Examine source code of PopOut

{
  "manifest_version": 2,
  "name": "PopOut",
  "short_name": "PopOut",
  "version": "1.0",
  "description": "Quickly move a group of tabs into a new window. PopOut adds a 'Pop out tabs to right' button to your menu bar.",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "logo.png",
    "default_title": "Pop out tabs to right"
  }
}