Examine source code of Bubbles bubbles bubbles

{
  "theme": {
    "images": {
      "theme_frame": "firefox_bubbles.png"
    },
    "colors": {
      "frame": "#525252",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "Bubbles bubbles bubbles",
  "manifest_version": 2,
  "description": "Bubbles"
}