Makes MouseWatcher work while in metro mode

ui/views/widget/desktop_aura/desktop_event_client.cc

Index: ui/views/widget/desktop_aura/desktop_event_client.cc
diff --git a/ui/views/widget/desktop_aura/desktop_event_client.cc b/ui/views/widget/desktop_aura/desktop_event_client.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fe85a7247bc2ed530197be26fcc2bf5eadc98398
--- /dev/null
+++ b/ui/views/widget/desktop_aura/desktop_event_client.cc
@@ -0,0 +1,26 @@
+// Copyright 2013 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/views/widget/desktop_aura/desktop_event_client.h"
+
+#include "ui/aura/env.h"
+
+namespace views {
+
+DesktopEventClient::DesktopEventClient() {
+}
+
+DesktopEventClient::~DesktopEventClient() {
+}
+
+bool DesktopEventClient::CanProcessEventsWithinSubtree(
+    const aura::Window* window) const {
+  return true;
+}
+
+ui::EventTarget* DesktopEventClient::GetToplevelEventTarget() {
+  return aura::Env::GetInstance();
+}
+
+}  // namespace views