Don't create child window for WGL.

ui/gl/gl_surface_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_SURFACE_WGL_H_
 #define UI_GL_GL_SURFACE_WGL_H_
 
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gl/gl_surface.h"
 
@@ skipping 24 matching lines @@
   // Implement GLSurface.
   virtual bool Initialize();
   virtual void Destroy();
   virtual bool IsOffscreen();
   virtual bool SwapBuffers();
   virtual gfx::Size GetSize();
   virtual void* GetHandle();
 
  private:
   gfx::AcceleratedWidget window_;
-  gfx::AcceleratedWidget child_window_;
   HDC device_context_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeViewGLSurfaceWGL);
 };
 
 
 // A surface used to render to an offscreen pbuffer.
 class PbufferGLSurfaceWGL : public GLSurfaceWGL {
  public:
   explicit PbufferGLSurfaceWGL(const gfx::Size& size);
@@ skipping 11 matching lines @@
   gfx::Size size_;
   HDC device_context_;
   void* pbuffer_;
 
   DISALLOW_COPY_AND_ASSIGN(PbufferGLSurfaceWGL);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_SURFACE_WGL_H_