Examine source code of Currency Converter Widget

{
  "manifest_version": 2,
  "name": "Currency Converter Widget",
  "version": "1.0",
  "description": "Quickly convert currencies in a popup.",
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{2401df8a-47fd-481c-9b49-9332a51932fd}"
    }
  }
}