Examine source code of Silent Timer

{
  "manifest_version": 3,
  "name": "Silent Timer",
  "version": "1.0",
  "description": "Silent ticking timer with sound alert when time is up.",
  "action": {
    "default_popup": "popup.html",
    "default_title": "Silent Timer"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "silent-timer@amo.mozilla.org",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}