Examine source code of Custom search engines

{
  "manifest_version": 3,
  "browser_specific_settings": {
    "gecko": {
      "id": "{12345678-1234-1234-1234-1234567890ab}"
    }
  },
  "name": "Custom search engine",
  "description": "This extension is for searching something while watching a video or seeing an image. Currently supported browsers: Firefox, Google Chrome, Microsoft Edge (Bing)",
  "version": "1.1",
  "permissions": [
    "activeTab",
    "management"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "thrift shop online.png",
      "48": "thrift shop online.png",
      "128": "thrift shop online.png"
    }
  }
}