Hold allocator lock while fetching 'used' count.

Hold allocator lock while fetching 'used' count.

Also: Use acquire/release for ready_ as suggested in
post-commit comment:
https://codereview.chromium.org/2249683003/

BUG=655953
Committed: https://crrev.com/1164a42fe0c7f7646822e826597dd5299530f4e2
Cr-Commit-Position: refs/heads/master@{#425395}

[bcwhite, 2016-10-14 17:27:53]

bcwhite@chromium.org changed reviewers:
+ manzagop@chromium.org

[manzagop (departed), 2016-10-14 18:08:21]

lgtm

[bcwhite, 2016-10-14 18:17:40]

The CQ bit was checked by bcwhite@chromium.org

[commit-bot: I haz the power, 2016-10-14 18:18:30]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-14 18:34:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-10-14 18:36:00]

Description was changed from

==========
Hold allocator lock while fetching 'used' count.

Also: Use acquire/release for ready_ as suggested in
post-commit comment:
https://codereview.chromium.org/2249683003/

BUG=655953
==========

to

==========
Hold allocator lock while fetching 'used' count.

Also: Use acquire/release for ready_ as suggested in
post-commit comment:
https://codereview.chromium.org/2249683003/

BUG=655953

Committed: https://crrev.com/1164a42fe0c7f7646822e826597dd5299530f4e2
Cr-Commit-Position: refs/heads/master@{#425395}
==========

[commit-bot: I haz the power, 2016-10-14 18:36:01]

Patchset 1 (id:??) landed as
https://crrev.com/1164a42fe0c7f7646822e826597dd5299530f4e2
Cr-Commit-Position: refs/heads/master@{#425395}