Examine source code of Currency Converter

{
  "manifest_version": 2,
  "name": "Currency Converter",
  "version": "1.0",
  "description": "Quy đổi tiền tệ tức thì.",
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_action": {
    "default_icon": "icons/icon.png",
    "default_popup": "popup.html"
  },
  "permissions": [
    "https://api.exchangerate-api.com/"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9444f7bd-9e00-46f9-b15e-53dbefd778da}"
    }
  }
}