Examine source code of Auto Close Tab Extension

{
  "manifest_version": 2,
  "name": "Auto Close Tab Extension",
  "version": "1.8",
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.uppclonline.com/*",
        "https://kescocp.eeslsmartmeter.in/*",
        "https://jhatpat.uppcl.org/*",
        "https://niveshmitra.up.nic.in/*",
        "https://appsavy.com/*",
        "https://consumer.uppcl.org/*",
        "https://www.kesco.co.in/*",
        "https://kesco.co.in/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "autoclose@myextension",
      "strict_min_version": "91.0"
    }
  }
}