Examine source code of URL Shortener

{
  "manifest_version": 2,
  "name": "Word Counter",
  "version": "1.0",
  "description": "Counts the occurrence of the word 'world' on a webpage",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9ad4621d-3432-4e3a-9d40-5106cc7a40c5}"
    }
  }
}