in marking worklist.

Bug: chromium:769173
Change-Id: I4b3ce27d37bec19ec5cc342b4d26a2a45af34b5f
Reviewed-on: https://chromium-review.googlesource.com/691728Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48224}