Bug 1769802: Key JsepTransceiver by UUID instead of a simple integer index. r=mjf

The integer index we're replacing here is based on the order in which
transceivers were added. If we clone the JSEP engine for an sRD that happens to
result in the creation of a transceiver, and at the same time JS calls
addTransceiver, we have a situation where the sRD transceiver is added first
to the cloned JSEP engine, but the addTransceiver transceiver is added first
to the old JSEP engine, resulting in them having the same index. So, let's just
use a proper key for this stuff.

Differential Revision: https://phabricator.services.mozilla.com/D150169

dom/media/webrtc/jsapi/PeerConnectionImpl.cpp

@@ -851,8 +851,7 @@ nsresult PeerConnectionImpl::GetDatachannelParameters(
   transportId->clear();
 
   RefPtr<JsepTransceiver> datachannelTransceiver;
-  for (const auto& [id, transceiver] : mJsepSession->GetTransceivers()) {
+  for (const auto& transceiver : mJsepSession->GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     if ((transceiver->GetMediaType() == SdpMediaSection::kApplication) &&
         transceiver->mSendTrack.GetNegotiatedDetails()) {
       datachannelTransceiver = transceiver;
@@ -958,18 +957,8 @@ already_AddRefed<RTCRtpTransceiver> PeerConnectionImpl::AddTransceiver(
     return nullptr;
   }
 
-  RefPtr<JsepTransceiver> jsepTransceiver = new JsepTransceiver(*type);
+  RefPtr<JsepTransceiver> jsepTransceiver =
-
+      new JsepTransceiver(*type, *mUuidGen);
-  RefPtr<RTCRtpTransceiver> transceiver =
-      CreateTransceiver(jsepTransceiver, aInit, aSendTrack, aRv);
-
-  if (aRv.Failed()) {
-    // Would be nice if we could peek at the rv without stealing it, so we
-    // could log...
-    CSFLogError(LOGTAG, "%s: failed", __FUNCTION__);
-    return nullptr;
-  }
-
   jsepTransceiver->SetRtxIsAllowed(mRtxIsAllowed);
 
   // Do this last, since it is not possible to roll back.
@@ -981,6 +970,18 @@ already_AddRefed<RTCRtpTransceiver> PeerConnectionImpl::AddTransceiver(
     return nullptr;
   }
 
+  RefPtr<RTCRtpTransceiver> transceiver = CreateTransceiver(
+      jsepTransceiver->GetUuid(),
+      jsepTransceiver->GetMediaType() == SdpMediaSection::kVideo, aInit,
+      aSendTrack, aRv);
+
+  if (aRv.Failed()) {
+    // Would be nice if we could peek at the rv without stealing it, so we
+    // could log...
+    CSFLogError(LOGTAG, "%s: failed", __FUNCTION__);
+    return nullptr;
+  }
+
   mTransceivers.AppendElement(transceiver);
   return transceiver.forget();
 }
@@ -1073,8 +1074,7 @@ PeerConnectionImpl::CreateDataChannel(
   CSFLogDebug(LOGTAG, "%s: making DOMDataChannel", __FUNCTION__);
 
   RefPtr<JsepTransceiver> dcTransceiver;
-  for (auto& [id, transceiver] : mJsepSession->GetTransceivers()) {
+  for (auto& transceiver : mJsepSession->GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->GetMediaType() == SdpMediaSection::kApplication) {
       dcTransceiver = transceiver;
       break;
@@ -1082,8 +1082,8 @@ PeerConnectionImpl::CreateDataChannel(
   }
 
   if (!dcTransceiver) {
-    dcTransceiver =
+    dcTransceiver = new JsepTransceiver(
-        new JsepTransceiver(SdpMediaSection::MediaType::kApplication);
+        SdpMediaSection::MediaType::kApplication, *mUuidGen);
     mJsepSession->AddTransceiver(dcTransceiver);
   }
 
@@ -1609,25 +1609,37 @@ PeerConnectionImpl::SetRemoteDescription(int32_t action, const char* aSDP) {
     mPCObserver->OnSetDescriptionError(*buildJSErrorData(result, errorString),
                                        jrv);
   } else {
-    for (const auto& [id, jsepTransceiver] : mJsepSession->GetTransceivers()) {
+    for (const auto& jsepTransceiver : mJsepSession->GetTransceivers()) {
       if (jsepTransceiver->GetMediaType() ==
           SdpMediaSection::MediaType::kApplication) {
         continue;
       }
 
-      if (originalTransceivers.count(id)) {
+      CSFLogDebug(LOGTAG, "%s: Looking for match", __FUNCTION__);
-        continue;
+      RefPtr<RTCRtpTransceiver> transceiver;
+      for (auto& temp : mTransceivers) {
+        if (temp->GetJsepTransceiverId() == jsepTransceiver->GetUuid()) {
+          CSFLogDebug(LOGTAG, "%s: Found match", __FUNCTION__);
+          transceiver = temp;
+          break;
+        }
       }
 
-      dom::RTCRtpTransceiverInit init;
+      if (!transceiver) {
-      init.mDirection = RTCRtpTransceiverDirection::Recvonly;
+        CSFLogDebug(LOGTAG, "%s: No match, making new", __FUNCTION__);
-      RefPtr<RTCRtpTransceiver> transceiver =
+        dom::RTCRtpTransceiverInit init;
-          CreateTransceiver(jsepTransceiver, init, nullptr, jrv);
+        init.mDirection = RTCRtpTransceiverDirection::Recvonly;
-      if (jrv.Failed()) {
+        IgnoredErrorResult rv;
-        appendHistory();
+        transceiver = CreateTransceiver(
-        return NS_ERROR_FAILURE;
+            jsepTransceiver->GetUuid(),
+            jsepTransceiver->GetMediaType() == SdpMediaSection::kVideo, init,
+            nullptr, rv);
+        if (NS_WARN_IF(rv.Failed())) {
+          MOZ_ASSERT(false);
+          break;
+        }
+        mTransceivers.AppendElement(transceiver);
       }
-      mTransceivers.AppendElement(transceiver);
     }
 
     if (wasRestartingIce) {
@@ -3213,8 +3225,7 @@ bool PeerConnectionImpl::ShouldForceProxy() const {
 }
 
 void PeerConnectionImpl::EnsureTransports(const JsepSession& aSession) {
-  for (const auto& [id, transceiver] : aSession.GetTransceivers()) {
+  for (const auto& transceiver : aSession.GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->HasOwnTransport()) {
       mTransportHandler->EnsureProvisionalTransport(
           transceiver->mTransport.mTransportId,
@@ -3264,8 +3275,7 @@ void PeerConnectionImpl::RemoveRTCDtlsTransportsExcept(
 nsresult PeerConnectionImpl::UpdateTransports(const JsepSession& aSession,
                                               const bool forceIceTcp) {
   std::set<std::string> finalTransports;
-  for (const auto& [id, transceiver] : aSession.GetTransceivers()) {
+  for (const auto& transceiver : aSession.GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->HasOwnTransport()) {
       finalTransports.insert(transceiver->mTransport.mTransportId);
       UpdateTransport(*transceiver, forceIceTcp);
@@ -3636,7 +3646,7 @@ void PeerConnectionImpl::EnsureIceGathering(bool aDefaultRouteOnly,
 }
 
 already_AddRefed<dom::RTCRtpTransceiver> PeerConnectionImpl::CreateTransceiver(
-    JsepTransceiver* aJsepTransceiver, const RTCRtpTransceiverInit& aInit,
+    const std::string& aId, bool aIsVideo, const RTCRtpTransceiverInit& aInit,
     dom::MediaStreamTrack* aSendTrack, ErrorResult& aRv) {
   PeerConnectionCtx* ctx = PeerConnectionCtx::GetInstance();
   if (!mCall) {
@@ -3649,8 +3659,8 @@ already_AddRefed<dom::RTCRtpTransceiver> PeerConnectionImpl::CreateTransceiver(
   }
 
   RefPtr<RTCRtpTransceiver> transceiver = new RTCRtpTransceiver(
-      mWindow, PrivacyNeeded(), this, mTransportHandler, aJsepTransceiver,
+      mWindow, PrivacyNeeded(), this, mTransportHandler, mJsepSession.get(),
-      mSTSThread.get(), aSendTrack, mCall.get(), mIdGenerator);
+      aId, aIsVideo, mSTSThread.get(), aSendTrack, mCall.get(), mIdGenerator);
 
   transceiver->Init(aInit, aRv);
   if (aRv.Failed()) {

dom/media/webrtc/jsapi/PeerConnectionImpl.h

@@ -126,6 +126,9 @@ class RemoteSourceStreamInfo;
 class PCUuidGenerator : public mozilla::JsepUuidGenerator {
  public:
   virtual bool Generate(std::string* idp) override;
+  virtual mozilla::JsepUuidGenerator* Clone() const override {
+    return new PCUuidGenerator(*this);
+  }
 
  private:
   nsCOMPtr<nsIUUIDGenerator> mGenerator;
@@ -725,7 +728,7 @@ class PeerConnectionImpl final
   nsresult UpdateMediaPipelines();
 
   already_AddRefed<dom::RTCRtpTransceiver> CreateTransceiver(
-      JsepTransceiver* aJsepTransceiver,
+      const std::string& aId, bool aIsVideo,
       const dom::RTCRtpTransceiverInit& aInit,
       dom::MediaStreamTrack* aSendTrack, ErrorResult& aRv);
 

