Examine source code of easily Text Counter

{
  "manifest_version": 3,
  "name": "Text Counter",
  "version": "1.0",
  "description": "選択した文字数をカウントするFirefox拡張機能",
  "permissions": [
    "contextMenus",
    "notifications"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "48": "icons/48.png",
    "96": "icons/96.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{368e2475-b6e3-4549-aa15-2b626e28a490}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}