Use base::size rather than arraysize in testing/.

This is purely a mechanical change; there is no intended behavior change.

BUG=837308
TBR=jbudorick@chromium.org

Change-Id: I65f8cb1557478dff4826ddab93764be0eeaf987d
Reviewed-on: https://chromium-review.googlesource.com/c/1390110
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618836}
1 file changed