dom/media/webrtc/jsapi/RTCRtpTransceiver.cpp

@@ -156,13 +156,15 @@ NS_INTERFACE_MAP_END
 
 RTCRtpTransceiver::RTCRtpTransceiver(
     nsPIDOMWindowInner* aWindow, bool aPrivacyNeeded, PeerConnectionImpl* aPc,
-    MediaTransportHandler* aTransportHandler, JsepTransceiver* aJsepTransceiver,
+    MediaTransportHandler* aTransportHandler, JsepSession* aJsepSession,
+    const std::string& aTransceiverId, bool aIsVideo,
     nsISerialEventTarget* aStsThread, dom::MediaStreamTrack* aSendTrack,
     WebrtcCallWrapper* aCallWrapper, RTCStatsIdGenerator* aIdGenerator)
     : mWindow(aWindow),
       mPc(aPc),
       mTransportHandler(aTransportHandler),
-      mJsepTransceiver(aJsepTransceiver),
+      mTransceiverId(aTransceiverId),
+      mJsepTransceiver(aJsepSession->GetTransceiver(mTransceiverId)),
       mStsThread(aStsThread),
       mCallWrapper(aCallWrapper),
       mSendTrack(aSendTrack),

dom/media/webrtc/jsapi/RTCRtpTransceiver.h

@@ -12,7 +12,7 @@
 #include "nsTArray.h"
 #include "mozilla/dom/MediaStreamTrack.h"
 #include "ErrorList.h"
-#include "jsep/JsepTransceiver.h"
+#include "jsep/JsepSession.h"
 #include "transport/transportlayer.h"  // For TransportLayer::State
 #include "mozilla/dom/RTCRtpTransceiverBinding.h"
 
@@ -20,7 +20,6 @@ class nsIPrincipal;
 
 namespace mozilla {
 class PeerIdentity;
-class JsepTransceiver;
 class MediaSessionConduit;
 class VideoSessionConduit;
 class AudioSessionConduit;
@@ -58,14 +57,12 @@ class RTCRtpTransceiver : public nsISupports,
   /**
    * |aSendTrack| might or might not be set.
    */
-  RTCRtpTransceiver(nsPIDOMWindowInner* aWindow, bool aPrivacyNeeded,
+  RTCRtpTransceiver(
-                    PeerConnectionImpl* aPc,
+      nsPIDOMWindowInner* aWindow, bool aPrivacyNeeded, PeerConnectionImpl* aPc,
-                    MediaTransportHandler* aTransportHandler,
+      MediaTransportHandler* aTransportHandler, JsepSession* aJsepSession,
-                    JsepTransceiver* aJsepTransceiver,
+      const std::string& aTransceiverId, bool aIsVideo,
-                    nsISerialEventTarget* aStsThread,
+      nsISerialEventTarget* aStsThread, MediaStreamTrack* aSendTrack,
-                    MediaStreamTrack* aSendTrack,
+      WebrtcCallWrapper* aCallWrapper, RTCStatsIdGenerator* aIdGenerator);
-                    WebrtcCallWrapper* aCallWrapper,
-                    RTCStatsIdGenerator* aIdGenerator);
 
   void Init(const RTCRtpTransceiverInit& aInit, ErrorResult& aRv);
 
@@ -145,6 +142,8 @@ class RTCRtpTransceiver : public nsISupports,
 
   MediaSessionConduit* GetConduit() const { return mConduit; }
 
+  const std::string& GetJsepTransceiverId() const { return mTransceiverId; }
+
   // nsISupports
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(RTCRtpTransceiver)
@@ -188,7 +187,8 @@ class RTCRtpTransceiver : public nsISupports,
   nsCOMPtr<nsPIDOMWindowInner> mWindow;
   RefPtr<PeerConnectionImpl> mPc;
   RefPtr<MediaTransportHandler> mTransportHandler;
-  const RefPtr<JsepTransceiver> mJsepTransceiver;
+  const std::string mTransceiverId;
+  RefPtr<JsepTransceiver> mJsepTransceiver;
   nsCOMPtr<nsISerialEventTarget> mStsThread;
   // state for webrtc.org that is shared between all transceivers
   RefPtr<WebrtcCallWrapper> mCallWrapper;

dom/media/webrtc/jsep/JsepSession.h

@@ -107,8 +107,7 @@ class JsepSession {
   template <class UnaryFunction>
   void ForEachCodec(UnaryFunction& function) {
     std::for_each(Codecs().begin(), Codecs().end(), function);
-    for (auto& [id, transceiver] : GetTransceivers()) {
+    for (auto& transceiver : GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       transceiver->mSendTrack.ForEachCodec(function);
       transceiver->mRecvTrack.ForEachCodec(function);
     }
@@ -117,16 +116,24 @@ class JsepSession {
   template <class BinaryPredicate>
   void SortCodecs(BinaryPredicate& sorter) {
     std::stable_sort(Codecs().begin(), Codecs().end(), sorter);
-    for (auto& [id, transceiver] : GetTransceivers()) {
+    for (auto& transceiver : GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       transceiver->mSendTrack.SortCodecs(sorter);
       transceiver->mRecvTrack.SortCodecs(sorter);
     }
   }
 
-  virtual const std::map<size_t, RefPtr<JsepTransceiver>>& GetTransceivers()
+  // Returns transceivers in the order they were added.
+  virtual const std::vector<RefPtr<JsepTransceiver>>& GetTransceivers()
       const = 0;
-  virtual std::map<size_t, RefPtr<JsepTransceiver>>& GetTransceivers() = 0;
+  virtual std::vector<RefPtr<JsepTransceiver>>& GetTransceivers() = 0;
+  RefPtr<JsepTransceiver> GetTransceiver(const std::string& aId) const {
+    for (const auto& transceiver : GetTransceivers()) {
+      if (transceiver->GetUuid() == aId) {
+        return transceiver;
+      }
+    }
+    return nullptr;
+  }
   virtual nsresult AddTransceiver(RefPtr<JsepTransceiver> transceiver) = 0;
 
   class Result {
@@ -198,8 +205,7 @@ class JsepSession {
     memset(receiving, 0, sizeof(receiving));
     memset(sending, 0, sizeof(sending));
 
-    for (const auto& [id, transceiver] : GetTransceivers()) {
+    for (const auto& transceiver : GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (transceiver->mRecvTrack.GetActive() ||
           transceiver->GetMediaType() == SdpMediaSection::kApplication) {
         receiving[transceiver->mRecvTrack.GetMediaType()]++;

dom/media/webrtc/jsep/JsepSessionImpl.cpp

@@ -115,7 +115,8 @@ JsepSessionImpl::GetLocalIceCredentials() const {
 
 nsresult JsepSessionImpl::AddTransceiver(RefPtr<JsepTransceiver> transceiver) {
   mLastError.clear();
-  MOZ_MTLOG(ML_DEBUG, "[" << mName << "]: Adding transceiver.");
+  MOZ_MTLOG(ML_DEBUG,
+            "[" << mName << "]: Adding transceiver " << transceiver->GetUuid());
 
   if (transceiver->GetMediaType() != SdpMediaSection::kApplication) {
     // Make sure we have an ssrc. Might already be set.
@@ -126,6 +127,7 @@ nsresult JsepSessionImpl::AddTransceiver(RefPtr<JsepTransceiver> transceiver) {
     // (man I hate this)
     if (mEncodeTrackId) {
       std::string trackId;
+      // TODO: Maybe reuse the transceiver's UUID here?
       if (!mUuidGen->Generate(&trackId)) {
         JSEP_SET_ERROR("Failed to generate UUID for JsepTrack");
         return NS_ERROR_FAILURE;
@@ -138,8 +140,7 @@ nsresult JsepSessionImpl::AddTransceiver(RefPtr<JsepTransceiver> transceiver) {
     // of asserting.
     transceiver->mJsDirection = SdpDirectionAttribute::kSendrecv;
 #ifdef DEBUG
-    for (const auto& [id, transceiver] : mTransceivers) {
+    for (const auto& transceiver : mTransceivers) {
-      (void)id;  // Lame, but no better way to do this right now.
       MOZ_ASSERT(transceiver->GetMediaType() != SdpMediaSection::kApplication);
     }
 #endif
@@ -149,7 +150,7 @@ nsresult JsepSessionImpl::AddTransceiver(RefPtr<JsepTransceiver> transceiver) {
   transceiver->mRecvTrack.PopulateCodecs(mSupportedCodecs);
   // We do not set mLevel yet, we do that either on createOffer, or setRemote
 
-  mTransceivers[mTransceiverIdCounter++] = transceiver;
+  mTransceivers.push_back(transceiver);
   return NS_OK;
 }
 
@@ -802,8 +803,8 @@ JsepSession::Result JsepSessionImpl::SetLocalDescription(
   if (type == kJsepSdpOffer) {
     // Save in case we need to rollback
     mOldTransceivers.clear();
-    for (const auto& [id, transceiver] : mTransceivers) {
+    for (const auto& transceiver : mTransceivers) {
-      mOldTransceivers[id] = new JsepTransceiver(*transceiver);
+      mOldTransceivers.push_back(new JsepTransceiver(*transceiver));
     }
   }
 
