Examine source code of Universal VAT Calculator

{
  "name": "Universal VAT Calculator",
  "version": "1.0.1",
  "description": "Add VAT to a price or take VAT off a price in a few keystrokes with our handy universal VAT calculator",
  "page_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "img/16.png",
      "32": "img/32.png",
      "48": "img/48.png",
      "128": "img/128.png"
    }
  },
  "icons": {
    "16": "img/16.png",
    "32": "img/32.png",
    "48": "img/48.png",
    "128": "img/128.png"
  },
  "manifest_version": 2,
  "author": "https://vatulator.com"
}