GPU: Keep track of the last real context and real surface made current.

ui/gl/gl_context_glx.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_GLX_H_
 #define UI_GL_GL_CONTEXT_GLX_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_export.h"
 
 namespace gfx {
 
 class GLSurface;
 
 // Encapsulates a GLX OpenGL context.
-class GL_EXPORT GLContextGLX : public GLContext {
+class GL_EXPORT GLContextGLX : public GLContextReal {
  public:
   explicit GLContextGLX(GLShareGroup* share_group);
 
   Display* display();
 
   // Implement GLContext.
   virtual bool Initialize(
       GLSurface* compatible_surface, GpuPreference gpu_preference) OVERRIDE;
   virtual void Destroy() OVERRIDE;
   virtual bool MakeCurrent(GLSurface* surface) OVERRIDE;
@@ skipping 11 matching lines @@
  private:
   void* context_;
   Display* display_;
 
   DISALLOW_COPY_AND_ASSIGN(GLContextGLX);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_CONTEXT_GLX_H_