Changing the currently embedded scheduler that was implemented using a
revolving pointer, to the parameterized stream scheduler that is
implemented using a "virtual finish time" approach.
Also renamed StreamCallback to StreamProducer, per review comments.
Bug: webrtc:5696
Change-Id: I7719678776ddbe05b688ada1b52887e5ca2fb206
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/262160
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37170}
d729d12454