Support WebRTC-DataChannelMessageInterleaving

If the field trial WebRTC-DataChannelMessageInterleaving is set, message
interleaving in SCTP (RFC8260) will be enabled in dcSCTP.

Bug: webrtc:41481008
Change-Id: I989b9ca554439ab0afd71f04d14a5cb5444b3361
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/354480
Reviewed-by: Florent Castelli <orphis@webrtc.org>
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42469}
diff --git a/media/sctp/dcsctp_transport.cc b/media/sctp/dcsctp_transport.cc
index 99ecc94..3d54b7d 100644
--- a/media/sctp/dcsctp_transport.cc
+++ b/media/sctp/dcsctp_transport.cc
@@ -197,6 +197,8 @@
         DataChannelInterface::MaxSendQueueSize();
     // This is just set to avoid denial-of-service. Practically unlimited.
     options.max_send_buffer_size = std::numeric_limits<size_t>::max();
+    options.enable_message_interleaving =
+        env_.field_trials().IsEnabled("WebRTC-DataChannelMessageInterleaving");
 
     std::unique_ptr<dcsctp::PacketObserver> packet_observer;
     if (RTC_LOG_CHECK_LEVEL(LS_VERBOSE)) {