Demo UI made with a help of WUG toolkit (DO NOT SEND TO CQ).

chrome/browser/ui/webui/demo_ui/strings/strings_demo.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_DEMO_UI_STRINGS_STRINGS_DEMO_H_
+#define CHROME_BROWSER_UI_WEBUI_DEMO_UI_STRINGS_STRINGS_DEMO_H_
+
+#include "base/macros.h"
+#include "base/timer/timer.h"
+#include "components/demo_ui/strings/strings_demo_view_model.h"
+
+class StringsDemo : public gen::StringsDemoViewModel {
+ public:
+  StringsDemo();
+  ~StringsDemo() override;
+
+  static void Register();
+
+ private:
+  void Initialize() override;
+  void UpdateClock();
+
+  base::Timer timer_;
+  DISALLOW_COPY_AND_ASSIGN(StringsDemo);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_DEMO_UI_STRINGS_STRINGS_DEMO_H_