Fixed that touches where incorrectly consumed when fullscreen

The fake window that was added when View.SYSTEM_UI_FULL_SCREEN was
set consumed all touches, even those going to the SystemUI and not
just those of windows below. The input consumer is now correctly
positioned in the window order to only capture the right touches.
Clicks to the volume panel and the heads up now correctly go to the
right place instead of just unhiding the SystemUI bars.

Bug: 21089476
Change-Id: Ib53dfc0b33b70084ca607d0f044db30b6e6c91d6