Examine source code of Chestnuts..

{
  "theme": {
    "images": {
      "theme_frame": "ChestnutsH.jpg"
    },
    "colors": {
      "frame": "#ffffff",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Chestnuts..",
  "manifest_version": 2,
  "description": "autumn, chestnuts, dragonfly, fall, fuzzy, insects, lady bug, ladybug, leaves, nuts, tree, roasted, roast, healthy, food, \t\n\nDesigned by MaDonna\n\nMy wallpaper to match is at: <a href=\"https://outgoing.prod.mozaws.net/v1/c14d292533612cba3536c1f030f93a4077e24bbc1a83957b53ce10534c4bf668/http%3A//nature.desktopnexus.com/wallpaper/1190493/\" rel=\"nofollow\">http://nature.desktopnexus.com/wallpaper/1190493/</a>"
}