Examine source code of Domain Checker

{
  "description": "Checks if domain of opened url, is registered within last 12 months.",
  "manifest_version": 2,
  "name": "Domain Registration Date Checker",
  "version": "1.0",
  "icons": {
    "48": "icons/on.svg"
  },
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "activeTab",
    "tabs",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "jquery-3.2.1.min.js",
        "bootstrap-3.3.7/js/bootstrap.min.js",
        "registry_check.js"
      ]
    }
  ],
  "page_action": {
    "default_title": "Is website recently registered?",
    "default_popup": "registry_check.html",
    "default_icon": "icons/on.svg"
  },
  "background": {
    "scripts": [
      "jquery-3.2.1.min.js",
      "moment-2.18.1.min.js",
      "background.min.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7bd0edac-f557-4e9e-8d2e-381f626a8673}"
    }
  }
}