Change namespace from ui to gfx for NativePixmap related code

ui/ozone/public/client_native_pixmap_factory_ozone.cc

 // Copyright 2015 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/ozone/public/client_native_pixmap_factory_ozone.h"
 
 #include "base/trace_event/trace_event.h"
 #include "ui/ozone/platform_object.h"
 #include "ui/ozone/platform_selection.h"
 
 namespace ui {
 
-std::unique_ptr<ClientNativePixmapFactory>
+std::unique_ptr<gfx::ClientNativePixmapFactory>
 CreateClientNativePixmapFactoryOzone() {
   TRACE_EVENT1("ozone", "CreateClientNativePixmapFactoryOzone", "platform",
                GetOzonePlatformName());
-  return PlatformObject<ClientNativePixmapFactory>::Create();
+  return PlatformObject<gfx::ClientNativePixmapFactory>::Create();
 }
 
 }  // namespace ui