Examine source code of Fun tab

{
  "manifest_version": 2,
  "name": "Fun tab",
  "description": "Opens random funny images and motivates users, which is a powerful upgrade",
  "version": "1.0",
  "icons": {
    "32": "icons/logo_32.png",
    "64": "icons/logo_64.png"
  },
  "chrome_url_overrides": {
    "newtab": "tabs.html"
  },
  "applications": {
    "gecko": {
      "strict_min_version": "59.0a2",
      "id": "{0bf5a02f-2753-4d8e-96b4-3e49b244f854}"
    }
  }
}