Found this when I've decided to use my own theme colors in the browser...

This will cover the basic of basics for creating your own themes for the Chrome (or Chromium) browser.

Some straight-forward ways to do it are mentioned here below.

1. Online theme creator:
Chrome Theme Creator - Create Custom Google Chrome Themes Online

2. Install the Theme Creator extension:

Example using the online theme creator:
-choose a theme name
-choose a background color
-pick your colors
-pack & install/download theme (*.crx file)

Preview example: my theme called DayBreak
Click image for larger version

Simple colors, gradients or pictures allowed for the backgrounds...