Examine source code of Money Counter

{
  "manifest_version": 2,
  "name": "Money Counter",
  "description": "Money counter helps you count your money. Add the number of bills and coins  to calculate their total value.",
  "version": "1.0.0",
  "version_name": "1.0.0 beta",
  "browser_action": {
    "default_popup": "index.html",
    "default_title": "Money Counter"
  },
  "icons": {
    "16": "img/icon16.png",
    "32": "img/icon32.png",
    "64": "img/icon64.png",
    "128": "img/icon128.png"
  },
  "offline_enabled": true,
  "update_url": "https://clients2.google.com/service/update2/crx"
}