Change approach for windowPositionLostRT

Bug: 29547000

Instead of shifting the window off screen fall
back to the UI-thread calculated values. This fixes
a race issue around tear-down where we stop
drawing long before our window is actually no longer
visible, as well as fixes a funky issue with
PRESERVE_GEOMETRY during first draw.

Change-Id: I792d1966f5aaee1e703295ae79166c723b97a1dc