Protect VPN dialogs against overlay.

Bug: 130568701
Test: manual. After this, can't display on top of it
Change-Id: Ib032f800edb0416cc15f01a34954340d0d0ffa78
Merged-In: Ib032f800edb0416cc15f01a34954340d0d0ffa78
(cherry picked from commit 4e80dc2861614d25a1f957f50040a8cf04812d11)
(cherry picked from commit 016c72c8abfbae08eda269afb8923e8fc8a4ce44)
2 files changed