GitLab

When policy is set on server, background and foreground of
FilesApp will listen to changes in pref and hide/show the
"Install with Linux (Beta)" context menu option

Follow up CL to http://crosreview.com/1712667

Bug: 983997, 983998, 988375
Test: compile
Change-Id: I666cb79e48e876cb222a0dead3e6cf96a5a0a28a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1730907Reviewed-by: Joel Hockey <joelhockey@chromium.org>
Commit-Queue: Christopher Gunadi <chrisgunadi@google.com>
Cr-Commit-Position: refs/heads/master@{#683942}