1 files changed, 19 insertions, 15 deletions

diff --git a/third_party/libwebrtc/pc/dtls_transport.cc b/third_party/libwebrtc/pc/dtls_transport.cc
index 15eed9e47b..4888d9f9e7 100644
--- a/third_party/libwebrtc/pc/dtls_transport.cc
+++ b/third_party/libwebrtc/pc/dtls_transport.cc
@@ -41,8 +41,18 @@ DtlsTransport::DtlsTransport(
 }
 
 DtlsTransport::~DtlsTransport() {
+  // TODO(tommi): Due to a reference being held by the RtpSenderBase
+  // implementation, the last reference to the `DtlsTransport` instance can
+  // be released on the signaling thread.
+  // RTC_DCHECK_RUN_ON(owner_thread_);
+
   // We depend on the signaling thread to call Clear() before dropping
   // its last reference to this object.
+
+  // If there are non `owner_thread_` references outstanding, and those
+  // references are the last ones released, we depend on Clear() having been
+  // called from the owner_thread before the last reference is deleted.
+  // `Clear()` is currently called from `JsepTransport::~JsepTransport`.
   RTC_DCHECK(owner_thread_->IsCurrent() || !internal_dtls_transport_);
 }
 
@@ -72,14 +82,8 @@ void DtlsTransport::Clear() {
   RTC_DCHECK(internal());
   bool must_send_event =
       (internal()->dtls_state() != DtlsTransportState::kClosed);
-  // The destructor of cricket::DtlsTransportInternal calls back
-  // into DtlsTransport, so we can't hold the lock while releasing.
-  std::unique_ptr<cricket::DtlsTransportInternal> transport_to_release;
-  {
-    MutexLock lock(&lock_);
-    transport_to_release = std::move(internal_dtls_transport_);
-    ice_transport_->Clear();
-  }
+  internal_dtls_transport_.reset();
+  ice_transport_->Clear();
   UpdateInformation();
   if (observer_ && must_send_event) {
     observer_->OnStateChange(Information());
@@ -100,7 +104,6 @@ void DtlsTransport::OnInternalDtlsState(
 
 void DtlsTransport::UpdateInformation() {
   RTC_DCHECK_RUN_ON(owner_thread_);
-  MutexLock lock(&lock_);
   if (internal_dtls_transport_) {
     if (internal_dtls_transport_->dtls_state() ==
         DtlsTransportState::kConnected) {
@@ -125,23 +128,24 @@ void DtlsTransport::UpdateInformation() {
       success &= internal_dtls_transport_->GetSslCipherSuite(&ssl_cipher_suite);
       success &= internal_dtls_transport_->GetSrtpCryptoSuite(&srtp_cipher);
       if (success) {
-        info_ = DtlsTransportInformation(
+        set_info(DtlsTransportInformation(
             internal_dtls_transport_->dtls_state(), role, tls_version,
             ssl_cipher_suite, srtp_cipher,
-            internal_dtls_transport_->GetRemoteSSLCertChain());
+            internal_dtls_transport_->GetRemoteSSLCertChain()));
       } else {
         RTC_LOG(LS_ERROR) << "DtlsTransport in connected state has incomplete "
                              "TLS information";
-        info_ = DtlsTransportInformation(
+        set_info(DtlsTransportInformation(
             internal_dtls_transport_->dtls_state(), role, absl::nullopt,
             absl::nullopt, absl::nullopt,
-            internal_dtls_transport_->GetRemoteSSLCertChain());
+            internal_dtls_transport_->GetRemoteSSLCertChain()));
       }
     } else {
-      info_ = DtlsTransportInformation(internal_dtls_transport_->dtls_state());
+      set_info(
+          DtlsTransportInformation(internal_dtls_transport_->dtls_state()));
     }
   } else {
-    info_ = DtlsTransportInformation(DtlsTransportState::kClosed);
+    set_info(DtlsTransportInformation(DtlsTransportState::kClosed));
   }
 }