Examine source code of Shoe Sizer for Android

{
  "manifest_version": 3,
  "name": "Shoe Sizer for Android",
  "version": "1.0",
  "description": "Convert shoe sizes for Men, Women, and Children across US, EU, UK, JP, AU, CN on mobile and desktop.",
  "permissions": [],
  "host_permissions": [],
  "action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "shoe_sizer_android@benes.iwp.edu",
      "strict_min_version": "120.0"
    },
    "gecko_android": {
      "strict_min_version": "120.0"
    }
  }
}