Examine source code of Platform spoofer

{
  "manifest_version": 2,
  "name": "Platform spoofer",
  "version": "0.1",
  "description": "Fakes navigator.platform",
  "browser_specific_settings": {
    "gecko": {
      "id": "platform-spoofer@leopold",
      "strict_min_version": "57.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "platform-spoofer.js"
      ]
    }
  ],
  "permissions": [
    "storage"
  ],
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  }
}