Obsolete the ozone code path in ui/views/

ui/views/widget/desktop_aura/desktop_window_tree_host_ozone.cc

 // 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/aura/window_tree_host.h"
-#include "ui/views/widget/desktop_aura/desktop_factory_ozone.h"
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host.h"
 
 namespace views {
 
 DesktopWindowTreeHost* DesktopWindowTreeHost::Create(
     internal::NativeWidgetDelegate* native_widget_delegate,
     DesktopNativeWidgetAura* desktop_native_widget_aura) {
-  DesktopFactoryOzone* d_factory = DesktopFactoryOzone::GetInstance();
-
-  return d_factory->CreateWindowTreeHost(native_widget_delegate,
-                                         desktop_native_widget_aura);
+  NOTREACHED() << "Ozone builds should use DesktopWindowTreeHostMus codepath.";
+  return nullptr;
 }
 
 }  // namespace views