/usr/include/ is in libsnapd-glib-dev 1.39-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/snapd-glib/
/usr/include/snapd-glib/snapd-glib/
/usr/include/snapd-glib/snapd-glib/snapd-alias.h
/usr/include/snapd-glib/snapd-glib/snapd-app.h
/usr/include/snapd-glib/snapd-glib/snapd-assertion.h
/usr/include/snapd-glib/snapd-glib/snapd-auth-data.h
/usr/include/snapd-glib/snapd-glib/snapd-change.h
/usr/include/snapd-glib/snapd-glib/snapd-channel.h
/usr/include/snapd-glib/snapd-glib/snapd-client.h
/usr/include/snapd-glib/snapd-glib/snapd-connection.h
/usr/include/snapd-glib/snapd-glib/snapd-enum-types.h
/usr/include/snapd-glib/snapd-glib/snapd-error.h
/usr/include/snapd-glib/snapd-glib/snapd-glib.h
/usr/include/snapd-glib/snapd-glib/snapd-icon.h
/usr/include/snapd-glib/snapd-glib/snapd-login.h
/usr/include/snapd-glib/snapd-glib/snapd-plug.h
/usr/include/snapd-glib/snapd-glib/snapd-price.h
/usr/include/snapd-glib/snapd-glib/snapd-screenshot.h
/usr/include/snapd-glib/snapd-glib/snapd-slot.h
/usr/include/snapd-glib/snapd-glib/snapd-snap.h
/usr/include/snapd-glib/snapd-glib/snapd-system-information.h
/usr/include/snapd-glib/snapd-glib/snapd-task.h
/usr/include/snapd-glib/snapd-glib/snapd-user-information.h
/usr/include/snapd-glib/snapd-glib/snapd-version.h