Examine source code of Age CALCULATOR Basic

{
  "manifest_version": 2,
  "name": "Age CALCULATOR Basic",
  "version": "1.0",
  "description": "Age CALCULATOR Basic is a utility that allows you to calculate your age through 2 options: date of birth and current date.",
  "permissions": [],
  "browser_action": {
    "default_popup": "game.html",
    "default_icon": {
      "128": "images/age-logo.png"
    }
  },
  "icons": {
    "128": "images/age-logo.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f31d8837-7bcd-4f73-b40c-aafffa83652f}"
    }
  }
}