Examine source code of Autosave Online

{
  "name": "Autosave Online",
  "manifest_version": 2,
  "version": "0.0.5resigned1",
  "description": "GPL-3.0+ A lightweight form-capturing utility.",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "sfwl.js"
      ],
      "all_frames": true,
      "run_at": "document_idle"
    }
  ],
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "browser_style": true,
    "default_icon": "logo.min.svg",
    "default_popup": "asd.html"
  },
  "applications": {
    "gecko": {
      "id": "{a47bd1cb-471b-48c0-89a8-ed4fb9d6567d}"
    }
  }
}