Examine source code of Currency Converter Button

{
  "manifest_version": 3,
  "name": "__MSG_extensionName__",
  "version": "1.0",
  "description": "__MSG_extensionDescription__",
  "permissions": [
    "storage",
    "activeTab",
    "scripting"
  ],
  "host_permissions": [
    "https://api.exchangerate-api.com/*"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "128": "icons/icon-128.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e5d1f5c8-1b0d-0c2e-3f0b-5a9f53dfe3cd}"
    }
  }
}