Examine source code of Zenlo volume optimizer

{
  "manifest_version": 3,
  "name": "Zenlo volume optimizer",
  "version": "3.8.3",
  "description": "Boosts the volume and enhances the audio of videos on any website.",
  "permissions": [
    "activeTab",
    "scripting",
    "storage"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": "icon-default.png"
  },
  "icons": {
    "128": "icon-default.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "styles.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "optimizer@zenlo.com"
    }
  }
}