Port device_cloud_policy_manager_chromeos_unittest to GetSafeWeakWrapper

When using GetSafeWeakWrapper, Detach() is called automatically, so
tests don't need to call it themselves.

Bug: 924960
Change-Id: Ie196ff8de72ae025ed6253269d46fb270ffae0c8
Reviewed-on: https://chromium-review.googlesource.com/c/1475437
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Commit-Queue: Lowell Manners <lowell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#633050}
1 file changed