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

components/demo_ui/BUILD.gn

Index: components/demo_ui/BUILD.gn
diff --git a/components/demo_ui/BUILD.gn b/components/demo_ui/BUILD.gn
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index 0000000000000000000000000000000000000000..30fa15f7cd37146d7b1bee50f597b6c6c2402ead
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+++ b/components/demo_ui/BUILD.gn
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+# 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",
+  ]
+}