This will speed up key frame encoding (together with libaom changes) 3x-4x times with ~13% BDRate loss on key frames only Bug: None Change-Id: I24332f4f7285811cdc6619ba29844fe564cae95e Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/212040 Reviewed-by: Marco Paniconi <marpan@webrtc.org> Commit-Queue: Fyodor Kyslov <kyslov@google.com> Cr-Commit-Position: refs/heads/master@{#33468}