Examine source code of Simple Calculator

{
  "manifest_version": 2,
  "name": "Simple Calculator",
  "version": "2.2",
  "icons": {
    "48": "icons/Icon.png"
  },
  "browser_action": {
    "default_icon": "icons/Icon.png",
    "default_title": "Super Simple Calculator",
    "default_popup": "popup/Popup.html"
  },
  "id": "org.simplecalculator.pto23jfk",
  "browser_specific_settings": {
    "gecko": {
      "id": "{bdc0f9d6-fb6d-403b-b37a-bd495f76996e}"
    }
  }
}