOZ_MTLOG(ML_DEBUG, "[" << mName
                                 << "]: Negotiation needed because of "
                                    "stopped transceiver that still has a mid.");
@@ -2414,7 +2409,7 @@ bool JsepSessionImpl::CheckNegotiationNeeded() const {
       continue;
     }
 
-    if (!transceiver->IsAssociated()) {
+    if (!transceiver.IsAssociated()) {
       MOZ_MTLOG(ML_DEBUG, "[" << mName
                               << "]: Negotiation needed because of "
                                  "unassociated (but not stopped) transceiver.");
@@ -2428,16 +2423,16 @@ bool JsepSessionImpl::CheckNegotiationNeeded() const {
       continue;
     }
 
-    if (!transceiver->HasLevel()) {
+    if (!transceiver.HasLevel()) {
       MOZ_CRASH("Associated transceivers should always have a level.");
       continue;
     }
 
-    if (transceiver->GetMediaType() == SdpMediaSection::kApplication) {
+    if (transceiver.GetMediaType() == SdpMediaSection::kApplication) {
       continue;
     }
 
-    size_t level = transceiver->GetLevel();
+    size_t level = transceiver.GetLevel();
     if (NS_WARN_IF(mCurrentLocalDescription->GetMediaSectionCount() <= level) ||
         NS_WARN_IF(mCurrentRemoteDescription->GetMediaSectionCount() <=
                    level)) {
@@ -2450,7 +2445,7 @@ bool JsepSessionImpl::CheckNegotiationNeeded() const {
     const SdpMediaSection& remote =
         mCurrentRemoteDescription->GetMediaSection(level);
 
-    if (transceiver->mJsDirection & sdp::kSend) {
+    if (transceiver.mJsDirection & sdp::kSend) {
       std::vector<std::string> sdpMsids;
       if (local.GetAttributeList().HasAttribute(SdpAttribute::kMsidAttribute)) {
         for (const auto& msidAttr : local.GetAttributeList().GetMsid().mMsids) {
@@ -2462,7 +2457,7 @@ bool JsepSessionImpl::CheckNegotiationNeeded() const {
       std::sort(sdpMsids.begin(), sdpMsids.end());
 
       std::vector<std::string> jsepMsids;
-      for (const auto& jsepMsid : transceiver->mSendTrack.GetStreamIds()) {
+      for (const auto& jsepMsid : transceiver.mSendTrack.GetStreamIds()) {
         jsepMsids.push_back(jsepMsid);
       }
       std::sort(jsepMsids.begin(), jsepMsids.end());
@@ -2489,8 +2484,8 @@ bool JsepSessionImpl::CheckNegotiationNeeded() const {
     }
 
     if (mIsCurrentOfferer.isSome() && *mIsCurrentOfferer) {
-      if ((local.GetDirection() != transceiver->mJsDirection) &&
+      if ((local.GetDirection() != transceiver.mJsDirection) &&
-          reverse(remote.GetDirection()) != transceiver->mJsDirection) {
+          reverse(remote.GetDirection()) != transceiver.mJsDirection) {
         MOZ_MTLOG(ML_DEBUG, "[" << mName
                                 << "]: Negotiation needed because "
                                    "the direction on our offer, and the remote "
@@ -2499,7 +2494,7 @@ bool JsepSessionImpl::CheckNegotiationNeeded() const {
         return true;
       }
     } else if (local.GetDirection() !=
-               (transceiver->mJsDirection & reverse(remote.GetDirection()))) {
+               (transceiver.mJsDirection & reverse(remote.GetDirection()))) {
       MOZ_MTLOG(
           ML_DEBUG,
           "[" << mName

dom/media/webrtc/jsep/JsepSessionImpl.h

@@ -57,6 +57,11 @@ class JsepSessionCopyableStuff {
   std::vector<std::pair<size_t, std::string>> mLastSdpParsingErrors;
   bool mEncodeTrackId = true;
   SsrcGenerator mSsrcGenerator;
+  // !!!NOT INDEXED BY LEVEL!!! The level mapping is done with
+  // JsepTransceiver::mLevel. The keys are UUIDs.
+  std::vector<JsepTransceiver> mTransceivers;
+  // So we can rollback. Not as simple as just going back to the old, though...
+  std::vector<JsepTransceiver> mOldTransceivers;
 };
 
 class JsepSessionImpl : public JsepSession, public JsepSessionCopyableStuff {
@@ -167,16 +172,7 @@ class JsepSessionImpl : public JsepSession, public JsepSessionCopyableStuff {
   virtual std::set<std::pair<std::string, std::string>> GetLocalIceCredentials()
       const override;
 
