Examine source code of Merge Windows

{
  "manifest_version": 2,
  "name": "Merge Windows",
  "version": "1.0",
  "description": "Merge all windows into the current window",
  "permissions": [
    "tabs",
    "windows"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d013147a-9ace-42e7-a655-854e59645c84}",
      "strict_min_version": "116.0"
    }
  },
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "browser_action": {
    "default_title": "Merge Windows",
    "default_popup": "popup.html",
    "default_icon": {
      "64": "icon64.png",
      "128": "icon128.png"
    }
  }
}