Examine source code of Restore Birdie

{
  "manifest_version": 2,
  "name": "Restore Birdie",
  "version": "1.1",
  "description": "Just don't let them kill the birdie.",
  "icons": {
    "16": "images/icon-16x16.png",
    "32": "images/icon-32x32.png",
    "48": "images/icon-48x48.png",
    "128": "images/icon-128x128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://twitter.com/*",
        "https://x.com/*"
      ],
      "js": [
        "contentScript.js"
      ]
    }
  ],
  "permissions": [
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{15ce6a8c-4a25-4ab7-b893-019e94115b41}"
    }
  }
}