Test post enrollment policy fetch for Machine-level-user-cloud-policy.

Add three browser tests for fetching machine level user cloud policy
after the enrollment.
  1) Start Chrome with a valid DM token but no policy cache. Chrome will
  load the policy from the DM server.
  2) Start Chrome with an invalid DM token. Chrome will hit the DM server and
  get an error. There should be no more cloud policy applied.
  3) Start Chrome without DM token. Chrome will register itself and fetch
  policy after it.

Also update local policy server for the tests:
  1) Create temp |server_data_dir_| when init with config file so that
  additional arguments can be applied.
  2) Add two new new policy types.
  3) RegisterBrowser now stores the DM token for policy fetch later.

Change-Id: I88d82edb4a794b8c8628b78054084da68d1b6a31
Reviewed-on: https://chromium-review.googlesource.com/c/1465142
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Commit-Queue: Owen Min <zmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631839}
3 files changed