Remove DtlsHandShakeError and replace it with a Function Pointer.

- Remove the last sigslot from JsepTransportController.
- Tested the potential test failure on chromium blink test by importing
  this CL to chromium source.

Bug: webrtc:11943
Change-Id: I107d05606350aff655ca73a5cb640dff1a7036ee
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/202741
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33085}

pc/jsep_transport_controller.cc

@@ -87,6 +87,7 @@ JsepTransportController::JsepTransportController(
   RTC_DCHECK(config_.transport_observer);
   RTC_DCHECK(config_.rtcp_handler);
   RTC_DCHECK(config_.ice_transport_factory);
+  RTC_DCHECK(config_.on_dtls_handshake_error_);
 }
 
 JsepTransportController::~JsepTransportController() {
@@ -1411,7 +1412,7 @@ void JsepTransportController::OnRtcpPacketReceived_n(
 
 void JsepTransportController::OnDtlsHandshakeError(
     rtc::SSLHandshakeError error) {
-  SignalDtlsHandshakeError(error);
+  config_.on_dtls_handshake_error_(error);
 }
 
 }  // namespace webrtc

pc/jsep_transport_controller.h

@@ -103,6 +103,7 @@ class JsepTransportController : public sigslot::has_slots<> {
 
     // Factory for SCTP transports.
     SctpTransportFactoryInterface* sctp_factory = nullptr;
+    std::function<void(const rtc::SSLHandshakeError)> on_dtls_handshake_error_;
   };
 
   // The ICE related events are signaled on the |signaling_thread|.
@@ -192,8 +193,6 @@ class JsepTransportController : public sigslot::has_slots<> {
   // and deletes unused transports, but doesn't consider anything more complex.
   void RollbackTransports();
 
-  sigslot::signal1<rtc::SSLHandshakeError> SignalDtlsHandshakeError;
-
   // F: void(const std::string&, const std::vector<cricket::Candidate>&)
   template <typename F>
   void SubscribeIceCandidateGathered(F&& callback) {

pc/jsep_transport_controller_unittest.cc

@@ -82,6 +82,7 @@ class JsepTransportControllerTest : public JsepTransportController::Observer,
                              int64_t packet_time_us) { RTC_NOTREACHED(); };
     config.ice_transport_factory = fake_ice_transport_factory_.get();
     config.dtls_transport_factory = fake_dtls_transport_factory_.get();
+    config.on_dtls_handshake_error_ = [](rtc::SSLHandshakeError s) {};
     transport_controller_ = std::make_unique<JsepTransportController>(
         signaling_thread, network_thread, port_allocator,
         nullptr /* async_resolver_factory */, config);

pc/peer_connection.cc

@@ -453,7 +453,8 @@ PeerConnection::PeerConnection(
       call_(std::move(call)),
       call_ptr_(call_.get()),
       data_channel_controller_(this),
-      message_handler_(signaling_thread()) {}
+      message_handler_(signaling_thread()),
+      weak_factory_(this) {}
 
 PeerConnection::~PeerConnection() {
   TRACE_EVENT0("webrtc", "PeerConnection::~PeerConnection");
@@ -602,18 +603,22 @@ RTCError PeerConnection::Initialize(
   }
 
   config.ice_transport_factory = ice_transport_factory_.get();
+  config.on_dtls_handshake_error_ =
+      [weak_ptr = weak_factory_.GetWeakPtr()](rtc::SSLHandshakeError s) {
+        if (weak_ptr) {
+          weak_ptr->OnTransportControllerDtlsHandshakeError(s);
+        }
+      };
 
   transport_controller_.reset(new JsepTransportController(
       signaling_thread(), network_thread(), port_allocator_.get(),
       async_resolver_factory_.get(), config));
 
-  transport_controller_->SignalDtlsHandshakeError.connect(
-      this, &PeerConnection::OnTransportControllerDtlsHandshakeError);
-
-  // Following RTC_DCHECKs are added by looking at the caller thread.
+  // The following RTC_DCHECKs are added by looking at the caller thread.
   // If this is incorrect there might not be test failures
   // due to lack of unit tests which trigger these scenarios.
   // TODO(bugs.webrtc.org/12160): Remove above comments.
+  // callbacks for signaling_thread.
   transport_controller_->SubscribeIceConnectionState(
       [this](cricket::IceConnectionState s) {
         RTC_DCHECK_RUN_ON(signaling_thread());

pc/peer_connection.h

@@ -692,6 +692,8 @@ class PeerConnection : public PeerConnectionInternal,
   // Administration of senders, receivers and transceivers
   // Accessed on both signaling and network thread. Const after Initialize().
   std::unique_ptr<RtpTransmissionManager> rtp_manager_;
+
+  rtc::WeakPtrFactory<PeerConnection> weak_factory_;
 };
 
 }  // namespace webrtc