Try to get rid of all direct references to particular native themes.

ui/views/widget/desktop_aura/desktop_window_tree_host_chromeos.cc

 // Copyright 2016 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_window_tree_host.h"
 
-#include "ui/native_theme/native_theme_aura.h"
+#include "ui/native_theme/native_theme.h"
 
 namespace views {
 
 // static
 DesktopWindowTreeHost* DesktopWindowTreeHost::Create(
     internal::NativeWidgetDelegate* native_widget_delegate,
     DesktopNativeWidgetAura* desktop_native_widget_aura) {
   // DesktopNativeWidgetAura is only used with mus, and MusClient injects the
   // DesktopWindowTreeHost so that this is never called.
   NOTREACHED();
   return nullptr;
 }
 
 // static
 ui::NativeTheme* DesktopWindowTreeHost::GetNativeTheme(aura::Window* window) {
-  return ui::NativeThemeAura::instance();
+  return ui::NativeTheme::GetInstanceForNativeUi();
 }
 
 }  // namespace views