ui: Move gl/ directory out of gfx/, up to ui/.

ui/gfx/gl/gpu_preference.h

-// Copyright (c) 2011 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_GFX_GL_GPU_PREFERENCE_H_
-#define UI_GFX_GL_GPU_PREFERENCE_H_
-#pragma once
-
-namespace gfx {
-
-// On dual-GPU systems, expresses a preference for using the integrated
-// or discrete GPU. On systems that have dual-GPU support (see
-// GLContext::SupportsDualGpus), resource sharing only works between
-// contexts that are created with the same GPU preference.
-//
-// This API will likely need to be adjusted as the functionality is
-// implemented on more operating systems.
-enum GpuPreference {
-  PreferIntegratedGpu,
-  PreferDiscreteGpu
-};
-
-}  // namespace gfx
-
-#endif  // UI_GFX_GL_GPU_PREFERENCE_H_