This CL adds a field trial to enable the BBR congestion control method.
Since BBR is only implemented to handle per packet feedback,
SendSideCongestionController is modified to recreate network controllers
when the packet feedback availability changes and the BBR experiment is
enabled.
This also means that the periodic task used for process updates in the
network controllers has to recreated.
Bug: webrtc:8415
Change-Id: Ia24f7ad35336d2cc7a02bb3a445f1a84b8643475
Reviewed-on: https://webrtc-review.googlesource.com/61520
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22791}
