Examine source code of Facebook 57

{
  "theme": {
    "images": {
      "theme_frame": "facebook.png"
    },
    "colors": {
      "frame": "#ffffff",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Facebook 57",
  "manifest_version": 2,
  "description": "Use of facebook colors with a custom 57 in the corner to make 'Facebook 57'"
}