Examine source code of Easy gray gradient

{
  "theme": {
    "images": {
      "theme_frame": "gra.png"
    },
    "colors": {
      "frame": "#404040",
      "tab_background_text": "#d4d4d4"
    }
  },
  "version": "2.0",
  "name": "Easy gray gradient",
  "manifest_version": 2
}