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

components/demo_ui/BUILD.gn

+# 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.
+
+import("//components/webui_generator/generator/wug.gni")
+
+wug("demo_wug_generated") {
+  source = "demo.json"
+}
+
+wug("events_demo_wug_generated") {
+  source = "//components/demo_ui/events/events_demo.json"
+}
+
+wug("strings_demo_wug_generated") {
+  source = "strings/strings_demo.json"
+}
+
+wug("reuse_demo_wug_generated") {
+  source = "reuse/reuse_demo.json"
+}
+
+group("demo_ui") {
+  public_deps = [
+    ":demo_wug_generated",
+    ":events_demo_wug_generated",
+    ":strings_demo_wug_generated",
+    ":reuse_demo_wug_generated",
+    "//components/webui_generator",
+  ]
+}