Examine source code of Square Calculator

{
  "manifest_version": 2,
  "name": "Square Calculator",
  "version": "1.0",
  "description": "Calculates the perimeter and area of a square",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Square Calculator",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{780679d6-4fbf-4d42-8f23-c4ac49835f14}"
    }
  }
}