Examine source code of JavaScript File Counter

{
  "manifest_version": 2,
  "name": "JavaScript File Counter",
  "version": "1.0",
  "description": "Counts the number of JavaScript files on the current web page.",
  "browser_action": {
    "default_icon": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d0411273-d25d-4bd0-b799-74f196188483}"
    }
  }
}