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

ui/gl/gl_context_wgl.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_WGL_H_
-#define UI_GL_GL_CONTEXT_WGL_H_
-
-#include <string>
-
-#include "ui/gfx/native_widget_types.h"
-#include "ui/gl/gl_context.h"
-
-namespace gfx {
-
-class GLSurface;
-
-// This class is a wrapper around a GL context.
-class GLContextWGL : public GLContextReal {
- public:
-  explicit GLContextWGL(GLShareGroup* share_group);
-  virtual ~GLContextWGL();
-
-  // Implement GLContext.
-  virtual bool Initialize(
-      GLSurface* compatible_surface, GpuPreference gpu_preference);
-  virtual void Destroy();
-  virtual bool MakeCurrent(GLSurface* surface);
-  virtual void ReleaseCurrent(GLSurface* surface);
-  virtual bool IsCurrent(GLSurface* surface);
-  virtual void* GetHandle();
-  virtual void OnSetSwapInterval(int interval);
-  virtual std::string GetExtensions();
-
- private:
-  HGLRC context_;
-
-  DISALLOW_COPY_AND_ASSIGN(GLContextWGL);
-};
-
-}  // namespace gfx
-
-#endif  // UI_GL_GL_CONTEXT_WGL_H_