Examine source code of Language Quick Switch

{
  "manifest_version": 2,
  "name": "Language Quick Switch",
  "version": "1.0",
  "description": "Quickly toggle between your preferred languages on multilingual websites.",
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon.png"
  },
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f5fd4642-e264-4e10-8a7f-606ace984f0d}"
    }
  }
}