arc: Don't update install time for apps, installed by PAI or policy.

This to let App Launcher correctly rank app and prevent coming these
apps to the recent list.

TEST=Manually + unit_test
BUG=757639

Change-Id: Ifff93cc7089531d2450d2584baedd8a6002ec353
Reviewed-on: https://chromium-review.googlesource.com/1138748
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Yury Khmel <khmel@google.com>
Cr-Commit-Position: refs/heads/master@{#575730}
7 files changed