Examine source code of Auto Toggle Vertical Tab

{
  "manifest_version": 2,
  "name": "Auto Toggle Vertical Tab",
  "description": "Automatically toggle vertical tab based on the width of currently focused window.",
  "version": "1.2.1",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "64": "icon/64.png",
    "128": "icon/128.png"
  },
  "permissions": [
    "browserSettings",
    "storage"
  ],
  "homepage_url": "https://github.com/regunakyle/firefox-auto-vertical-tab",
  "browser_specific_settings": {
    "gecko": {
      "id": "{b7eef7b5-1504-4fe1-a48b-3d08859a7761}",
      "strict_min_version": "142.0"
    }
  },
  "background": {
    "persistent": false,
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Firefox Auto Vertical Tab",
    "default_popup": "popup.html"
  }
}