Forward events to ListPopupWindow, highlight touched items

Moves most of the drag-to-open behavior into ListPopupWindow's
particular implementation of ListView. Uses hidden View API for
forwarding events between different windows.

Overflow menu opens on first touch, closes on touch end outside
the overflow button. Clicks that occur during drag-to-open mode
result in alpha animation of the selector drawable.

BUG: 9437139
Change-Id: I70f540555a03450638a27880b3ae3b031ca6e2ed