Examine source code of Tab Count

{
  "manifest_version": 2,
  "name": "Tab Count",
  "version": "1.1resigned1",
  "applications": {
    "gecko": {
      "id": "tabcount@grepper.net"
    }
  },
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "Tab Count",
    "default_area": "tabstrip",
    "browser_style": true
  }
}