@@ -1013,8 +1014,8 @@ JsepSession::Result JsepSessionImpl::SetRemoteDescription(
   // Save in case we need to rollback.
   if (type == kJsepSdpOffer) {
     mOldTransceivers.clear();
-    for (const auto& [id, transceiver] : mTransceivers) {
+    for (const auto& transceiver : mTransceivers) {
-      mOldTransceivers[id] = new JsepTransceiver(*transceiver);
+      mOldTransceivers.push_back(new JsepTransceiver(*transceiver));
       if (!transceiver->IsNegotiated()) {
         // We chose a level for this transceiver, but never negotiated it.
         // Discard this state.
@@ -1110,8 +1111,7 @@ nsresult JsepSessionImpl::HandleNegotiatedSession(
   CopyBundleTransports();
 
   std::vector<JsepTrack*> remoteTracks;
-  for (const auto& [id, transceiver] : mTransceivers) {
+  for (const auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     remoteTracks.push_back(&transceiver->mRecvTrack);
   }
   JsepTrack::SetUniquePayloadTypes(remoteTracks);
@@ -1215,8 +1215,7 @@ void JsepSessionImpl::EnsureHasOwnTransport(const SdpMediaSection& msection,
 }
 
 void JsepSessionImpl::CopyBundleTransports() {
-  for (auto& [id, transceiver] : mTransceivers) {
+  for (auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->HasBundleLevel()) {
       MOZ_MTLOG(ML_DEBUG,
                 "[" << mName << "] Transceiver " << transceiver->GetLevel()
@@ -1497,8 +1496,7 @@ nsresult JsepSessionImpl::SetRemoteDescriptionAnswer(JsepSdpType type,
 }
 
 JsepTransceiver* JsepSessionImpl::GetTransceiverForLevel(size_t level) const {
-  for (auto& [id, transceiver] : mTransceivers) {
+  for (const auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->HasLevel() && (transceiver->GetLevel() == level)) {
       return transceiver.get();
     }
@@ -1509,8 +1507,7 @@ JsepTransceiver* JsepSessionImpl::GetTransceiverForLevel(size_t level) const {
 
 JsepTransceiver* JsepSessionImpl::GetTransceiverForMid(
     const std::string& mid) const {
-  for (auto& [id, transceiver] : mTransceivers) {
+  for (const auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->IsAssociated() && (transceiver->GetMid() == mid)) {
       return transceiver.get();
     }
@@ -1540,8 +1537,7 @@ JsepTransceiver* JsepSessionImpl::GetTransceiverForLocal(size_t level) {
   // There is no transceiver for |level| right now.
 
   // Look for an RTP transceiver
-  for (auto& [id, transceiver] : mTransceivers) {
+  for (auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->GetMediaType() != SdpMediaSection::kApplication &&
         !transceiver->IsStopped() && !transceiver->HasLevel()) {
       transceiver->SetLevel(level);
@@ -1550,8 +1546,7 @@ JsepTransceiver* JsepSessionImpl::GetTransceiverForLocal(size_t level) {
   }
 
   // Ok, look for a datachannel
-  for (auto& [id, transceiver] : mTransceivers) {
+  for (auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (!transceiver->IsStopped() && !transceiver->HasLevel()) {
       transceiver->SetLevel(level);
       return transceiver.get();
@@ -1583,7 +1578,7 @@ JsepTransceiver* JsepSessionImpl::GetTransceiverForRemote(
 
   // Make a new transceiver
   RefPtr<JsepTransceiver> newTransceiver(new JsepTransceiver(
-      msection.GetMediaType(), SdpDirectionAttribute::kRecvonly));
+      msection.GetMediaType(), *mUuidGen, SdpDirectionAttribute::kRecvonly));
   newTransceiver->SetLevel(level);
   newTransceiver->SetCreatedBySetRemote();
   nsresult rv = AddTransceiver(newTransceiver);
@@ -1593,8 +1588,7 @@ JsepTransceiver* JsepSessionImpl::GetTransceiverForRemote(
 
 JsepTransceiver* JsepSessionImpl::GetTransceiverWithTransport(
     const std::string& transportId) const {
-  for (const auto& [id, transceiver] : mTransceivers) {
+  for (const auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->HasOwnTransport() &&
         (transceiver->mTransport.mTransportId == transportId)) {
       MOZ_ASSERT(transceiver->HasLevel(),
@@ -1657,8 +1651,7 @@ nsresult JsepSessionImpl::UpdateTransceiversFromRemoteDescription(
 JsepTransceiver* JsepSessionImpl::FindUnassociatedTransceiver(
     SdpMediaSection::MediaType type, bool magic) {
   // Look through transceivers that are not mapped to an m-section
-  for (auto& [id, transceiver] : mTransceivers) {
+  for (auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (type == SdpMediaSection::kApplication &&
         type == transceiver->GetMediaType()) {
       transceiver->RestartDatachannelTransceiver();
@@ -1675,30 +1668,32 @@ JsepTransceiver* JsepSessionImpl::FindUnassociatedTransceiver(
 }
 
 void JsepSessionImpl::RollbackLocalOffer() {
-  for (auto& [id, transceiver] : mTransceivers) {
+  for (size_t i = 0; i < mTransceivers.size(); ++i) {
-    if (mOldTransceivers.count(id)) {
+    auto transceiver = mTransceivers[i];
-      transceiver->Rollback(*mOldTransceivers[id], false);
+    if (mOldTransceivers.size() > i) {
-      mOldTransceivers[id] = transceiver;
+      transceiver->Rollback(*mOldTransceivers[i], false);
+      mOldTransceivers[i] = transceiver;
       continue;
     }
 
     RefPtr<JsepTransceiver> temp(
-        new JsepTransceiver(transceiver->GetMediaType()));
+        new JsepTransceiver(transceiver->GetMediaType(), *mUuidGen));
     temp->mSendTrack.PopulateCodecs(mSupportedCodecs);
     temp->mRecvTrack.PopulateCodecs(mSupportedCodecs);
     transceiver->Rollback(*temp, false);
-    mOldTransceivers[id] = transceiver;
+    mOldTransceivers.push_back(transceiver);
   }
 
   mTransceivers = std::move(mOldTransceivers);
 }
 
 void JsepSessionImpl::RollbackRemoteOffer() {
-  for (auto& [id, transceiver] : mTransceivers) {
+  for (size_t i = 0; i < mTransceivers.size(); ++i) {
-    if (mOldTransceivers.count(id)) {
+    auto transceiver = mTransceivers[i];
+    if (mOldTransceivers.size() > i) {
       // Some stuff cannot be rolled back. Save this information.
-      transceiver->Rollback(*mOldTransceivers[id], true);
+      transceiver->Rollback(*mOldTransceivers[i], true);
-      mOldTransceivers[id] = transceiver;
+      mOldTransceivers[i] = transceiver;
       continue;
     }
 
@@ -1709,7 +1704,7 @@ void JsepSessionImpl::RollbackRemoteOffer() {
     // We rollback even for transceivers we will remove, just to ensure we end
     // up at the starting state.
     RefPtr<JsepTransceiver> temp(
-        new JsepTransceiver(transceiver->GetMediaType()));
+        new JsepTransceiver(transceiver->GetMediaType(), *mUuidGen));
     temp->mSendTrack.PopulateCodecs(mSupportedCodecs);
     temp->mRecvTrack.PopulateCodecs(mSupportedCodecs);
     transceiver->Rollback(*temp, true);
@@ -1717,9 +1712,8 @@ void JsepSessionImpl::RollbackRemoteOffer() {
     if (shouldRemove) {
       transceiver->Stop();
       transceiver->SetRemoved();
-    } else {
-      mOldTransceivers[id] = transceiver;
     }
+    mOldTransceivers.push_back(transceiver);
   }
 
   mTransceivers = std::move(mOldTransceivers);
@@ -2287,8 +2281,7 @@ nsresult JsepSessionImpl::UpdateDefaultCandidate(
     return NS_ERROR_UNEXPECTED;
   }
 
-  for (const auto& [id, transceiver] : mTransceivers) {
+  for (const auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     // We set the default address for bundled m-sections, but not candidate
     // attributes. Ugh.
     if (transceiver->mTransport.mTransportId == transportId) {
@@ -2402,8 +2395,7 @@ JsepSessionImpl::GetLastSdpParsingErrors() const {
 bool JsepSessionImpl::CheckNegotiationNeeded() const {
   MOZ_ASSERT(mState == kJsepStateStable);
 
-  for (const auto& [id, transceiver] : mTransceivers) {
+  for (const auto& transceiver : mTransceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->IsStopped()) {
       if (transceiver->IsAssociated()) {
         MOZ_MTLOG(ML_DEBUG, "[" << mName

dom/media/webrtc/jsep/JsepSessionImpl.h

@@ -20,12 +20,6 @@
 
 namespace mozilla {
 
-class JsepUuidGenerator {
- public:
-  virtual ~JsepUuidGenerator() {}
-  virtual bool Generate(std::string* id) = 0;
-};
-
 class JsepSessionImpl : public JsepSession {
  public:
   JsepSessionImpl(const std::string& name, UniquePtr<JsepUuidGenerator> uuidgen)
@@ -138,13 +132,12 @@ class JsepSessionImpl : public JsepSession {
   virtual std::set<std::pair<std::string, std::string>> GetLocalIceCredentials()
       const override;
 
-  virtual const std::map<size_t, RefPtr<JsepTransceiver>>& GetTransceivers()
+  virtual const std::vector<RefPtr<JsepTransceiver>>& GetTransceivers()
       const override {
     return mTransceivers;
   }
 
-  virtual std::map<size_t, RefPtr<JsepTransceiver>>& GetTransceivers()
+  virtual std::vector<RefPtr<JsepTransceiver>>& GetTransceivers() override {
-      override {
     return mTransceivers;
   }
 
@@ -237,11 +230,10 @@ class JsepSessionImpl : public JsepSession {
   void SetIceRestarting(bool restarting);
 
