Implement message center on Windows

ui/message_center/message_center_tray_host.cc

Index: ui/message_center/message_center_tray_host.cc
diff --git a/ui/message_center/message_center_tray_host.cc b/ui/message_center/message_center_tray_host.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1afc040b93cfd7cf7ab33ddd238f460a9adcd0b3
--- /dev/null
+++ b/ui/message_center/message_center_tray_host.cc
@@ -0,0 +1,15 @@
+// Copyright (c) 2012 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 "ui/message_center/message_center_tray_host.h"
+
+namespace ui {
+
+#if !defined(ENABLE_MESSAGE_CENTER)
+static MessageCenterTrayHost* MessageCenterTrayHost::Create() {
+  return NULL;
+}
+#endif  // !defined(ENABLE_MESSAGE_CENTER)
+
+}  // namespace ui