UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.98 Safari/537.36

Steps to reproduce the problem:
1. Open the Chrome browser.
2. Make sure it is maximized.

What is the expected behavior?
The main window should have the standard minimize, maximize and close buttons on the top right corner of the window.

What went wrong?
The minimize, maximize and close buttons are missing and there seems to be no way to bring them back.

Did this work before? Yes I think the buttons were present in Chrome 56 (I'm not sure since I've not used Chrome for a while).

Chrome version: 57.0.2987.98  Channel: stable
OS Version: Kubuntu 16.10
Flash Version: Shockwave Flash 24.0 r0

The buttons are missing regardless of whether I enable the GTK+ theme or Classic theme in settings. The only workaround I've found is to enable "Use system title bar and borders". This was not necessary in previous versions of Chrome.

Also, the buttons appear if the Chrome window is not maximized.