Examine source code of Prime Number Checker

{
  "manifest_version": 2,
  "name": "Prime Number Checker",
  "version": "1.0",
  "description": "Check if a number is prime with just one click.",
  "icons": {
    "48": "icons/prime-checker-icon-48.png"
  },
  "permissions": [],
  "browser_action": {
    "default_icon": "icons/prime-checker-icon-48.png",
    "default_popup": "popup.html",
    "default_title": "Prime Checker"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{083c02cb-c21f-4ba0-9270-fc94a82b33b6}"
    }
  }
}