Oilpan: Fix data races in HeapTest

Fixes data races TSan found in HeapTest

Bug: 831674
Change-Id: Id2d347483a9339d201554862799a4528b542230e
Reviewed-on: https://chromium-review.googlesource.com/1121666
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Keishi Hattori <keishi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571774}
1 file changed