* Make View.onDragEvent() public instead of protected. * No longer @hide View.startDrag() * Properly manage the boundaries of DRAG_STARTED / DRAG_ENDED notifications to windows (and as a result don't send bogus empty DRAG_STARTED events or double-recycle pooled DragEvents) Change-Id: Ib75f5c1417640c82a5b043c555e02d6e6f4b4d9c