Examine source code of Ubuntu Gray Scratch

{
  "theme": {
    "images": {
      "theme_frame": "ubuntu_gray_scratch_header.png"
    },
    "colors": {
      "frame": "#cccccc",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Ubuntu Gray Scratch",
  "manifest_version": 2,
  "description": "Another scratch persona with gray. This promotes Linux Ubuntu and is compatible with vertical side bar"
}