Sample region under secondary home handle

Also fixed a bug where home handle drawing
was not taking into display cutout insets.
The approach now is to look at the location
of the view and derive the inset from there,
bug outstand to get it from window insets.
b/158219739

Bug: 150250451
Test: Quickswitched between apps that
had different shade background from
apps default foreground rotation navbar
location. Light/Dark transition worked as
expected.

Change-Id: I40e41082af413a98157d274e790c36ede62847d1