Multithreading is more effective. Change-Id: Ic850de4ee6affe3c0f623deb0318f991675c4351 Bug: None Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/208300 Reviewed-by: Marco Paniconi <marpan@webrtc.org> Commit-Queue: Jerome Jiang <jianj@google.com> Cr-Commit-Position: refs/heads/master@{#33306}