Examine source code of OldMapsOnline

{
  "manifest_version": 3,
  "name": "OldMapsOnline",
  "description": "__MSG_extDescription__",
  "version": "2.0.0",
  "icons": {
    "16": "images/icon16.png",
    "32": "images/icon32.png",
    "38": "images/icon38.png",
    "48": "images/icon48.png",
    "64": "images/icon64.png",
    "128": "images/icon128.png",
    "256": "images/icon256.png"
  },
  "default_locale": "en",
  "action": {
    "default_icon": {
      "16": "images/icon16.png",
      "32": "images/icon32.png",
      "38": "images/icon38.png",
      "48": "images/icon48.png",
      "64": "images/icon64.png",
      "128": "images/icon128.png",
      "256": "images/icon256.png"
    },
    "default_title": "OldMapsOnline",
    "default_popup": "popup.html"
  },
  "permissions": [
    "storage",
    "webRequest"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a84f601c-824c-4309-95e0-b8df93b459b7}",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}