Examine source code of Black Metal Pattern

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#1f1f1f",
      "tab_background_text": "#d6d6d6"
    }
  },
  "version": "2.0",
  "name": "Black Metal Pattern",
  "manifest_version": 2,
  "description": "Just something I whipped for myself, and now you can have it."
}