-  virtual const std::vector<RefPtr<JsepTransceiver>>& GetTransceivers()
+  virtual void AddTransceiver(const JsepTransceiver& transceiver) override;
-      const override {
-    return mTransceivers;
-  }
-
-  virtual std::vector<RefPtr<JsepTransceiver>>& GetTransceivers() override {
-    return mTransceivers;
-  }
-
-  virtual void AddTransceiver(RefPtr<JsepTransceiver> transceiver) override;
 
   virtual bool CheckNegotiationNeeded() const override;
 
@@ -185,6 +181,15 @@ class JsepSessionImpl : public JsepSession, public JsepSessionCopyableStuff {
       override;
 
  private:
+  friend class JsepSessionTest;
+  virtual const std::vector<JsepTransceiver>& GetTransceivers() const override {
+    return mTransceivers;
+  }
+
+  virtual std::vector<JsepTransceiver>& GetTransceivers() override {
+    return mTransceivers;
+  }
+
   // Non-const so it can set mLastError
   nsresult CreateGenericSDP(UniquePtr<Sdp>* sdp);
   void AddExtmap(SdpMediaSection* msection);
@@ -208,16 +213,17 @@ class JsepSessionImpl : public JsepSession, public JsepSessionCopyableStuff {
   nsresult ValidateOffer(const Sdp& offer);
   nsresult ValidateAnswer(const Sdp& offer, const Sdp& answer);
   nsresult UpdateTransceiversFromRemoteDescription(const Sdp& remote);
-  JsepTransceiver* GetTransceiverForLevel(size_t level) const;
+  Maybe<JsepTransceiver> GetTransceiverForLevel(size_t level) const;
-  JsepTransceiver* GetTransceiverForMid(const std::string& mid) const;
+  Maybe<JsepTransceiver> GetTransceiverForMid(const std::string& mid) const;
-  JsepTransceiver* GetTransceiverForLocal(size_t level);
+  Maybe<JsepTransceiver> GetTransceiverForLocal(size_t level);
-  JsepTransceiver* GetTransceiverForRemote(const SdpMediaSection& msection);
+  Maybe<JsepTransceiver> GetTransceiverForRemote(
-  JsepTransceiver* GetTransceiverWithTransport(
+      const SdpMediaSection& msection);
+  Maybe<JsepTransceiver> GetTransceiverWithTransport(
       const std::string& transportId) const;
   // The w3c and IETF specs have a lot of "magical" behavior that happens when
   // addTrack is used. This was a deliberate design choice. Sadface.
-  JsepTransceiver* FindUnassociatedTransceiver(SdpMediaSection::MediaType type,
+  Maybe<JsepTransceiver> FindUnassociatedTransceiver(
-                                               bool magic);
+      SdpMediaSection::MediaType type, bool magic);
   // Called for rollback of local description
   void RollbackLocalOffer();
   // Called for rollback of remote description
@@ -241,14 +247,14 @@ class JsepSessionImpl : public JsepSession, public JsepSessionCopyableStuff {
                                       SdpSetupAttribute::Role* rolep);
   nsresult MakeNegotiatedTransceiver(const SdpMediaSection& remote,
                                      const SdpMediaSection& local,
-                                     JsepTransceiver* transceiverOut);
+                                     JsepTransceiver& transceiverOut);
   void EnsureHasOwnTransport(const SdpMediaSection& msection,
-                             JsepTransceiver* transceiver);
+                             JsepTransceiver& transceiver);
   void CopyBundleTransports();
 
   nsresult FinalizeTransport(const SdpAttributeList& remote,
                              const SdpAttributeList& answer,
-                             JsepTransport* transport);
+                             JsepTransport* transport) const;
 
   nsresult GetNegotiatedBundledMids(SdpHelper::BundledMids* bundledMids);
 
