Examine source code of Apple Links

{
  "manifest_version": 2,
  "name": "Apple Links",
  "version": "1.0",
  "icons": {
    "128": "media/ext/logo_128x128.png"
  },
  "description": "Quick links for Apple users (including iCloud).",
  "browser_action": {
    "default_icon": "media/ext/logo_300x300.png",
    "default_popup": "app.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "apple-links@tobyworld.eu"
    }
  }
}