   // !!!NOT INDEXED BY LEVEL!!! The level mapping is done with
-  // JsepTransceiver::mLevel. The keys are opaque, stable identifiers that are
+  // JsepTransceiver::mLevel. The keys are UUIDs.
-  // unique within the JsepSession.
+  std::vector<RefPtr<JsepTransceiver>> mTransceivers;
-  std::map<size_t, RefPtr<JsepTransceiver>> mTransceivers;
   // So we can rollback. Not as simple as just going back to the old, though...
-  std::map<size_t, RefPtr<JsepTransceiver>> mOldTransceivers;
+  std::vector<RefPtr<JsepTransceiver>> mOldTransceivers;
 
   Maybe<bool> mIsPendingOfferer;
   Maybe<bool> mIsCurrentOfferer;

dom/media/webrtc/jsep/JsepTransceiver.h

@@ -19,12 +19,20 @@
 
 namespace mozilla {
 
+class JsepUuidGenerator {
+ public:
+  virtual ~JsepUuidGenerator() = default;
+  virtual bool Generate(std::string* id) = 0;
+  virtual JsepUuidGenerator* Clone() const = 0;
+};
+
 class JsepTransceiver {
  private:
   ~JsepTransceiver(){};
 
  public:
   explicit JsepTransceiver(SdpMediaSection::MediaType type,
+                           JsepUuidGenerator& aUuidGen,
                            SdpDirectionAttribute::Direction jsDirection =
                                SdpDirectionAttribute::kSendrecv)
       : mJsDirection(jsDirection),
@@ -37,7 +45,11 @@ class JsepTransceiver {
         mStopped(false),
         mRemoved(false),
         mNegotiated(false),
-        mCanRecycle(false) {}
+        mCanRecycle(false) {
+    if (!aUuidGen.Generate(&mUuid)) {
+      MOZ_CRASH();
+    }
+  }
 
   // Can't use default copy c'tor because of the refcount members. Ugh.
   JsepTransceiver(const JsepTransceiver& orig)
@@ -45,6 +57,7 @@ class JsepTransceiver {
         mSendTrack(orig.mSendTrack),
         mRecvTrack(orig.mRecvTrack),
         mTransport(orig.mTransport),
+        mUuid(orig.mUuid),
         mMid(orig.mMid),
         mLevel(orig.mLevel),
         mBundleLevel(orig.mBundleLevel),
@@ -164,6 +177,8 @@ class JsepTransceiver {
 
   bool CanRecycle() const { return mCanRecycle; }
 
+  const std::string& GetUuid() const { return mUuid; }
+
   // Convenience function
   SdpMediaSection::MediaType GetMediaType() const {
     MOZ_ASSERT(mRecvTrack.GetMediaType() == mSendTrack.GetMediaType());
@@ -192,6 +207,7 @@ class JsepTransceiver {
   JsepTransport mTransport;
 
  private:
+  std::string mUuid;
   // Stuff that is not negotiated
   std::string mMid;
   size_t mLevel;  // SIZE_MAX if no level

media/webrtc/signaling/gtest/jsep_session_unittest.cpp

@@ -46,6 +46,10 @@ class FakeUuidGenerator : public mozilla::JsepUuidGenerator {
     return true;
   }
 
+  mozilla::JsepUuidGenerator* Clone() const {
+    return new FakeUuidGenerator(*this);
+  }
+
  private:
   static uint64_t ctr;
 };
@@ -100,13 +104,12 @@ class JsepSessionTest : public JsepSessionTestBase,
   }
 
   void CheckTransceiverInvariants(
-      const std::map<size_t, RefPtr<JsepTransceiver>>& oldTransceivers,
+      const std::vector<RefPtr<JsepTransceiver>>& oldTransceivers,
-      const std::map<size_t, RefPtr<JsepTransceiver>>& newTransceivers) {
+      const std::vector<RefPtr<JsepTransceiver>>& newTransceivers) {
     ASSERT_LE(oldTransceivers.size(), newTransceivers.size());
     std::set<size_t> levels;
 
-    for (const auto& [id, newTransceiver] : newTransceivers) {
+    for (const auto& newTransceiver : newTransceivers) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (newTransceiver->HasLevel()) {
         ASSERT_FALSE(levels.count(newTransceiver->GetLevel()))
         << "Two new transceivers are mapped to level "
@@ -124,8 +127,7 @@ class JsepSessionTest : public JsepSessionTestBase,
              "transceivers.";
     }
 
-    for (const auto& [id, oldTransceiver] : oldTransceivers) {
+    for (const auto& oldTransceiver : oldTransceivers) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (oldTransceiver->HasLevel()) {
         ASSERT_TRUE(levels.count(oldTransceiver->GetLevel()))
         << "Level " << oldTransceiver->GetLevel()
@@ -137,17 +139,18 @@ class JsepSessionTest : public JsepSessionTestBase,
     }
   }
 
-  std::map<size_t, RefPtr<JsepTransceiver>> DeepCopy(
+  std::vector<RefPtr<JsepTransceiver>> DeepCopy(
-      const std::map<size_t, RefPtr<JsepTransceiver>>& transceivers) {
+      const std::vector<RefPtr<JsepTransceiver>>& transceivers) {
-    std::map<size_t, RefPtr<JsepTransceiver>> copy;
+    std::vector<RefPtr<JsepTransceiver>> copy;
-    for (const auto& [id, transceiver] : transceivers) {
+    copy.reserve(transceivers.size());
-      copy[id] = new JsepTransceiver(*transceiver);
+    for (const auto& transceiver : transceivers) {
+      copy.push_back(new JsepTransceiver(*transceiver));
     }
     return copy;
   }
 
   std::string CreateOffer(const Maybe<JsepOfferOptions>& options = Nothing()) {
-    std::map<size_t, RefPtr<JsepTransceiver>> transceiversBefore =
+    std::vector<RefPtr<JsepTransceiver>> transceiversBefore =
         DeepCopy(mSessionOff->GetTransceivers());
     JsepOfferOptions defaultOptions;
     const JsepOfferOptions& optionsRef = options ? *options : defaultOptions;
@@ -267,11 +270,10 @@ class JsepSessionTest : public JsepSessionTestBase,
   void AddTracks(JsepSessionImpl& side,
                  const std::vector<SdpMediaSection::MediaType>& mediatypes,
                  AddTrackMagic magic = ADDTRACK_MAGIC) {
-    FakeUuidGenerator uuid_gen;
     std::string stream_id;
     std::string track_id;
 
-    ASSERT_TRUE(uuid_gen.Generate(&stream_id));
+    ASSERT_TRUE(mUuidGen.Generate(&stream_id));
 
     AddTracksToStream(side, stream_id, mediatypes, magic);
   }
@@ -296,16 +298,16 @@ class JsepSessionTest : public JsepSessionTestBase,
       AddTrackMagic magic = ADDTRACK_MAGIC)
 
   {
-    FakeUuidGenerator uuid_gen;
     std::string track_id;
 
     for (auto type : mediatypes) {
-      ASSERT_TRUE(uuid_gen.Generate(&track_id));
+      ASSERT_TRUE(mUuidGen.Generate(&track_id));
 
       RefPtr<JsepTransceiver> suitableTransceiver;
       size_t i;
       if (magic == ADDTRACK_MAGIC) {
-        for (auto& [id, transceiver] : side.GetTransceivers()) {
+        for (i = 0; i < side.GetTransceivers().size(); ++i) {
+          auto transceiver = side.GetTransceivers()[i];
           if (transceiver->mSendTrack.GetMediaType() != type) {
             continue;
           }
@@ -313,16 +315,15 @@ class JsepSessionTest : public JsepSessionTestBase,
           if (IsNull(transceiver->mSendTrack) ||
               transceiver->GetMediaType() == SdpMediaSection::kApplication) {
             suitableTransceiver = transceiver;
-            i = id;
             break;
           }
         }
       }
 
       if (!suitableTransceiver) {
-        suitableTransceiver = new JsepTransceiver(type);
+        i = side.GetTransceivers().size();
+        suitableTransceiver = new JsepTransceiver(type, mUuidGen);
         side.AddTransceiver(suitableTransceiver);
-        i = side.GetTransceivers().rbegin()->first;
       }
 
       std::cerr << "Updating send track for transceiver " << i << std::endl;
@@ -352,8 +353,7 @@ class JsepSessionTest : public JsepSessionTestBase,
 
   std::vector<JsepTrack> GetLocalTracks(const JsepSession& session) const {
     std::vector<JsepTrack> result;
-    for (const auto& [id, transceiver] : session.GetTransceivers()) {
+    for (const auto& transceiver : session.GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (!IsNull(transceiver->mSendTrack)) {
         result.push_back(transceiver->mSendTrack);
       }
@@ -363,8 +363,7 @@ class JsepSessionTest : public JsepSessionTestBase,
 
   std::vector<JsepTrack> GetRemoteTracks(const JsepSession& session) const {
     std::vector<JsepTrack> result;
-    for (const auto& [id, transceiver] : session.GetTransceivers()) {
+    for (const auto& transceiver : session.GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (!IsNull(transceiver->mRecvTrack)) {
         result.push_back(transceiver->mRecvTrack);
       }
@@ -373,8 +372,7 @@ class JsepSessionTest : public JsepSessionTestBase,
   }
 
   JsepTransceiver* GetDatachannelTransceiver(JsepSession& side) {
-    for (const auto& [id, transceiver] : side.GetTransceivers()) {
+    for (const auto& transceiver : side.GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (transceiver->mSendTrack.GetMediaType() ==
           SdpMediaSection::MediaType::kApplication) {
         return transceiver.get();
@@ -385,8 +383,7 @@ class JsepSessionTest : public JsepSessionTestBase,
   }
 
