Examine source code of Bucky Cap

{
  "theme": {
    "images": {
      "theme_frame": "firefox_newcap_header3.jpg"
    },
    "colors": {
      "frame": "#4172b3",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Bucky Cap",
  "manifest_version": 2,
  "description": "Sure it's not Steve Rogers, but man-oh-man can he still throw his mighty shield.  From Marvel Comics, the new Captain America."
}