UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.85 Safari/537.36

Steps to reproduce the problem:
It's a bit more complicated than what I've described above, actually. To reproduce the issue (in Gnome Shell 3.26.2, haven't tested other DEs):

1. Disable system title bars and window borders
2. Go fullscreen either by pressing F11 or by watching a fullscreen video
3.  While keeping the video or browser in fullscreen, switch to another program either through Alt-tab or through the overview (Super-key in Gnome-Shell)
4. Get back to the Chrome window that is in full-screen
5. Exit fullscreen (F11 or Escape)

What is the expected behavior?
The Window buttons should still be there.

What went wrong?
The window buttons disappear and you have to minimize/maximize the window (or re-switch program through Alt-tab and come back) for them to reappear.

Did this work before? No 

Chrome version: 64.0.3282.85  Channel: beta
OS Version: Ubuntu 17.10
Flash Version: Shockwave Flash 28.0 r0

As for the "it never worked" part, I have had this issue consistently since I disabled system title bars and window borders when GTK theming was enabled for Window buttons in Chrome's client-side decorations.

It's obviously a very minor issue (fixed in a split second when it happens, basically no real hassle), but I thought I'd make a bug report anyway in case it can be permanently fixed easily.