Make ProfileSyncService::IsSyncConfirmationNeeded non-virtual

...and update the tests that depended on overriding it.

Bug: 884159
Change-Id: Iac892550720e19ee5d334f0598413b7e225b8338
Reviewed-on: https://chromium-review.googlesource.com/c/1356704
Reviewed-by: Florian Uunk <feuunk@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612635}
3 files changed