Examine source code of Lichess2Chess

{
  "manifest_version": 3,
  "name": "Lichess2Chess",
  "version": "1.4",
  "description": "Adds Chess.com rating estimate to Lichess.org.",
  "icons": {
    "48": "images/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{aa60beb9-2577-4eea-ae50-14a97ad9653d}"
    }
  },
  "web_accessible_resources": [
    {
      "resources": [
        "regressions.json"
      ],
      "matches": [
        "*://lichess.org/*"
      ]
    }
  ],
  "content_scripts": [
    {
      "matches": [
        "*://lichess.org/*"
      ],
      "js": [
        "lichess2chess.js"
      ]
    }
  ]
}