Examine source code of Three-D chess

{
  "theme": {
    "images": {
      "theme_frame": "chess-large.jpg"
    },
    "colors": {
      "frame": "#636363",
      "tab_background_text": "#302a2a"
    }
  },
  "version": "2.0",
  "name": "Three-D chess",
  "manifest_version": 2,
  "description": "3d chess"
}