   JsepTransceiver* GetNegotiatedTransceiver(JsepSession& side, size_t index) {
-    for (const auto& [id, transceiver] : side.GetTransceivers()) {
+    for (const auto& transceiver : side.GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (transceiver->mSendTrack.GetNegotiatedDetails() ||
           transceiver->mRecvTrack.GetNegotiatedDetails()) {
         if (index) {
@@ -402,10 +399,8 @@ class JsepSessionTest : public JsepSessionTestBase,
   }
 
   JsepTransceiver* GetTransceiverByLevel(
-      const std::map<size_t, RefPtr<JsepTransceiver>>& transceivers,
+      const std::vector<RefPtr<JsepTransceiver>>& transceivers, size_t level) {
-      size_t level) {
+    for (const auto& transceiver : transceivers) {
-    for (const auto& [id, transceiver] : transceivers) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (transceiver->HasLevel() && transceiver->GetLevel() == level) {
         return transceiver.get();
       }
@@ -461,8 +456,7 @@ class JsepSessionTest : public JsepSessionTestBase,
 
   JsepTrack GetTrack(JsepSessionImpl& side, SdpMediaSection::MediaType type,
                      size_t index) const {
-    for (const auto& [id, transceiver] : side.GetTransceivers()) {
+    for (const auto& transceiver : side.GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (IsNull(transceiver->mSendTrack) ||
           transceiver->mSendTrack.GetMediaType() != type) {
         continue;
@@ -655,19 +649,16 @@ class JsepSessionTest : public JsepSessionTestBase,
     return true;
   }
 
-  bool Equals(const std::map<size_t, RefPtr<JsepTransceiver>>& t1,
+  bool Equals(const std::vector<RefPtr<JsepTransceiver>>& t1,
-              const std::map<size_t, RefPtr<JsepTransceiver>>& t2) const {
+              const std::vector<RefPtr<JsepTransceiver>>& t2) const {
     if (t1.size() != t2.size()) {
       std::cerr << "Size differs: t1.size = " << t1.size()
                 << ", t2.size = " << t2.size() << std::endl;
       return false;
     }
 
-    for (const auto& [id, transceiver] : t1) {
+    for (size_t i = 0; i < t1.size(); ++i) {
-      if (!t2.count(id)) {
+      if (!Equals(*t1[i], *t2[i])) {
-        return false;
-      }
-      if (!Equals(*transceiver, *t2.at(id))) {
         return false;
       }
     }
@@ -743,7 +734,7 @@ class JsepSessionTest : public JsepSessionTestBase,
   }
 
   std::string CreateAnswer() {
-    std::map<size_t, RefPtr<JsepTransceiver>> transceiversBefore =
+    std::vector<RefPtr<JsepTransceiver>> transceiversBefore =
         DeepCopy(mSessionAns->GetTransceivers());
 
     JsepAnswerOptions options;
@@ -779,7 +770,7 @@ class JsepSessionTest : public JsepSessionTestBase,
 
   void SetLocalOffer(const std::string& offer,
                      uint32_t checkFlags = ALL_CHECKS) {
-    std::map<size_t, RefPtr<JsepTransceiver>> transceiversBefore =
+    std::vector<RefPtr<JsepTransceiver>> transceiversBefore =
         DeepCopy(mSessionOff->GetTransceivers());
 
     JsepSession::Result result =
@@ -795,8 +786,7 @@ class JsepSessionTest : public JsepSessionTestBase,
     if (checkFlags & CHECK_TRACKS) {
       // This assumes no recvonly or inactive transceivers.
       ASSERT_EQ(types.size(), mSessionOff->GetTransceivers().size());
-      for (const auto& [id, transceiver] : mSessionOff->GetTransceivers()) {
+      for (const auto& transceiver : mSessionOff->GetTransceivers()) {
-        (void)id;  // Lame, but no better way to do this right now.
         if (!transceiver->HasLevel()) {
           continue;
         }
@@ -820,7 +810,7 @@ class JsepSessionTest : public JsepSessionTestBase,
 
   void SetRemoteOffer(const std::string& offer,
                       uint32_t checkFlags = ALL_CHECKS) {
-    std::map<size_t, RefPtr<JsepTransceiver>> transceiversBefore =
+    std::vector<RefPtr<JsepTransceiver>> transceiversBefore =
         DeepCopy(mSessionAns->GetTransceivers());
 
     JsepSession::Result result =
@@ -836,8 +826,7 @@ class JsepSessionTest : public JsepSessionTestBase,
     if (checkFlags & CHECK_TRACKS) {
       // This assumes no recvonly or inactive transceivers.
       ASSERT_EQ(types.size(), mSessionAns->GetTransceivers().size());
-      for (const auto& [id, transceiver] : mSessionAns->GetTransceivers()) {
+      for (const auto& transceiver : mSessionAns->GetTransceivers()) {
-        (void)id;  // Lame, but no better way to do this right now.
         if (!transceiver->HasLevel()) {
           continue;
         }
@@ -858,7 +847,7 @@ class JsepSessionTest : public JsepSessionTestBase,
 
   void SetLocalAnswer(const std::string& answer,
                       uint32_t checkFlags = ALL_CHECKS) {
-    std::map<size_t, RefPtr<JsepTransceiver>> transceiversBefore =
+    std::vector<RefPtr<JsepTransceiver>> transceiversBefore =
         DeepCopy(mSessionAns->GetTransceivers());
 
     JsepSession::Result result =
@@ -873,8 +862,7 @@ class JsepSessionTest : public JsepSessionTestBase,
     if (checkFlags & CHECK_TRACKS) {
       // Verify that the right stuff is in the tracks.
       ASSERT_EQ(types.size(), mSessionAns->GetTransceivers().size());
-      for (const auto& [id, transceiver] : mSessionAns->GetTransceivers()) {
+      for (const auto& transceiver : mSessionAns->GetTransceivers()) {
-        (void)id;  // Lame, but no better way to do this right now.
         if (!transceiver->HasLevel()) {
           continue;
         }
@@ -906,7 +894,7 @@ class JsepSessionTest : public JsepSessionTestBase,
 
   void SetRemoteAnswer(const std::string& answer,
                        uint32_t checkFlags = ALL_CHECKS) {
-    std::map<size_t, RefPtr<JsepTransceiver>> transceiversBefore =
+    std::vector<RefPtr<JsepTransceiver>> transceiversBefore =
         DeepCopy(mSessionOff->GetTransceivers());
 
     JsepSession::Result result =
@@ -921,8 +909,7 @@ class JsepSessionTest : public JsepSessionTestBase,
     if (checkFlags & CHECK_TRACKS) {
       // Verify that the right stuff is in the tracks.
       ASSERT_EQ(types.size(), mSessionOff->GetTransceivers().size());
-      for (const auto& [id, transceiver] : mSessionOff->GetTransceivers()) {
+      for (const auto& transceiver : mSessionOff->GetTransceivers()) {
-        (void)id;  // Lame, but no better way to do this right now.
         if (!transceiver->HasLevel()) {
           continue;
         }
@@ -950,8 +937,7 @@ class JsepSessionTest : public JsepSessionTestBase,
   }
 
   std::string GetTransportId(const JsepSession& session, size_t level) {
-    for (const auto& [id, transceiver] : session.GetTransceivers()) {
+    for (const auto& transceiver : session.GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       if (transceiver->HasLevel() && transceiver->GetLevel() == level) {
         return transceiver->mTransport.mTransportId;
       }
@@ -966,8 +952,7 @@ class JsepSessionTest : public JsepSessionTestBase,
     CandidateSet() {}
 
     void Gather(JsepSession& session, ComponentType maxComponent = RTCP) {
-      for (const auto& [id, transceiver] : session.GetTransceivers()) {
+      for (const auto& transceiver : session.GetTransceivers()) {
-        (void)id;  // Lame, but no better way to do this right now.
         if (transceiver->HasOwnTransport()) {
           Gather(session, transceiver->mTransport.mTransportId, RTP);
           if (transceiver->mTransport.mComponents > 1) {
@@ -1199,8 +1184,7 @@ class JsepSessionTest : public JsepSessionTestBase,
 
   void CheckTransceiversAreBundled(const JsepSession& session,
                                    const std::string& context) {
-    for (const auto& [id, transceiver] : session.GetTransceivers()) {
+    for (const auto& transceiver : session.GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       ASSERT_TRUE(transceiver->HasBundleLevel())
       << context;
       ASSERT_EQ(0U, transceiver->BundleLevel()) << context;
@@ -1357,8 +1341,7 @@ class JsepSessionTest : public JsepSessionTestBase,
   }
 
   void DumpTransceivers(const JsepSessionImpl& session) {
-    for (const auto& [id, transceiver] : session.GetTransceivers()) {
+    for (const auto& transceiver : session.GetTransceivers()) {
-      (void)id;  // Lame, but no better way to do this right now.
       std::cerr << "Transceiver ";
       if (transceiver->HasLevel()) {
         std::cerr << transceiver->GetLevel() << std::endl;
@@ -1405,6 +1388,8 @@ class JsepSessionTest : public JsepSessionTestBase,
   std::vector<SdpMediaSection::MediaType> types;
   std::vector<std::pair<std::string, uint16_t>> mGatheredCandidates;
 
