Examine source code of SM Snake Game

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Snake Game",
  "short_name": "Snake",
  "description": "Play Snake Game in your browser as a popup",
  "version": "1.4.0.2",
  "version_name": "V1.4.0.1 beta",
  "manifest_version": 2,
  "browser_action": {
    "default_icon": "images/icons/icon.png",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "images/icons/16x16.png",
    "32": "images/icons/32x32.png",
    "48": "images/icons/48x48.png",
    "128": "images/icons/128x128.png"
  },
  "permissions": [
    "storage"
  ]
}