Remove windows/mac/ios specific code from //ui

ui/gl/gl_context_cgl.h

-// Copyright (c) 2012 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_GL_GL_CONTEXT_CGL_H_
-#define UI_GL_GL_CONTEXT_CGL_H_
-
-#include <OpenGL/CGLTypes.h>
-
-#include "ui/gl/gl_context.h"
-
-namespace gfx {
-
-class GLSurface;
-
-// Encapsulates a CGL OpenGL context.
-class GLContextCGL : public GLContextReal {
- public:
-  explicit GLContextCGL(GLShareGroup* share_group);
-
-  // Implement GLContext.
-  bool Initialize(GLSurface* compatible_surface,
-                  GpuPreference gpu_preference) override;
-  void Destroy() override;
-  bool MakeCurrent(GLSurface* surface) override;
-  void ReleaseCurrent(GLSurface* surface) override;
-  bool IsCurrent(GLSurface* surface) override;
-  void* GetHandle() override;
-  void OnSetSwapInterval(int interval) override;
-  bool GetTotalGpuMemory(size_t* bytes) override;
-  void SetSafeToForceGpuSwitch() override;
-  bool ForceGpuSwitchIfNeeded() override;
-
- protected:
-  ~GLContextCGL() override;
-
- private:
-  GpuPreference GetGpuPreference();
-
-  void* context_;
-  GpuPreference gpu_preference_;
-
-  CGLPixelFormatObj discrete_pixelformat_;
-
-  int screen_;
-  int renderer_id_;
-  bool safe_to_force_gpu_switch_;
-
-  DISALLOW_COPY_AND_ASSIGN(GLContextCGL);
-};
-
-}  // namespace gfx
-
-#endif  // UI_GL_GL_CONTEXT_CGL_H_