Change Identity Service impl to depend only on signin internals

Now that a distinct GN target exists just for the code backing
IdentityManager/Identity Service, change the Identity Service
implementation to depend only on that target. The change worked right
out of the box -- good validation of the initial split.

Bug: 901859
Change-Id: I9b04ef952c34d9e9c0efcf137c55d41c8d616aff
Reviewed-on: https://chromium-review.googlesource.com/c/1323649
Commit-Queue: Colin Blundell <blundell@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606806}
1 file changed