The code path it calls is no longer actually used and will be cleaned
up in a follow-up CL.
This prepares for simplifying the transport feedback adapter and moving
it to run on a task queue.
Bug: webrtc:9883
Change-Id: I750398069414ffa782067d021c0a3837049d98eb
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/158621
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29638}