1) Fix several typos and small mistakes which could lead to crashes 2) Adjust bitrates if leading layers are disabled 3) Wire up webrtc quality scaler Bug: webrtc:11319 Change-Id: I16e52bdb1c315d64906288e4f2be55fe698d5ceb Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/177525 Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org> Reviewed-by: Erik Språng <sprang@webrtc.org> Cr-Commit-Position: refs/heads/master@{#31546}