This is part of moving calls to GetSendRates() to the worker. Change-Id: Ifb93096a863ddf2669237e7f44af296d0e086b20 Bug: webrtc:11581 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/177661 Commit-Queue: Tommi <tommi@webrtc.org> Reviewed-by: Erik Språng <sprang@webrtc.org> Cr-Commit-Position: refs/heads/master@{#31582}