Create button which ignores clicks when window is partially obscured

Currently there is a protection to prevent clicks which go through an
overlay, but the overlay might be covering sensitive information rather
than the button. We now prevent clicks if there is any overlay over any part
of the window.

Test: Manual
Test: atest PermissionTapjackingTest
Bug: 175190844

Change-Id: Ie0238aede5fb1d781e71c3c6f30b63dd02a1eb2c
2 files changed