Examine source code of UA Switcher

{
  "description": "User Agent Switcher 是一款强大的工具，可帮助用户模拟不同设备访问网站，同时助力开发者测试 Bot 屏蔽与爬虫爬取状态，轻松掌握网站兼容性与安全性。User Agent Switcher is a powerful tool that enables users to simulate website access from different devices while helping developers test Bot blocking and spider crawling status, easily mastering website compatibility and security.",
  "manifest_version": 2,
  "name": "UA Switcher",
  "version": "1.2",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "storage",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "uaswitcher@mxdyeah.top"
    }
  },
  "browser_action": {
    "default_icon": {
      "19": "icons/icon-19.png",
      "38": "icons/icon-38.png"
    },
    "default_title": "Choose a UA!",
    "default_popup": "popup.html"
  }
}