Examine source code of Temperature Converter

{
  "manifest_version": 3,
  "name": "Temperature Converter",
  "version": "1.0",
  "description": "Convert temperatures between Celsius, Fahrenheit, and Kelvin",
  "action": {
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    },
    "default_popup": "popup.html"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "Temperature111-converter@unique.extension.id"
    }
  }
}