Examine source code of Summer Time..

{
  "theme": {
    "images": {
      "theme_frame": "SummerTimeHCustom.jpg"
    },
    "colors": {
      "frame": "#050505",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Summer Time..",
  "manifest_version": 2,
  "description": "art, painting, sky, grass, purple flowers, abstract, plants, leaves, summer, spring. My wallpaper that matches can be found at: <a href=\"https://outgoing.prod.mozaws.net/v1/2f9b44834929178a214e10ec3913f9e01fd8aa05cd6889d99a743aa739cf7d2b/http%3A//nature.desktopnexus.com/wallpaper/643752/\" rel=\"nofollow\">http://nature.desktopnexus.com/wallpaper/643752/</a>"
}