+  FakeUuidGenerator mUuidGen;
+
  private:
   void ValidateTransport(TransportData& source, const std::string& sdp_str,
                          sdp::SdpType type) {
@@ -1596,9 +1581,9 @@ TEST_P(JsepSessionTest, RenegotiationNoChange) {
   ValidateSetupAttribute(*mSessionOff, SdpSetupAttribute::kActpass);
   ValidateSetupAttribute(*mSessionAns, SdpSetupAttribute::kActive);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   std::string reoffer = CreateOffer();
@@ -1657,8 +1642,8 @@ TEST_P(JsepSessionTest, DISABLED_RenegotiationSwappedRolesNoChange) {
   ASSERT_TRUE(Equals(answererTransceivers, newOffererTransceivers));
 }
 
-static void RemoveLastN(
+static void RemoveLastN(std::vector<RefPtr<JsepTransceiver>>& aTransceivers,
-    std::map<size_t, RefPtr<JsepTransceiver>>& aTransceivers, size_t aNum) {
+                        size_t aNum) {
   while (aNum--) {
     // erase doesn't take reverse_iterator :(
     aTransceivers.erase(--aTransceivers.end());
@@ -1674,9 +1659,9 @@ TEST_P(JsepSessionTest, RenegotiationOffererAddsTrack) {
   ValidateSetupAttribute(*mSessionOff, SdpSetupAttribute::kActpass);
   ValidateSetupAttribute(*mSessionAns, SdpSetupAttribute::kActive);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   std::vector<SdpMediaSection::MediaType> extraTypes;
@@ -1711,9 +1696,9 @@ TEST_P(JsepSessionTest, RenegotiationAnswererAddsTrack) {
   ValidateSetupAttribute(*mSessionOff, SdpSetupAttribute::kActpass);
   ValidateSetupAttribute(*mSessionAns, SdpSetupAttribute::kActive);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   std::vector<SdpMediaSection::MediaType> extraTypes;
@@ -1723,10 +1708,12 @@ TEST_P(JsepSessionTest, RenegotiationAnswererAddsTrack) {
   types.insert(types.end(), extraTypes.begin(), extraTypes.end());
 
   // We need to add a recvonly m-section to the offer for this to work
-  mSessionOff->AddTransceiver(new JsepTransceiver(
+  mSessionOff->AddTransceiver(
-      SdpMediaSection::kAudio, SdpDirectionAttribute::Direction::kRecvonly));
+      new JsepTransceiver(SdpMediaSection::kAudio, mUuidGen,
-  mSessionOff->AddTransceiver(new JsepTransceiver(
+                          SdpDirectionAttribute::Direction::kRecvonly));
-      SdpMediaSection::kVideo, SdpDirectionAttribute::Direction::kRecvonly));
+  mSessionOff->AddTransceiver(
+      new JsepTransceiver(SdpMediaSection::kVideo, mUuidGen,
+                          SdpDirectionAttribute::Direction::kRecvonly));
 
   std::string offer = CreateOffer();
   SetLocalOffer(offer, CHECK_SUCCESS);
@@ -1760,9 +1747,9 @@ TEST_P(JsepSessionTest, RenegotiationBothAddTrack) {
   ValidateSetupAttribute(*mSessionOff, SdpSetupAttribute::kActpass);
   ValidateSetupAttribute(*mSessionAns, SdpSetupAttribute::kActive);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   std::vector<SdpMediaSection::MediaType> extraTypes;
@@ -1923,12 +1910,12 @@ TEST_P(JsepSessionTest, RenegotiationOffererStopsTransceiver) {
 
   OfferAnswer();
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
-  auto lastTransceiver = mSessionOff->GetTransceivers().rbegin()->second;
+  auto lastTransceiver = mSessionOff->GetTransceivers().back();
   // Avoid bundle transport side effects; don't stop the BUNDLE-tag!
   lastTransceiver->Stop();
   JsepTrack removedTrack(lastTransceiver->mSendTrack);
@@ -1953,11 +1940,11 @@ TEST_P(JsepSessionTest, RenegotiationOffererStopsTransceiver) {
 
   ASSERT_EQ(origOffererTransceivers.size(), newOffererTransceivers.size());
 
-  ASSERT_FALSE(origOffererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_FALSE(origOffererTransceivers.back()->IsStopped());
-  ASSERT_TRUE(newOffererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_TRUE(newOffererTransceivers.back()->IsStopped());
 
-  ASSERT_FALSE(origAnswererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_FALSE(origAnswererTransceivers.back()->IsStopped());
-  ASSERT_TRUE(newAnswererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_TRUE(newAnswererTransceivers.back()->IsStopped());
   RemoveLastN(origOffererTransceivers, 1);   // Ignore this one
   RemoveLastN(newOffererTransceivers, 1);    // Ignore this one
   RemoveLastN(origAnswererTransceivers, 1);  // Ignore this one
@@ -1976,15 +1963,14 @@ TEST_P(JsepSessionTest, RenegotiationAnswererStopsTransceiver) {
 
   OfferAnswer();
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   // Avoid bundle transport side effects; don't stop the BUNDLE-tag!
-  mSessionAns->GetTransceivers().rbegin()->second->Stop();
+  mSessionAns->GetTransceivers().back()->Stop();
-  JsepTrack removedTrack(
+  JsepTrack removedTrack(mSessionAns->GetTransceivers().back()->mSendTrack);
-      mSessionAns->GetTransceivers().rbegin()->second->mSendTrack);
 
   OfferAnswer(CHECK_SUCCESS);
 
@@ -2007,10 +1993,10 @@ TEST_P(JsepSessionTest, RenegotiationAnswererStopsTransceiver) {
 
   ASSERT_EQ(origOffererTransceivers.size(), newOffererTransceivers.size());
 
-  ASSERT_FALSE(origOffererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_FALSE(origOffererTransceivers.back()->IsStopped());
-  ASSERT_TRUE(newOffererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_TRUE(newOffererTransceivers.back()->IsStopped());
-  ASSERT_FALSE(origAnswererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_FALSE(origAnswererTransceivers.back()->IsStopped());
-  ASSERT_TRUE(newAnswererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_TRUE(newAnswererTransceivers.back()->IsStopped());
   RemoveLastN(origOffererTransceivers, 1);   // Ignore this one
   RemoveLastN(newOffererTransceivers, 1);    // Ignore this one
   RemoveLastN(origAnswererTransceivers, 1);  // Ignore this one
@@ -2029,18 +2015,18 @@ TEST_P(JsepSessionTest, RenegotiationBothStopSameTransceiver) {
 
   OfferAnswer();
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   // Avoid bundle transport side effects; don't stop the BUNDLE-tag!
-  mSessionOff->GetTransceivers().rbegin()->second->Stop();
+  mSessionOff->GetTransceivers().back()->Stop();
   JsepTrack removedTrackOffer(
-      mSessionOff->GetTransceivers().rbegin()->second->mSendTrack);
+      mSessionOff->GetTransceivers().back()->mSendTrack);
-  mSessionAns->GetTransceivers().rbegin()->second->Stop();
+  mSessionAns->GetTransceivers().back()->Stop();
   JsepTrack removedTrackAnswer(
-      mSessionAns->GetTransceivers().rbegin()->second->mSendTrack);
+      mSessionAns->GetTransceivers().back()->mSendTrack);
 
   OfferAnswer(CHECK_SUCCESS);
 
@@ -2062,10 +2048,10 @@ TEST_P(JsepSessionTest, RenegotiationBothStopSameTransceiver) {
 
   ASSERT_EQ(origOffererTransceivers.size(), newOffererTransceivers.size());
 
-  ASSERT_FALSE(origOffererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_FALSE(origOffererTransceivers.back()->IsStopped());
-  ASSERT_TRUE(newOffererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_TRUE(newOffererTransceivers.back()->IsStopped());
-  ASSERT_FALSE(origAnswererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_FALSE(origAnswererTransceivers.back()->IsStopped());
-  ASSERT_TRUE(newAnswererTransceivers.rbegin()->second->IsStopped());
+  ASSERT_TRUE(newAnswererTransceivers.back()->IsStopped());
   RemoveLastN(origOffererTransceivers, 1);   // Ignore this one
   RemoveLastN(newOffererTransceivers, 1);    // Ignore this one
   RemoveLastN(origAnswererTransceivers, 1);  // Ignore this one
@@ -2087,18 +2073,18 @@ TEST_P(JsepSessionTest, RenegotiationBothStopTransceiverThenAddTrack) {
   OfferAnswer();
 
   // Avoid bundle transport side effects; don't stop the BUNDLE-tag!
-  mSessionOff->GetTransceivers().rbegin()->second->Stop();
+  mSessionOff->GetTransceivers().back()->Stop();
   JsepTrack removedTrackOffer(
-      mSessionOff->GetTransceivers().rbegin()->second->mSendTrack);
+      mSessionOff->GetTransceivers().back()->mSendTrack);
-  mSessionOff->GetTransceivers().rbegin()->second->Stop();
+  mSessionOff->GetTransceivers().back()->Stop();
   JsepTrack removedTrackAnswer(
-      mSessionOff->GetTransceivers().rbegin()->second->mSendTrack);
+      mSessionOff->GetTransceivers().back()->mSendTrack);
 
   OfferAnswer(CHECK_SUCCESS);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   std::vector<SdpMediaSection::MediaType> extraTypes;
@@ -2117,11 +2103,11 @@ TEST_P(JsepSessionTest, RenegotiationBothStopTransceiverThenAddTrack) {
             newAnswererTransceivers.size());
 
