Examine source code of UA Override

{
  "manifest_version": 2,
  "name": "UA Override",
  "version": "1.0.0",
  "description": "Override the browser User-Agent header for all requests. Choose from desktop, mobile, and bot presets or enter custom.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{336c885d-ef7f-4cd2-8503-a22908a5bb71}",
      "strict_min_version": "96.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action": {
    "default_icon": {
      "16": "img/icon16.png",
      "32": "img/icon32.png",
      "48": "img/icon48.png",
      "96": "img/icon96.png",
      "128": "img/icon128.png"
    },
    "default_title": "UA Override",
    "default_popup": "js/popup.html"
  },
  "icons": {
    "16": "img/icon16.png",
    "32": "img/icon32.png",
    "48": "img/icon48.png",
    "96": "img/icon96.png",
    "128": "img/icon128.png"
  },
  "permissions": [
    "tabs",
    "storage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": false
  }
}