Move IsSyncConfirmationNeeded out of ProfileSyncService

...and into sync_ui_util, where it belongs.
This means that some ProfileSyncService unit tests can't verify it
anymore because it now lives in chrome/browser, but that seems okay
(it's still tested in sync_ui_util_unittest.cc).

Also use this chance to rename it to ShouldShowSyncConfirmation, which
better describes what it means.

Bug: 884159
Change-Id: I14149544d353491ace0590a530e65d0d7687d09f
Reviewed-on: https://chromium-review.googlesource.com/c/1356705
Reviewed-by: Florian Uunk <feuunk@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613095}
8 files changed