Refactor SearchManager:

- Move SearchManager out of BaseActivity.
- Refactor usage of onCurrentDirectoryChanged(int anim).
- Cancel search when directory changes.
- Enable testing for cancelling search when directory changes.
- Avoid recreating action bar when only the content of the directory is
  changed.

BUG=26495573

Change-Id: I1400090fcb529ad3905018d1640fdb7416542989
7 files changed