Google chrome fixes

Using Mint-X, the Google Chrome window borders incorrectly picked up the
theme_selected_bg_color, which makes them stand harshly against the
window borders. This customization file corrects this to display with the normal
window shading, consistent with Nemo and other desktop components.

OLD:
![Old Chrome](http://i.imgur.com/K3mmK10.png)

NEW:
![New Chrome](http://i.imgur.com/pnyOr42.png)