xdg-shell-client-protocol.h

[Nicolai Dagestad]

I haven't read the tutorial, but the headers and sources for the protocol are autogenerated.
You should have a tool called wayland-scanner installed and the protocol xml file somwhere on your
filesystem (I am assuming you are working on Linux).
In my case I can generate the file with:
`wayland-scanner client-header /usr/share/wayland-protocols/stable/xdg-shell/xdg-shell.xml xdg-shell-client-protocol.h`

I assume you will also need the public code, you can generate that with `public-code` instead of
`client-header`.

I am not very experienced in working with wayland yet, but from what I have seen in warious project
this is always done by your build system. (And the tooling will probably do it with `wayland-scanner`)

That tutorial seems a bit old, some information in it might be outdated, may I recommend
https://wayland-book.com/xdg-shell-basics.html
The last few chapters aren't really done it seems but it is still a good way to get familiar with
wayland at a low level.