Report drag success/fail in the DRAG_ENDED message

DragEvent.getResult() returns 'true' if the drop was ultimately accepted;
false otherwise.  The validity of this datum is only guaranteed when the
DragEvent's action verb is ACTION_DRAG_ENDED.

Also fixes the drag-start timeout handling (though the offending app is
not yet officially declared ANR).

Implements bug 3097807

Change-Id: I6908ac628c72ff7d6193d87060d769a559a78d0e
6 files changed