Wrap show dialog fragment in isSafeToCommitTransactions check

The dialog fragment is shown from an onClick handler which can be
run after onSaveInstanceState is called which results in the
IllegalStateException. Our base activity classes already have a
method to check for this, so call it before attempting to show the
dialog fragment.

Also delete an unused class.

Test: N/A

Bug: 33341841
Change-Id: I1e27bd473666025251c95f8d497c71a248a5a2c8
3 files changed