Offset task coordinates from activity layer crops

Current logic uses the boudns of the parent of the activity, but it only
offsets the position of the activity layer. It should also offset the
position of the parent layer.

Bug: 232459537
Test: The final crop state is correct after launching an activity if the
task isn't at the top-left corner.

Change-Id: I3b5d48d1410533a40842870a0164c34c612cc886