The send queue is responsible for generating lifecycle events for all
messages that are still in the queue. Because, if they are still in the
queue, that means that the last fragment of the message hasn't been sent
yet (because then it would have been in the retransmission queue
instead). And if the last fragment hasn't been sent, the send queue is
responsible for generating the
`OnLifecycleMessageExpired(/*maybe_sent=*/false)` event.
Bug: webrtc:5696
Change-Id: Icd5956d6aa0f392cae54f2a05bd20728d9f7f0a6
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/264144
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37419}