Examine source code of Fun 2048 Game

{
  "manifest_version": 2,
  "short_name": "2048",
  "name": "2048",
  "description": "Simple 2048 game",
  "version": "1.2resigned1",
  "icons": {
    "128": "128.png"
  },
  "browser_action": {
    "default_icon": "128.png",
    "default_title": "2048",
    "default_popup": "index.html"
  },
  "permissions": [
    "unlimitedStorage",
    "notifications",
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d00eef4c-0c08-42b6-b540-b7096384768c}"
    }
  }
}