Examine source code of No More Tabs

{
  "version": "3.0.0",
  "manifest_version": 2,
  "name": "No More Tabs",
  "short_name": "NMT",
  "description": "No More Tab: immediately mute new tabs & close them in a few seconds",
  "permissions": [
    "tabs"
  ],
  "browser_action": {
    "default_title": "NMT",
    "default_popup": "assets/html/popupv3.html"
  },
  "icons": {
    "128": "assets/images/logo128.png"
  },
  "background": {
    "scripts": [
      "backgroundv3.js"
    ]
  },
  "web_accessible_resources": [
    "assets/**"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "nomoretabs@apextension.it",
      "strict_min_version": "109.0"
    }
  }
}