make StackingClient dispatch to either ash or desktop

chrome/browser/ui/aura/stacking_client_aurawin.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 "chrome/browser/ui/aura/stacking_client_aurawin.h"
+
+#include "ash/shell.h"
+#include "ui/aura/desktop/desktop_stacking_client.h"
+#include "ui/aura/focus_manager.h"
+#include "ui/aura/root_window.h"
+#include "ui/aura/window.h"
+#include "ui/views/widget/desktop_native_widget_aura.h"
+
+StackingClientAuraWin::StackingClientAuraWin() {
+  desktop_stacking_client_.reset(new aura::DesktopStackingClient);
+}
+
+StackingClientAuraWin::~StackingClientAuraWin() {
+}
+
+aura::Window* StackingClientAuraWin::GetDefaultParent(aura::Window* context,
+                                                      aura::Window* window,
+                                                      const gfx::Rect& bounds) {
+  if (chrome::GetHostDesktopTypeForNativeView(context) ==

[Ben Goodger (Google), 2012/11/12 16:49:33]

on linux this will only ever return HDT_NATIVE right now, but that's fine.

[scottmg, 2012/11/12 18:03:53]

Right, yeah. So, should be OK to be just StackingClientAura instead like you
say.

+      chrome::HOST_DESKTOP_TYPE_ASH) {
+    return ash::Shell::GetInstance()->stacking_client()->GetDefaultParent(
+        context, window, bounds);
+  }
+  return desktop_stacking_client_->GetDefaultParent(context, window, bounds);
+}