Expand ownership of incognito whitelist to pref_service_syncable_util.cc

e.g. for CLs like https://chromium-review.googlesource.com/c/chromium/src/+/1142503

R=rhalavati@chromium.org

Bug: 861722
Change-Id: I9c7d48e6c73dae3af13d48e32d224600f2f10aa2
Reviewed-on: https://chromium-review.googlesource.com/1156476
Reviewed-by: Ramin Halavati <rhalavati@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579405}
1 file changed