Examine source code of Volume Booster

{
  "manifest_version": 3,
  "name": "Volume Booster",
  "version": "1.0",
  "description": "Boost the volume of web pages up to 600%.",
  "author": "Volume Booster <volumeboosterhelp@gmail.com>",
  "browser_specific_settings": {
    "gecko": {
      "id": "volumeboosterhelp@gmail.com",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "storage"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_title": "Volume Booster"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "all_frames": true,
      "run_at": "document_idle"
    }
  ]
}