Get autolock delay from policy

This commit gets the autolock delay time for ChromeOS
from policies and send the information to chrome.idle.getAutoLockDelay.

BUG=chromium:907751

Change-Id: I33006f6498621c7d46a49ee67814f5266408838a
Reviewed-on: https://chromium-review.googlesource.com/c/1382443
Commit-Queue: Andreea-Elena Costinas <acostinas@google.com>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Reviewed-by: Lutz Justen <ljusten@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622399}
18 files changed