This was a mistake from change 273800 in that it could try to send
packets if there wasn't a connection established - when tcb_ was
nullptr.
Bug: chromium:1360268
Change-Id: Idd4406071dbd8ac89303aef61840895505417569
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/274405
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Auto-Submit: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38031}