Add webusb notification UI code

components/webusb/webusb_browser_client.cc

Index: components/webusb/webusb_browser_client.cc
diff --git a/components/webusb/webusb_browser_client.cc b/components/webusb/webusb_browser_client.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2f7cf87d8582e4a83f0d9b4229192660097e854b
--- /dev/null
+++ b/components/webusb/webusb_browser_client.cc
@@ -0,0 +1,23 @@
+// 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.
+
+#include "components/webusb/webusb_browser_client.h"
+
+namespace webusb {
+
+namespace {
+
+WebUsbBrowserClient* webusb_browser_client = nullptr;
+
+}  // namespace
+
+WebUsbBrowserClient* WebUsbBrowserClient::Get() {
+  return webusb_browser_client;
+}
+
+void WebUsbBrowserClient::Set(WebUsbBrowserClient* client) {
+  webusb_browser_client = client;
+}
+
+}  // namespace webusb