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This version calls `RandomValue` less often, which exercises atomics less, so
should be faster.

Thanks to vtsyrklevich for the idea and technique.

Bug: 984742, 1006176, 1005678, 1005677, 1005248, 1005068, 1005066, 1006178, 1006071
Change-Id: I6a60e5a9b18588f56fff5b38a58c511f6ac0c850
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1817188
Commit-Queue: Chris Palmer <palmer@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704306}