   // Ensure that the m-section was re-used; no gaps
-  ASSERT_EQ(origOffererTransceivers.rbegin()->second->GetLevel(),
+  ASSERT_EQ(origOffererTransceivers.back()->GetLevel(),
-            newOffererTransceivers.rbegin()->second->GetLevel());
+            newOffererTransceivers.back()->GetLevel());
 
-  ASSERT_EQ(origAnswererTransceivers.rbegin()->second->GetLevel(),
+  ASSERT_EQ(origAnswererTransceivers.back()->GetLevel(),
-            newAnswererTransceivers.rbegin()->second->GetLevel());
+            newAnswererTransceivers.back()->GetLevel());
 }
 
 TEST_P(JsepSessionTest, RenegotiationBothStopTransceiverDifferentMsection) {
@@ -2204,9 +2190,9 @@ TEST_P(JsepSessionTest, RenegotiationAutoAssignedMsidIsStable) {
 
   SetRemoteAnswer(answer, CHECK_SUCCESS);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   ASSERT_EQ(origOffererTransceivers.size(), origAnswererTransceivers.size());
@@ -2241,8 +2227,7 @@ TEST_P(JsepSessionTest, RenegotiationOffererDisablesTelephoneEvent) {
   // check all the audio tracks to make sure they have 2 codecs (109 and 101),
   // and dtmf is enabled on all audio tracks
   std::vector<JsepTrack> tracks;
-  for (const auto& [id, transceiver] : mSessionOff->GetTransceivers()) {
+  for (const auto& transceiver : mSessionOff->GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     tracks.push_back(transceiver->mSendTrack);
     tracks.push_back(transceiver->mRecvTrack);
   }
@@ -2281,8 +2266,7 @@ TEST_P(JsepSessionTest, RenegotiationOffererDisablesTelephoneEvent) {
   // check all the audio tracks to make sure they have 1 codec (109),
   // and dtmf is disabled on all audio tracks
   tracks.clear();
-  for (const auto& [id, transceiver] : mSessionOff->GetTransceivers()) {
+  for (const auto& transceiver : mSessionOff->GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     tracks.push_back(transceiver->mSendTrack);
     tracks.push_back(transceiver->mRecvTrack);
   }
@@ -2320,9 +2304,9 @@ TEST_P(JsepSessionTest, RenegotiationAnswererEnablesMsid) {
 
   SetRemoteAnswer(answer, CHECK_SUCCESS);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   offer = CreateOffer();
@@ -2366,9 +2350,9 @@ TEST_P(JsepSessionTest, RenegotiationAnswererDisablesMsid) {
   SetLocalAnswer(answer);
   SetRemoteAnswer(answer, CHECK_SUCCESS);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   offer = CreateOffer();
@@ -2426,9 +2410,9 @@ TEST_P(JsepSessionTest, RenegotiationOffererEnablesBundle) {
   SetLocalAnswer(answer);
   SetRemoteAnswer(answer);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   OfferAnswer();
@@ -2473,9 +2457,9 @@ TEST_P(JsepSessionTest, RenegotiationOffererDisablesBundleTransport) {
 
   GetTransceiverByLevel(*mSessionOff, 0)->Stop();
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   OfferAnswer(CHECK_SUCCESS);
@@ -2524,9 +2508,9 @@ TEST_P(JsepSessionTest, RenegotiationAnswererDisablesBundleTransport) {
 
   OfferAnswer();
 
-  std::map<size_t, RefPtr<JsepTransceiver>> origOffererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origOffererTransceivers =
       DeepCopy(mSessionOff->GetTransceivers());
-  std::map<size_t, RefPtr<JsepTransceiver>> origAnswererTransceivers =
+  std::vector<RefPtr<JsepTransceiver>> origAnswererTransceivers =
       DeepCopy(mSessionAns->GetTransceivers());
 
   GetTransceiverByLevel(*mSessionAns, 0)->Stop();
@@ -3035,11 +3019,11 @@ INSTANTIATE_TEST_SUITE_P(
 
 TEST_F(JsepSessionTest, OfferAnswerRecvOnlyLines) {
   mSessionOff->AddTransceiver(new JsepTransceiver(
-      SdpMediaSection::kAudio, SdpDirectionAttribute::kRecvonly));
+      SdpMediaSection::kAudio, mUuidGen, SdpDirectionAttribute::kRecvonly));
   mSessionOff->AddTransceiver(new JsepTransceiver(
-      SdpMediaSection::kVideo, SdpDirectionAttribute::kRecvonly));
+      SdpMediaSection::kVideo, mUuidGen, SdpDirectionAttribute::kRecvonly));
   mSessionOff->AddTransceiver(new JsepTransceiver(
-      SdpMediaSection::kVideo, SdpDirectionAttribute::kRecvonly));
+      SdpMediaSection::kVideo, mUuidGen, SdpDirectionAttribute::kRecvonly));
   std::string offer = CreateOffer();
 
   UniquePtr<Sdp> parsedOffer(Parse(offer));
@@ -3099,11 +3083,10 @@ TEST_F(JsepSessionTest, OfferAnswerRecvOnlyLines) {
   SetLocalAnswer(answer, CHECK_SUCCESS);
   SetRemoteAnswer(answer, CHECK_SUCCESS);
 
-  std::map<size_t, RefPtr<JsepTransceiver>> transceivers(
+  std::vector<RefPtr<JsepTransceiver>> transceivers(
       mSessionOff->GetTransceivers());
   ASSERT_EQ(3U, transceivers.size());
-  for (const auto& [id, transceiver] : transceivers) {
+  for (const auto& transceiver : transceivers) {
-    (void)id;  // Lame, but no better way to do this right now.
     const auto& msection =
         parsedOffer->GetMediaSection(transceiver->GetLevel());
     const auto& ssrcs = msection.GetAttributeList().GetSsrc().mSsrcs;
@@ -3167,7 +3150,7 @@ TEST_F(JsepSessionTest, OfferAnswerSendOnlyLines) {
 
 TEST_F(JsepSessionTest, OfferToReceiveAudioNotUsed) {
   mSessionOff->AddTransceiver(new JsepTransceiver(
-      SdpMediaSection::kAudio, SdpDirectionAttribute::kRecvonly));
+      SdpMediaSection::kAudio, mUuidGen, SdpDirectionAttribute::kRecvonly));
 
   OfferAnswer(CHECK_SUCCESS);
 
@@ -3190,7 +3173,7 @@ TEST_F(JsepSessionTest, OfferToReceiveAudioNotUsed) {
 
 TEST_F(JsepSessionTest, OfferToReceiveVideoNotUsed) {
   mSessionOff->AddTransceiver(new JsepTransceiver(
-      SdpMediaSection::kVideo, SdpDirectionAttribute::kRecvonly));
+      SdpMediaSection::kVideo, mUuidGen, SdpDirectionAttribute::kRecvonly));
 
   OfferAnswer(CHECK_SUCCESS);
 
@@ -3212,12 +3195,14 @@ TEST_F(JsepSessionTest, OfferToReceiveVideoNotUsed) {
 }
 
 TEST_F(JsepSessionTest, CreateOfferNoDatachannelDefault) {
-  RefPtr<JsepTransceiver> audio(new JsepTransceiver(SdpMediaSection::kAudio));
+  RefPtr<JsepTransceiver> audio(
+      new JsepTransceiver(SdpMediaSection::kAudio, mUuidGen));
   audio->mSendTrack.UpdateStreamIds(
       std::vector<std::string>(1, "offerer_stream"));
   mSessionOff->AddTransceiver(audio);
 
-  RefPtr<JsepTransceiver> video(new JsepTransceiver(SdpMediaSection::kVideo));
+  RefPtr<JsepTransceiver> video(
+      new JsepTransceiver(SdpMediaSection::kVideo, mUuidGen));
   video->mSendTrack.UpdateStreamIds(
       std::vector<std::string>(1, "offerer_stream"));
   mSessionOff->AddTransceiver(video);
@@ -3238,12 +3223,14 @@ TEST_F(JsepSessionTest, ValidateOfferedVideoCodecParams) {
   types.push_back(SdpMediaSection::kAudio);
   types.push_back(SdpMediaSection::kVideo);
 
-  RefPtr<JsepTransceiver> audio(new JsepTransceiver(SdpMediaSection::kAudio));
+  RefPtr<JsepTransceiver> audio(
+      new JsepTransceiver(SdpMediaSection::kAudio, mUuidGen));
   audio->mSendTrack.UpdateStreamIds(
       std::vector<std::string>(1, "offerer_stream"));
   mSessionOff->AddTransceiver(audio);
 
-  RefPtr<JsepTransceiver> video(new JsepTransceiver(SdpMediaSection::kVideo));
+  RefPtr<JsepTransceiver> video(
+      new JsepTransceiver(SdpMediaSection::kVideo, mUuidGen));
   video->mSendTrack.UpdateStreamIds(
       std::vector<std::string>(1, "offerer_stream"));
   mSessionOff->AddTransceiver(video);
@@ -3428,12 +3415,14 @@ TEST_F(JsepSessionTest, ValidateOfferedAudioCodecParams) {
   types.push_back(SdpMediaSection::kAudio);
   types.push_back(SdpMediaSection::kVideo);
 
-  RefPtr<JsepTransceiver> audio(new JsepTransceiver(SdpMediaSection::kAudio));
+  RefPtr<JsepTransceiver> audio(
+      new JsepTransceiver(SdpMediaSection::kAudio, mUuidGen));
   audio->mSendTrack.UpdateStreamIds(
       std::vector<std::string>(1, "offerer_stream"));
   mSessionOff->AddTransceiver(audio);
 
