This change allows work to be done in parallel for lower level implementation and wiring/exposing multiple simulcast layer's encoding parameters at the api interface.
Bug: webrtc:8653
Change-Id: I89c9a6af0786134771d28526056759bd63213a0a
Reviewed-on: https://webrtc-review.googlesource.com/32902
Reviewed-by: Peter Thatcher <pthatcher@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Seth Hampson <shampson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21375}