Required for the rest of Chromium to compile with the warning enabled.

Bug: chromium:766891
Change-Id: Ie319df01599434011dc953532a30ad68d6a7c9a3
Reviewed-on: https://chromium-review.googlesource.com/c/1390659
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>