Seems like a feature request, tagging accordingly.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7463f4b9a61a23de4ee9ad3c837e7cfcd38ba2f7

commit 7463f4b9a61a23de4ee9ad3c837e7cfcd38ba2f7
Author: Lutz Justen <ljusten@chromium.org>
Date: Wed Sep 20 15:32:10 2017

Create a JSON schema to ADMX converter

Adds a script that generates an ADMX template from an extension
schema.json file. The ADMX template can be used to set policy for
that extension in Active Directory.

The goal is to support extension policy for Active Directory managed
Chromebooks. Historically, extension policy for Chromebooks is set in
CPanel (the Google Cloud management console) by pasting JSON code.
Therefore, ADMX templates are usually not available for Chrome OS-
only policies like "Certificate Enrollment for Chrome OS". This CL
makes it easy to generate such a template.

Supports bool, int, string and string list type policies. Enums and
minimum/maximum values are not supported yet. Translation is not
supported as well, only one language. All this should be easy to add,
though.

BUG= chromium:756356 
TEST=Generated ADMX for Managed Bookmarks extension, see example near
      top of the file. Also tested with LegacyBrowserSupport schema,
      result looks very similar to original ADMX/ADML.

Change-Id: Ie2d18a74dffb9f896f8a0085e0c97d5a483fea55
Reviewed-on: https://chromium-review.googlesource.com/667017
Commit-Queue: Lutz Justen <ljusten@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#503152}
[add] https://crrev.com/7463f4b9a61a23de4ee9ad3c837e7cfcd38ba2f7/components/policy/tools/generate_extension_admx.py

Verified the following in this bug:

as per provided example, using the managed_bookmarks.zip extension, generate_extension_admx.py script generates ADMX/ADML templates:

managed_bookmarks.admx
managed_bookmarks.adml

Based on this, changing the status to "Verified", however those two templates need to be tested in Active Directory.