chromium/chrome/test/data/extensions/api_test/override/keyboard/manifest.json

{
  "name": "Keyboard override test",
  "version": "0.1",
  "manifest_version": 2,
  "description": "Test chrome://keyboard override",
  "background": {
    "scripts": ["background.js"]
  },
  "chrome_url_overrides": {
    "keyboard": "keyboard.html"
  }
}