This is a step toward simplifying the VideoCodec struct and removing the
targetBitrate. The hard-coded values now reside in
SimulcastRateAllocator.
A follow-up will do away with the field altogether.
Bug: webrtc:9504
Change-Id: I74d483682309d363048fbbbd31e0607d7242f504
Reviewed-on: https://webrtc-review.googlesource.com/87424
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23876}
5e898d612e