Examine source code of Chess.com clock warning

{
  "manifest_version": 3,
  "name": "Chess.com clock warning",
  "version": "0.1.3",
  "content_scripts": [
    {
      "matches": [
        "*://*.chess.com/*"
      ],
      "css": [],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{e55b9195-670b-4e93-aa8e-950fe8a2f84e}",
      "strict_min_version": "42.0"
    }
  }
}