Examine source code of Any Unit Converter

{
  "manifest_version": 3,
  "name": "Any Unit Converter",
  "version": "1.0.1",
  "description": "Fast, compact unit converter for Length, Weight, Area, Volume, Temperature and Time.",
  "action": {
    "default_popup": "index.html",
    "default_icon": {
      "48": "icons/icon48.png",
      "64": "icons/icon64.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "48": "icons/icon48.png",
    "64": "icons/icon64.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{20c8ed18-b939-4729-9e0c-8d03609a2037}"
    }
  }
}