Change namespace from ui to gfx for NativePixmap related code

ui/ozone/platform/headless/headless_surface_factory.h

 // 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.
 
 #ifndef UI_OZONE_PLATFORM_HEADLESS_HEADLESS_SURFACE_FACTORY_H_
 #define UI_OZONE_PLATFORM_HEADLESS_HEADLESS_SURFACE_FACTORY_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
 #include "ui/ozone/public/gl_ozone.h"
 #include "ui/ozone/public/surface_factory_ozone.h"
 
 namespace ui {
 
 class HeadlessWindowManager;
 
 class HeadlessSurfaceFactory : public SurfaceFactoryOzone {
  public:
   HeadlessSurfaceFactory();
   explicit HeadlessSurfaceFactory(HeadlessWindowManager* window_manager);
   ~HeadlessSurfaceFactory() override;
 
   // SurfaceFactoryOzone:
   std::vector<gl::GLImplementation> GetAllowedGLImplementations() override;
   GLOzone* GetGLOzone(gl::GLImplementation implementation) override;
   std::unique_ptr<SurfaceOzoneCanvas> CreateCanvasForWidget(
       gfx::AcceleratedWidget w) override;
-  scoped_refptr<NativePixmap> CreateNativePixmap(
+  scoped_refptr<gfx::NativePixmap> CreateNativePixmap(
       gfx::AcceleratedWidget widget,
       gfx::Size size,
       gfx::BufferFormat format,
       gfx::BufferUsage usage) override;
 
  private:
   HeadlessWindowManager* window_manager_;
 
   std::unique_ptr<GLOzone> osmesa_implementation_;
 
   DISALLOW_COPY_AND_ASSIGN(HeadlessSurfaceFactory);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_HEADLESS_HEADLESS_SURFACE_FACTORY_H_