If the listener's onDrag(view, event) returns 'false', the view's own
onDragEvent() will be called. If the listener returns 'true', it
consumes the event (and declares that it will handle the rest of the
drag event sequence, in the case of DRAG_STARTED actions).
Change-Id: I01aff0e4f59f71e55f5eea1049905c80714f0607
32affef4f8