D18653: [PreviewJob] Also pass along that we're the thumbnailer when stat'ing file

[Kai Uwe Broulik]

broulik added a dependent revision: D18654: [fonts:/ KIO] Implement stat() call.

REPOSITORY
  R241 KIO

REVISION DETAIL
  https://phabricator.kde.org/D18653

To: broulik, #frameworks, dfaure
Cc: kde-frameworks-devel, michaelh, ngraham, bruns