GitLab

Document some intent of atomic operations with memory order
directives and make some comments more correct.

Bug: 1034046
Change-Id: Ice1968a2b655e2dd5e0dbdcf0a7fd12d2f8be166
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2079198Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Oliver Li <olivierli@google.com>
Cr-Commit-Position: refs/heads/master@{#748790}