Examine source code of Age Tracker

{
  "manifest_version": 2,
  "name": "Age Tracker",
  "version": "1.0.1",
  "description": "Track your age based on your birthdate.",
  "author": "sm ehsan",
  "homepage_url": "https://smehsan.com",
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "icons/icon.png"
  },
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d3ecea4f-bb35-405d-9964-2ddfaf36ce3b}"
    }
  }
}