Examine source code of VolumeBoost Mini

{
  "manifest_version": 2,
  "name": "VolumeBoost Mini",
  "version": "1.0",
  "description": "Boost volume up to 200% for in-page audio/video using Web Audio API (local only).",
  "icons": {},
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "volumeboost.js"
      ],
      "css": [
        "volumeboost.css"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "storage",
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{22d779f8-9d8b-449c-a9af-8bc11ff6add0}"
    }
  }
}