/usr/share/glib-2.0/schemas/ is in gnome-settings-daemon-schemas 3.28.1-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.enums.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.peripherals.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.peripherals.wacom.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.color.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.datetime.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.housekeeping.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.keyboard.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.media-keys.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.orientation.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.power.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.print-notifications.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.sharing.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.xrandr.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.settings-daemon.plugins.xsettings.gschema.xml