Make GetEncryptionKey thread-safe

Make GetEncryptionKey thread-safe

The current implementation of |GetEncryptionKey()| is thread-unsafe, resulting
in a flaky unit test. This change fixes this issue by making the lock a
|LazyInstance| instead of static.

BUG=656926
R=cfroussios@chromium.org

Committed: https://crrev.com/e9fc2e0c783274f4edd3adb175edf39d2ea8327b
Cr-Commit-Position: refs/heads/master@{#429547}

[cfroussios, 2016-11-03 09:02:26]

lgtm

[jdoerrie, 2016-11-03 09:04:49]

The CQ bit was checked by jdoerrie@chromium.org

[commit-bot: I haz the power, 2016-11-03 09:04:58]

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, 2016-11-03 11:05:27]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-11-03 11:05:28]

Try jobs failed on following builders:
  linux_chromium_asan_rel_ng on master.tryserver.chromium.linux (JOB_TIMED_OUT,
no build URL)

[jdoerrie, 2016-11-03 11:38:19]

The CQ bit was checked by jdoerrie@chromium.org

[commit-bot: I haz the power, 2016-11-03 11:38:40]

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, 2016-11-03 12:49:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-03 12:54:18]

Description was changed from

==========
Make GetEncryptionKey thread-safe

The current implementation of |GetEncryptionKey()| is thread-unsafe, resulting
in a flaky unit test. This change fixes this issue by making the lock a
|LazyInstance| instead of static.

BUG=656926
R=cfroussios@chromium.org
==========

to

==========
Make GetEncryptionKey thread-safe

The current implementation of |GetEncryptionKey()| is thread-unsafe, resulting
in a flaky unit test. This change fixes this issue by making the lock a
|LazyInstance| instead of static.

BUG=656926
R=cfroussios@chromium.org

Committed: https://crrev.com/e9fc2e0c783274f4edd3adb175edf39d2ea8327b
Cr-Commit-Position: refs/heads/master@{#429547}
==========

[commit-bot: I haz the power, 2016-11-03 12:54:19]

Patchset 1 (id:??) landed as
https://crrev.com/e9fc2e0c783274f4edd3adb175edf39d2ea8327b
Cr-Commit-Position: refs/heads/master@{#429547}