The flag is always on and support for turning it off is broken with
conservative barriers.

Bug: 
Change-Id: I1ff548f95d220bf0fcb6df7a1bf5f8a342163696
Reviewed-on: https://chromium-review.googlesource.com/624494
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47482}