FTR, I did this as it was very verbose in Google's policy management tool otherwise (IIRC).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0d9428bb6b7d6a77e1d68f26d5dad81b224148d5

commit 0d9428bb6b7d6a77e1d68f26d5dad81b224148d5
Author: aberent <aberent@chromium.org>
Date: Tue Nov 29 10:31:10 2016

[Android app restrictions] Hide unused and improve descriptions.

Remove future and deprecated policies from app_restrictions.xml and
restriction_values.xml, hence making them invisible to Android policy
managers. Also include all lines of multiline descriptions of policies.

BUG= 616800 
BUG= 616801 

Review-Url: https://codereview.chromium.org/2529383003
Cr-Commit-Position: refs/heads/master@{#434949}

[modify] https://crrev.com/0d9428bb6b7d6a77e1d68f26d5dad81b224148d5/components/policy/tools/generate_policy_source.py
[modify] https://crrev.com/0d9428bb6b7d6a77e1d68f26d5dad81b224148d5/tools/grit/grit/format/policy_templates/writers/android_policy_writer.py
[modify] https://crrev.com/0d9428bb6b7d6a77e1d68f26d5dad81b224148d5/tools/grit/grit/format/policy_templates/writers/android_policy_writer_unittest.py