Set directory search mode earlier

* The cause of the crash is that in ag/1424283 we set directory search
  mode in onResume in fragment (rather than before onStart), so loader
  and adapter gets old directory search mode (0). Then it will invoke
  DirectoryListLoader.getDefaultDirectories and IllegalArgumentException
  is thrown.

* We set it earlier now so that loader and adapter will set it correctly
  accordingly, which is consistent with the logic prior to ag/1424283.

Bug: 31778407

Test: manual:
  - follow steps to reproduce in the bug
  - verify search actions in tests APK work well

Change-Id: I5b2eaeaac5f3d1b45b9f9be722b76d94035a51e5