Examine source code of Once Upon

{
  "name": "444444",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "3 - Once Upon a Time in America.png"
    },
    "colors": {
      "frame": "rgba(255, 255, 255, 0)",
      "tab_background_text": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{657a6bbc-09dd-4523-90c8-db71f15b67f0}"
    }
  }
}