Examine source code of Bart Proxy Switcher

{
  "manifest_version": 2,
  "name": "Bart Proxy Switcher",
  "version": "1.0.0",
  "description": "A basic example extension with only required keys",
  "homepage_url": "https://bartproxies.com/",
  "icons": {
    "16": "icons/bart-16.png",
    "24": "icons/bart-24.png",
    "32": "icons/bart-32.png",
    "48": "icons/bart-48.png",
    "96": "icons/bart-96.png",
    "128": "icons/bart-128.png"
  },
  "permissions": [
    "browsingData",
    "storage",
    "unlimitedStorage",
    "proxy",
    "<all_urls>",
    "webRequest",
    "webRequestBlocking",
    "notifications"
  ],
  "browser_action": {
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "worker.js"
    ],
    "persistent": true
  },
  "incognito": "spanning",
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "91.1.0",
      "id": "{423b8733-e7cc-43ae-a1d8-6f89c43e51ab}"
    }
  }
}