-  RefPtr<JsepTransceiver> video(new JsepTransceiver(SdpMediaSection::kVideo));
+  RefPtr<JsepTransceiver> video(
+      new JsepTransceiver(SdpMediaSection::kVideo, mUuidGen));
   video->mSendTrack.UpdateStreamIds(
       std::vector<std::string>(1, "offerer_stream"));
   mSessionOff->AddTransceiver(video);
@@ -5106,8 +5095,7 @@ TEST_P(JsepSessionTest, TestRejectOfferRollback) {
   ASSERT_FALSE(
       mSessionAns->SetRemoteDescription(kJsepSdpRollback, "").mError.isSome());
   ASSERT_EQ(kJsepStateStable, mSessionAns->GetState());
-  for (const auto& [id, transceiver] : mSessionAns->GetTransceivers()) {
+  for (const auto& transceiver : mSessionAns->GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     ASSERT_EQ(0U, transceiver->mRecvTrack.GetStreamIds().size());
   }
 
@@ -5160,8 +5148,7 @@ TEST_P(JsepSessionTest, TestInvalidRollback) {
 
 size_t GetActiveTransportCount(const JsepSession& session) {
   size_t activeTransportCount = 0;
-  for (const auto& [id, transceiver] : session.GetTransceivers()) {
+  for (const auto& transceiver : session.GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (!transceiver->HasBundleLevel() ||
         (transceiver->BundleLevel() == transceiver->GetLevel())) {
       activeTransportCount += transceiver->mTransport.mComponents;
@@ -5225,8 +5212,7 @@ TEST_P(JsepSessionTest, TestMaxBundle) {
   }
 
   SetLocalOffer(offer);
-  for (const auto& [id, transceiver] : mSessionOff->GetTransceivers()) {
+  for (const auto& transceiver : mSessionOff->GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (transceiver->GetLevel() == 0) {
       // We do not set the bundle-level in have-local-offer unless the
       // m-section is bundle-only.
@@ -6663,7 +6649,7 @@ TEST_F(JsepSessionTest, NoAddTrackMagicReplaceTrack) {
   ASSERT_EQ(2U, mSessionAns->GetTransceivers().size());
   AddTracks(*mSessionOff, "audio");
   mSessionAns->AddTransceiver(
-      new JsepTransceiver(SdpMediaSection::MediaType::kAudio));
+      new JsepTransceiver(SdpMediaSection::MediaType::kAudio, mUuidGen));
 
   mSessionAns->GetTransceivers()[2]->mSendTrack.UpdateStreamIds({"newstream"});
 
@@ -6710,7 +6696,7 @@ TEST_F(JsepSessionTest, AddTrackMakesTransceiverMagical) {
   ASSERT_EQ(2U, mSessionAns->GetTransceivers().size());
   AddTracks(*mSessionOff, "audio");
   mSessionAns->AddTransceiver(
-      new JsepTransceiver(SdpMediaSection::MediaType::kAudio));
+      new JsepTransceiver(SdpMediaSection::MediaType::kAudio, mUuidGen));
 
   ASSERT_EQ(3U, mSessionAns->GetTransceivers().size());
   ASSERT_EQ(0U, mSessionAns->GetTransceivers()[0]->GetLevel());
@@ -6810,7 +6796,7 @@ TEST_F(JsepSessionTest, ComplicatedRemoteRollback) {
       SdpDirectionAttribute::Direction::kRecvonly;
 
   // We do nothing with the second audio transceiver; when we rollback, it will
-  // disappear entirely.
+  // be marked as removed.
 
   // This will not cause the third audio transceiver to stick around; having a
   // track is _not_ enough to preserve it. It must have addTrack "magic"!
@@ -6819,15 +6805,14 @@ TEST_F(JsepSessionTest, ComplicatedRemoteRollback) {
   // Create a fourth audio transceiver. Rollback will leave it alone, since we
   // created it.
   mSessionAns->AddTransceiver(
-      new JsepTransceiver(SdpMediaSection::MediaType::kAudio,
+      new JsepTransceiver(SdpMediaSection::MediaType::kAudio, mUuidGen,
                           SdpDirectionAttribute::Direction::kRecvonly));
 
   ASSERT_FALSE(
       mSessionAns->SetRemoteDescription(kJsepSdpRollback, "").mError.isSome());
 
-  // Three recvonly for audio, one sendrecv for video, and one (unmapped) for
+  // Two of these (3 and 4) will be marked removed, if this all worked
-  // the second video track.
+  ASSERT_EQ(6U, mSessionAns->GetTransceivers().size());
-  ASSERT_EQ(4U, mSessionAns->GetTransceivers().size());
 
   // First video transceiver
   ASSERT_FALSE(mSessionAns->GetTransceivers()[0]->HasLevel());
@@ -6835,6 +6820,7 @@ TEST_F(JsepSessionTest, ComplicatedRemoteRollback) {
   ASSERT_FALSE(mSessionAns->GetTransceivers()[0]->IsAssociated());
   ASSERT_TRUE(mSessionAns->GetTransceivers()[0]->HasAddTrackMagic());
   ASSERT_FALSE(IsNull(mSessionAns->GetTransceivers()[0]->mSendTrack));
+  ASSERT_FALSE(mSessionAns->GetTransceivers()[0]->IsRemoved());
 
   // Second video transceiver
   ASSERT_FALSE(mSessionAns->GetTransceivers()[1]->HasLevel());
@@ -6842,6 +6828,7 @@ TEST_F(JsepSessionTest, ComplicatedRemoteRollback) {
   ASSERT_FALSE(mSessionAns->GetTransceivers()[1]->IsAssociated());
   ASSERT_TRUE(mSessionAns->GetTransceivers()[1]->HasAddTrackMagic());
   ASSERT_FALSE(IsNull(mSessionAns->GetTransceivers()[1]->mSendTrack));
+  ASSERT_FALSE(mSessionAns->GetTransceivers()[1]->IsRemoved());
 
   // First audio transceiver, kept because AddTrack touched it, even though we
   // removed the send track after.
@@ -6850,10 +6837,23 @@ TEST_F(JsepSessionTest, ComplicatedRemoteRollback) {
   ASSERT_FALSE(mSessionAns->GetTransceivers()[2]->IsAssociated());
   ASSERT_TRUE(mSessionAns->GetTransceivers()[2]->HasAddTrackMagic());
   ASSERT_TRUE(IsNull(mSessionAns->GetTransceivers()[2]->mSendTrack));
+  ASSERT_FALSE(mSessionAns->GetTransceivers()[2]->IsRemoved());
 
   // Second audio transceiver should be gone.
+  ASSERT_FALSE(mSessionAns->GetTransceivers()[3]->HasLevel());
+  ASSERT_TRUE(mSessionAns->GetTransceivers()[3]->IsStopped());
+  ASSERT_FALSE(mSessionAns->GetTransceivers()[3]->IsAssociated());
+  ASSERT_FALSE(mSessionAns->GetTransceivers()[3]->HasAddTrackMagic());
+  ASSERT_TRUE(IsNull(mSessionAns->GetTransceivers()[3]->mSendTrack));
+  ASSERT_TRUE(mSessionAns->GetTransceivers()[3]->IsRemoved());
 
   // Third audio transceiver should also be gone.
+  ASSERT_FALSE(mSessionAns->GetTransceivers()[4]->HasLevel());
+  ASSERT_TRUE(mSessionAns->GetTransceivers()[4]->IsStopped());
+  ASSERT_FALSE(mSessionAns->GetTransceivers()[4]->IsAssociated());
+  ASSERT_FALSE(mSessionAns->GetTransceivers()[4]->HasAddTrackMagic());
+  ASSERT_FALSE(IsNull(mSessionAns->GetTransceivers()[4]->mSendTrack));
+  ASSERT_TRUE(mSessionAns->GetTransceivers()[4]->IsRemoved());
 
   // Fourth audio transceiver, created after SetRemote
   ASSERT_FALSE(mSessionAns->GetTransceivers()[5]->HasLevel());
@@ -7126,7 +7126,7 @@ TEST_F(JsepSessionTest, TestOneWayRtx) {
 
 TEST_F(JsepSessionTest, TestRtxNoSsrcGroup) {
   mSessionOff->AddTransceiver(new JsepTransceiver(
-      SdpMediaSection::kVideo, SdpDirectionAttribute::kRecvonly));
+      SdpMediaSection::kVideo, mUuidGen, SdpDirectionAttribute::kRecvonly));
 
   OfferAnswer(CHECK_SUCCESS);
 
@@ -7140,7 +7140,7 @@ TEST_F(JsepSessionTest, TestRtxNoSsrcGroup) {
 
 TEST_F(JsepSessionTest, TestRtxSsrcGroupOnlyOffered) {
   mSessionOff->AddTransceiver(new JsepTransceiver(
-      SdpMediaSection::kVideo, SdpDirectionAttribute::kSendonly));
+      SdpMediaSection::kVideo, mUuidGen, SdpDirectionAttribute::kSendonly));
 
   OfferAnswer(CHECK_SUCCESS);
 
@@ -7166,8 +7166,7 @@ TEST_F(JsepSessionTest, TestOfferRtxNoMsid) {
   AddTracks(*mSessionOff, "video");
 
   std::vector<std::string> streamIds;
-  for (const auto& [id, transceiver] : mSessionOff->GetTransceivers()) {
+  for (const auto& transceiver : mSessionOff->GetTransceivers()) {
-    (void)id;  // Lame, but no better way to do this right now.
     if (!IsNull(transceiver->mSendTrack)) {
       transceiver->mSendTrack.UpdateStreamIds(streamIds);
     }