This missing include was also breaking the build on linux.

Change-Id: I55ba5e4df83dc8f5268d7c4afdd92e83add6aca5
Reviewed-on: https://chromium-review.googlesource.com/184376Reviewed-by: Nicolas Capens <nicolascapens@chromium.org>
Commit-Queue: Nicolas Capens <nicolascapens@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>