GitLab

Like base::bits::Align(), but rounds down instead. Replace duplicate
implementations.

Change-Id: I7ad74d021feba26a34f2c80bc025e9ab9fe6660a
Reviewed-on: https://chromium-review.googlesource.com/c/1369047Reviewed-by: vmpstr <vmpstr@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Albert J. Wong <ajwong@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615610}