After analyzing bug #628146, under wayland, gudev is mandatory in gsd-device-manager-udev.c.
Package-Manager: Portage-2.3.7, Repoman-2.3.3
REQUIRED_USE="
input_devices_wacom? ( udev )
smartcard? ( udev )
+ wayland? ( udev )
"
KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~ia64 ~ppc ~ppc64 ~sparc ~x86 ~x86-fbsd ~amd64-linux ~x86-linux ~x86-solaris"
COMMON_DEPEND="
>=dev-libs/glib-2.44.0:2[dbus]
- >=x11-libs/gtk+-3.15.3:3[X]
+ >=x11-libs/gtk+-3.15.3:3[X,wayland?]
>=gnome-base/gnome-desktop-3.11.1:3=
>=gnome-base/gsettings-desktop-schemas-3.23.3
>=gnome-base/librsvg-2.36.2:2