Examine source code of Simple UserAgent Spoofing

{
  "manifest_version": 2,
  "name": "Custom User Agent Spoofer",
  "version": "1.0",
  "description": "Spoof your user agent and block browser fingerprinting headers.",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icon.png"
    }
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a7fed8e8-d635-42b2-9dc5-448e34705772}"
    }
  }
}