ash: Add RootWindowHostFactory class.

ash/host/root_window_host_factory.cc

+// 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/host/root_window_host_factory.h"
+
+#include "ui/aura/root_window_host.h"
+
+namespace {
+
+class RootWindowHostFactoryImpl : public ash::RootWindowHostFactory {
+ public:
+  RootWindowHostFactoryImpl() {}
+
+  // Overridden from RootWindowHostFactory:
+  virtual aura::RootWindowHost* CreateRootWindowHost(
+      const gfx::Rect& initial_bounds) OVERRIDE {
+    return aura::RootWindowHost::Create(initial_bounds);
+  }
+};
+
+}
+
+namespace ash {
+
+// static
+RootWindowHostFactory* RootWindowHostFactory::Create() {
+  return new RootWindowHostFactoryImpl;
+}
+
+}  // namespace ash