Fix NPE when mDataDir is null

It's unclear how mDataDir can be null, but adding this fix would prevent the crashes caused by NPE. The rest of the code seems to be able to handle when mDataDir is null just fine.

Change-Id: Ibd43a0b80a13226cbe4627897040339a7b44dea1
BUG: 332866130
FIXES: 332866130
Test: presubmit
1 file changed