/usr/share/vala-0.18/vapi/gdk-x11-3.0.deps is in valac-0.18-vapi 0.18.1-0ubuntu11.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | gio-2.0
gdk-3.0
gdk-pixbuf-2.0
cairo
pango
pangocairo
x11
|