Examine source code of GWA Calculator

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 2,
  "name": "GWA Calculator",
  "description": "A clean and simple GWA calculator",
  "version": "1.1",
  "browser_action": {
    "default_icon": "icon128.png",
    "default_popup": "calculator.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{62bc2819-bde6-49d8-9010-8592b6c2b75e}"
    }
  }
}