Moves management of transients out of Window

ui/aura/client/transient_window_client.cc

Index: ui/aura/client/transient_window_client.cc
diff --git a/ui/aura/client/transient_window_client.cc b/ui/aura/client/transient_window_client.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c835f420a9815c285fad95aba82833dc8b09cc03
--- /dev/null
+++ b/ui/aura/client/transient_window_client.cc
@@ -0,0 +1,25 @@
+// Copyright (c) 2014 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/aura/client/transient_window_client.h"
+
+namespace aura {
+namespace client {
+
+namespace {
+
+TransientWindowClient* instance = NULL;
+
+}  // namespace
+
+void SetTransientWindowClient(TransientWindowClient* client) {
+  instance = client;
+}
+
+TransientWindowClient* GetTransientWindowClient() {
+  return instance;
+}
+
+}  // namespace client
+}  // namespace aura