Examine source code of SupplyWishList.org

{
  "manifest_version": 3,
  "name": "SupplyWishList.org",
  "version": "0.1.0",
  "icons": {
    "16": "icon_16.png",
    "32": "icon_32.png",
    "48": "icon_48.png",
    "128": "icon_128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.amazon.com/*"
      ],
      "js": [
        "background.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "admin@supplywishlist.org"
    }
  }
}