Examine source code of Next.js App Detector

{
  "manifest_version": 2,
  "name": "next.js-app-detector",
  "description": "Detects if a website is built with Next.js",
  "version": "0.0.2",
  "icons": {
    "16": "icon-16.png",
    "128": "icon-128.png"
  },
  "background": {
    "scripts": [
      "background_script.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "16": "icon-16-not-detected.png",
      "128": "icon-128-not-detected.png"
    },
    "default_title": "No Next.js on this page"
  }
}