This does the bulk of the remaining refactoring, except timers since they are an even bigger part - but more isolated. Bug: webrtc:15593 Change-Id: I7afa349e2119be7592797ee6b3b198e6de4f697a Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/326160 Commit-Queue: Victor Boivie <boivie@webrtc.org> Reviewed-by: Florent Castelli <orphis@webrtc.org> Cr-Commit-Position: refs/heads/main@{#41090}