Examine source code of firefox-mac

{
  "theme": {
    "images": {
      "theme_frame": "firefox-mac-pro.jpg"
    },
    "colors": {
      "frame": "#15111c",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "firefox-mac",
  "manifest_version": 2
}