Examine source code of AudioNormalizer

{
  "manifest_version": 3,
  "name": "AudioNormalizer",
  "version": "1.4",
  "browser_specific_settings": {
    "gecko": {
      "id": "audionormalizer@tuextension.com",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "permissions": [
    "storage",
    "activeTab",
    "tabs"
  ],
  "icons": {
    "256": "icon.png"
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "256": "icon.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}