[flimflam] Don't write back services when they are already dead.

BUG=chromium-os:27751
TEST=Policy-configured VPN networks should actually go away when removed from policy.

Change-Id: I2c8bd97906c28207cda5959fbd2ce3706e54e4aa
Reviewed-on: https://gerrit.chromium.org/gerrit/18153
Tested-by: Mattias Nissler <mnissler@chromium.org>
Reviewed-by: Sam Leffler <sleffler@chromium.org>
Commit-Ready: Mattias Nissler <mnissler@chromium.org>
1 file changed