TBR=yangguo@chromium.org

Change-Id: Iadeb5828daf4db341c58534ff2b23141f241dfb9
Reviewed-on: https://chromium-review.googlesource.com/1184841
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55314}