Reverting ag/1288123

- Reverts the change to draw the drop targets opposite of the nav bar
- Fixes the issue with the drop divider being occluded by the nav bar
  when the phone is in landscape orientation.  Instead, expand the 
  drag overlay to include the nav bar space.

Bug: 30548794
Change-Id: I70ed3513547e101e49c8eba114a153c5a1f36bee