Use 4 threads for 360p and above. Use tile rows for VGA and 4 threads. Use speed 8 for 360p. Change min max qp scaling threshold. Bug: None Change-Id: Ib7a5b7e539d26d9fa60aa2c4a75eb6f4b19f7dea Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/208340 Commit-Queue: Jerome Jiang <jianj@google.com> Commit-Queue: Fyodor Kyslov <kyslov@google.com> Reviewed-by: Marco Paniconi <marpan@webrtc.org> Cr-Commit-Position: refs/heads/master@{#33320}