Examine source code of poptofocus

{
  "name": "poptofocus",
  "version": "1.5.1",
  "manifest_version": 2,
  "description": "Open current tab in a popup to focus on it",
  "permissions": [
    "contextMenus",
    "tabs"
  ],
  "icons": {
    "48": "48.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": "32.png",
    "default_title": "Open current tab in a popup"
  }
}