Add a new AssociationState DEPROVISIONED for cloud policy.

This adds a new enum value to Policy.AssociationState, indicating that
the server side dropped the client from management. The association
state is now also surfaced in the Status line in about:policy.

BUG=chromium:329834

Review URL: https://codereview.chromium.org/117253002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242099 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242099