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The TLS version has the same performance compared to lock-free version,
and also has the following benefits:
  - simpler code
  - handles multithreaded allocations with higher accuracy

It although has a potential corner case issue when there are lots
or short living threads each allocating small amount of memory.

BUG=803276,812262

Change-Id: Ie868f07b99559d8cc95d134eed6592bffe1f63aa
Reviewed-on: https://chromium-review.googlesource.com/944052
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Primiano Tucci <primiano@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542635}