I used assets from http://chromium-assets.appspot.com/ to change some window control buttons for the Zukitre theme found on gnome-look.
Zukitre is GPL. I assume the assets I used are of a compatible license as they are pulled from the Chromium OS project by the website linked above.
Feel free to edit or remake the theme. I would love it for someone with more time, skill, and dedication to make a better version of this, the Chrome OS theme being a much desired theme (entire distros are coming up to replicate it), and all of the assets are readily available.
tl;dr: if you can, make a better version of this.
This is an xfwm4 theme that is meant to be paired with Zukitre theme found on gnome-look. I personally had errors with the indicator on the panel being a gray color instead of black, so I set the panel to use a pure black color instead.