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

ui/gl/gl_context_stub.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_STUB_H_
 #define UI_GL_GL_CONTEXT_STUB_H_
 
 #include "ui/gl/gl_context.h"
 
 namespace gfx {
 
 // A GLContext that does nothing for unit tests.
-class GL_EXPORT GLContextStub : public GLContext {
+class GL_EXPORT GLContextStub : public GLContextReal {
  public:
   GLContextStub();
 
   // Implement GLContext.
   virtual bool Initialize(GLSurface* compatible_surface,
                           GpuPreference gpu_preference) OVERRIDE;
   virtual void Destroy() OVERRIDE;
   virtual bool MakeCurrent(GLSurface* surface) OVERRIDE;
   virtual void ReleaseCurrent(GLSurface* surface) OVERRIDE;
   virtual bool IsCurrent(GLSurface* surface) OVERRIDE;
   virtual void* GetHandle() OVERRIDE;
   virtual void SetSwapInterval(int interval) OVERRIDE;
   virtual std::string GetExtensions() OVERRIDE;
 
  protected:
   virtual ~GLContextStub();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(GLContextStub);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_CONTEXT_STUB_H_