gentoo-overlay/xfce-base/xfce4-session/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
  <herd>xfce</herd>
  <use>
    <flag name="consolekit">Enable authentication support using <pkg>sys-auth/consolekit</pkg></flag>
    <flag name="gnome-keyring">Enable password storage support using <pkg>gnome-base/gnome-keyring</pkg></flag>
  </use>
</pkgmetadata>