Examine source code of Cornfield

{
  "theme": {
    "images": {
      "theme_frame": "header-cornfield.jpg"
    },
    "colors": {
      "frame": "#ff9500",
      "tab_background_text": "#0f0f0f"
    }
  },
  "version": "2.0",
  "name": "Cornfield",
  "manifest_version": 2,
  "description": "Amazing wide cornfield landscape!"
}