The draft CL crrev.com/c/963648 duplicates mount-encrypted logs in syslog to keep over reboots.
In addition, it would be great to directly save mount-encrypted logs in stateful instead of /tmp to cover the cases when the device reboots as a result of mount-encrypted error before getting to the stage where it has /var/log and syslogd running and can copy the log from /tmp to there. These cases will be added with special TPM comm error handling in mount-encrypted.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/6c13f1527429b976b8d114bea9760374751089eb

commit 6c13f1527429b976b8d114bea9760374751089eb
Author: Andrey Pronin <apronin@chromium.org>
Date: Sat Apr 14 04:37:55 2018

cryptohome: preserve mount-encrypted logs over reboots

In addition to creating a new /var/log/mount-encrypted.log for each
boot, dump its contents into syslog, so that it's possible to see
mount-encrypted logs from previous boots in /var/log/messages.

Don't get rid of /var/log/mount-encrypted.log to always have it in
feedback reports even if system messages from boot time are rotated
to /var/log/messages.N files not included there.

BUG= chromium:822134 
TEST=check that mount-encrypted.log is dumped to syslog

Change-Id: Id21d41fbec1cac94a7c729836017583823a5a4c3
Reviewed-on: https://chromium-review.googlesource.com/963648
Commit-Ready: Andrey Pronin <apronin@chromium.org>
Tested-by: Andrey Pronin <apronin@chromium.org>
Reviewed-by: Andrey Pronin <apronin@chromium.org>

[modify] https://crrev.com/6c13f1527429b976b8d114bea9760374751089eb/cryptohome/init/mount-encrypted.conf