@@ -263,12 +269,6 @@ class JsepSessionImpl : public JsepSession, public JsepSessionCopyableStuff {
 
   void InitTransceiver(JsepTransceiver& aTransceiver);
 
-  // !!!NOT INDEXED BY LEVEL!!! The level mapping is done with
-  // JsepTransceiver::mLevel. The keys are UUIDs.
-  std::vector<RefPtr<JsepTransceiver>> mTransceivers;
-  // So we can rollback. Not as simple as just going back to the old, though...
-  std::vector<RefPtr<JsepTransceiver>> mOldTransceivers;
-
   UniquePtr<JsepUuidGenerator> mUuidGen;
   UniquePtr<Sdp> mGeneratedOffer;   // Created but not set.
   UniquePtr<Sdp> mGeneratedAnswer;  // Created but not set.

dom/media/webrtc/jsep/JsepTransceiver.h

@@ -13,8 +13,6 @@
 #include "jsep/JsepTransport.h"
 #include "jsep/JsepTrack.h"
 
-#include <mozilla/OwningNonNull.h>
-#include "nsISupportsImpl.h"
 #include "nsError.h"
 
 namespace mozilla {
@@ -27,9 +25,6 @@ class JsepUuidGenerator {
 };
 
 class JsepTransceiver {
- private:
-  ~JsepTransceiver(){};
-
  public:
   explicit JsepTransceiver(SdpMediaSection::MediaType type,
                            JsepUuidGenerator& aUuidGen,
@@ -51,24 +46,12 @@ class JsepTransceiver {
     }
   }
 
-  // Can't use default copy c'tor because of the refcount members. Ugh.
+  JsepTransceiver(const JsepTransceiver& orig) = default;
-  JsepTransceiver(const JsepTransceiver& orig)
+  JsepTransceiver(JsepTransceiver&& orig) = default;
-      : mJsDirection(orig.mJsDirection),
+  JsepTransceiver& operator=(const JsepTransceiver& aRhs) = default;
-        mSendTrack(orig.mSendTrack),
+  JsepTransceiver& operator=(JsepTransceiver&& aRhs) = default;
-        mRecvTrack(orig.mRecvTrack),
-        mTransport(orig.mTransport),
-        mUuid(orig.mUuid),
-        mMid(orig.mMid),
-        mLevel(orig.mLevel),
-        mBundleLevel(orig.mBundleLevel),
-        mAddTrackMagic(orig.mAddTrackMagic),
-        mOnlyExistsBecauseOfSetRemote(orig.mOnlyExistsBecauseOfSetRemote),
-        mStopped(orig.mStopped),
-        mRemoved(orig.mRemoved),
-        mNegotiated(orig.mNegotiated),
-        mCanRecycle(orig.mCanRecycle) {}
 
-  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(JsepTransceiver);
+  ~JsepTransceiver() = default;
 
   void Rollback(JsepTransceiver& oldTransceiver, bool aRemote) {
     MOZ_ASSERT(oldTransceiver.GetMediaType() == GetMediaType());
@@ -130,6 +113,7 @@ class JsepTransceiver {
   void RestartDatachannelTransceiver() {
     MOZ_RELEASE_ASSERT(GetMediaType() == SdpMediaSection::kApplication);
     mStopped = false;
+    mCanRecycle = false;
   }
 
   void SetRemoved() { mRemoved = true; }

dom/webidl/PeerConnectionImpl.webidl

@@ -45,7 +45,8 @@ interface PeerConnectionImpl  {
   [Throws]
   RTCRtpTransceiver addTransceiver(RTCRtpTransceiverInit init,
                                    DOMString kind,
-                                   MediaStreamTrack? sendTrack);
+                                   MediaStreamTrack? sendTrack,
+                                   boolean addTrackMagic);
   sequence<RTCRtpTransceiver> getTransceivers();
 
   [Throws]

dom/webidl/RTCRtpTransceiver.webidl

@@ -38,8 +38,6 @@ interface RTCRtpTransceiver {
     // TODO: bug 1396922
     // undefined setCodecPreferences(sequence<RTCRtpCodecCapability> codecs);
 
-    [ChromeOnly]
-    undefined setAddTrackMagic();
     [ChromeOnly]
     undefined setDirectionInternal(RTCRtpTransceiverDirection direction);