Examine source code of Heading Extractor

{
  "browser_specific_settings": {
    "gecko": {
      "id": "danieldetailingaz@gmail.com"
    }
  },
  "name": "__MSG_appName__",
  "version": "1.8.2",
  "manifest_version": 3,
  "description": "__MSG_appDescription__",
  "icons": {
    "16": "images/16.png",
    "128": "images/128.png"
  },
  "default_locale": "en",
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "scripts/libs/jquery.min.js",
        "scripts/libs/popper.min.js",
        "scripts/libs/bootstrap.min.js"
      ],
      "run_at": "document_idle",
      "all_frames": false
    }
  ],
  "action": {
    "default_icon": {
      "16": "images/16.png"
    },
    "default_title": "Heading Extractor",
    "default_popup": "danieldetailingaz.html"
  },
  "web_accessible_resources": [
    {
      "resources": [
        "images/*.jpeg",
        "images/*.png"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "content_security_policy": {
    "extension_pages": "script-src 'self'; object-src 'self'"
  }
}