Examine source code of Automeet

{
  "name": "Automeet",
  "version": "0.3",
  "description": "Adds google meet link automatically",
  "manifest_version": 2,
  "icons": {
    "48": "icons/icon48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://calendar.google.com/*"
      ],
      "js": [
        "contentScript.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{8f147e4f-0e8c-4e31-aeca-07f5a4c11369}"
    }
  }
}