Examine source code of New Window Block

{
  "manifest_version": 3,
  "name": "New Window Block",
  "version": "1.1",
  "description": "Blocks new tabs/windows for blocked domains.",
  "permissions": [
    "storage",
    "scripting",
    "tabs"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "new.window.block@hgexample1.com"
    }
  }
}