tree b3bdc0c63c2540f57042c0d09d82786ec8d1869c
parent 1654c9e1c00cb41de392880adf7c3a5a558270b3
author Tony Wickham <twickham@google.com> 1534876823 -0700
committer Tony Wickham <twickham@google.com> 1535671345 -0700

Add undo snackbar for deleting items

- Add methods to ModelWriter to prepareForUndoDelete, then
  enqueueDeleteRunnable, followed by commitDelete or abortDelete.
- Add Snackbar floating view
- Show Undo snackbar when dropping or flinging to delete target; if the
  undo action is clicked, we abort the delete, otherwise we commit it.

Bug: 24238108
Change-Id: I9997235e1f8525cbb8b1fa2338099609e7358426