Fixes issue with accelerators when a menu is open

ash/accelerators/accelerator_dispatcher.cc

Index: ash/accelerators/accelerator_dispatcher.cc
diff --git a/ash/accelerators/accelerator_dispatcher.cc b/ash/accelerators/accelerator_dispatcher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..46d7beccc1212d59d59f1e3a352078ba9e525d05
--- /dev/null
+++ b/ash/accelerators/accelerator_dispatcher.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 "ash/accelerators/accelerator_dispatcher.h"
+
+namespace ash {
+
+AcceleratorDispatcher::AcceleratorDispatcher(
+    MessageLoop::Dispatcher* nested_dispatcher)
+    : nested_dispatcher_(nested_dispatcher) {
+  DCHECK(nested_dispatcher_);
+}
+
+}  // namespace ash