BUG=chromium:801097

Change-Id: Ie631822a668b55b0f0790b719e7d8cdde78d95c6
Reviewed-on: https://chromium-review.googlesource.com/861882
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50544}