Examine source code of piyocat

{
  "theme": {
    "images": {
      "theme_frame": "hougan.PNG"
    },
    "colors": {
      "frame": "#211b1b",
      "tab_background_text": "#592829"
    }
  },
  "version": "2.0",
  "name": "piyocat",
  "manifest_version": 2,
  "description": "ねこがなげる"
}