Many people are disappointed that Chrome does not explicitly allow an image to be set as background by right-clicking it. You need to save it to your computer, and then set it as your wallpaper. This is very irritating. Apart from this, Chrome is a perfect web browser. But I know exactly how to enable that.
Just install this extension, and just forget it. When you right-click an image anywhere, you have a new option to set it as your desktop background. You can choose, normally if you want it stretched, centered or tiled, plus some more options before you set it.
Enjoy your new feature. And if you know some tips, or maybe a better option, do tell me in the comments.