0. Install xbacklight: sudo apt-get install xbacklight
1. Go to System Settings > Tweaks > Shortcuts
2. Press the (+) sign at the lower left
3. Create a shortcut named "Brightness up"
4. Click the Shortcut button and press F7 to assign it (brightness increase key on the Chromebook)
3. Create a shortcut named "Brightness up"
4. Click the Shortcut button and press F7 to assign it (brightness increase key on the Chromebook)
5. In the Command field, type "xbacklight -inc 10"
6. Click on the green (+) button to save the shortcut.
6. Click on the green (+) button to save the shortcut.
7. Create a shortcut named "Brightness down"
8. Click the Shortcut button and press F6 to assign it (brightness increase key on the Chromebook)
9. In the Command field, type "xbacklight -dec 10"
10. Click on the green (+) button to save the shortcut.
10. Click on the green (+) button to save the shortcut.
