add thread check in DcSctpTransport::OnTransportReadPacket

Bug: None
Change-Id: I1e5e28674617e9ebb322831f95f6f6b88daa7be6
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/245600
Reviewed-by: Victor Boivie <boivie@webrtc.org>
Reviewed-by: Florent Castelli <orphis@webrtc.org>
Commit-Queue: Florent Castelli <orphis@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35679}

media/sctp/dcsctp_transport.cc

@@ -525,6 +525,7 @@ void DcSctpTransport::OnTransportReadPacket(
     size_t length,
     const int64_t& /* packet_time_us */,
     int flags) {
+  RTC_DCHECK_RUN_ON(network_thread_);
   if (flags) {
     // We are only interested in SCTP packets.
     return;