Ostensibly a blank New Tab Page, but with a colour and background of your choice, and an optional launcher
Click the icon to reveal options for background colour, patterns and textures, and to add a launcher for pages such as Bookmarks and History.
The background can be saved as an image file via the toolbar icon's context menu. On Chrome OS, it can be set as the desktop wallpaper via the same menu.
⚠ This extension is a replacement for your current New Tab Page, it doesn't simply add a background to it.