This is mainly a refactoring commit, to break out packet sending to a dedicated component. Bug: webrtc:12943 Change-Id: I78f18933776518caf49737d3952bda97f19ef335 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/228565 Reviewed-by: Florent Castelli <orphis@webrtc.org> Commit-Queue: Victor Boivie <boivie@webrtc.org> Cr-Commit-Position: refs/heads/master@{#34772}