[s13n] Move CloudPolicyManagerTest away from using SigninManager

This CL makes CloudPolicyManagerTest use IdentityManager instead
of SigninManager.

SigninManager is going to be an implementation detail of
IdentityManager.

Bug: 920215
Change-Id: I9f379321fa02133349113c96f60bab5aa27fe7bb
Reviewed-on: https://chromium-review.googlesource.com/c/1411195
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Julie Jeongeun Kim <jkim@igalia.com>
Cr-Commit-Position: refs/heads/master@{#622865}
1 file changed