Examine source code of Click Counter

{
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "images/128.png",
    "default_popup": "index.html"
  },
  "default_locale": "en",
  "description": "Count Mouse Button Clicks",
  "icons": {
    "16": "images/16.png",
    "32": "images/32.png",
    "48": "images/48.png",
    "128": "images/128.png"
  },
  "manifest_version": 2,
  "name": "Click Counter",
  "short_name": "Click Counter",
  "update_url": "https://clients2.google.com/service/update2/crx",
  "version": "3.4.1"
}