Examine source code of Clicky Counter

{
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png",
    "default_title": "Click Counter"
  },
  "background": {
    "persistent": false,
    "scripts": [
      "background.js"
    ]
  },
  "name": "Click Counter",
  "manifest_version": 2,
  "description": "Count Mouse Button Clicks. Fast and Simple Clicks Counter for you.",
  "permissions": [
    "storage"
  ],
  "update_url": "https://clients2.google.com/service/update2/crx",
  "version": "1.4",
  "browser_specific_settings": {
    "gecko": {
      "id": "{da1153eb-31c6-47c1-93a4-49e39821b288}"
    }
  }
}