Examine source code of User-Agent Switch

{
  "manifest_version": 2,
  "name": "User-Agent Switch",
  "version": "1.0",
  "description": "Switches the User-Agent to a desktop version for a better web experience.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{3ace31e4-83df-4c6c-9303-82e53ea90c1a}"
    }
  }
}