GitLab

When we have satisfied the allocation with a new OS page, we can skip the
`memset`.

Bug: 864462
Change-Id: Ib13539a83a931dbad3e588001aa248ff994d3900
Reviewed-on: https://chromium-review.googlesource.com/1213957
Commit-Queue: Chris Palmer <palmer@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595218}