chromium/chrome/test/data/extensions/icon_size_test/manifest.json

{
  "name": "A browser action with a large icon",
  "version": "1.0",
  "manifest_version": 2,
  "permissions": [
    "tabs", "http://*/*"
  ],
  "browser_action": {
      "name": "Make this page red",
      "icons": ["icon.png"]
  }
}