Examine source code of Tab Manager for Chrome

{
  "browser_specific_settings": {
    "gecko": {
      "id": "clarkjenifertj@example.com"
    }
  },
  "manifest_version": 3,
  "name": "Tab Manager for Chrome Dev Docs",
  "version": "1.0",
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "action": {
    "default_popup": "popup.html"
  },
  "host_permissions": [
    "https://developer.chrome.com/*"
  ],
  "permissions": [
    "tabGroups"
  ]
}