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

ui/gl/gl_context_stub.cc

 // 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.
 
 #include "ui/gl/gl_context_stub.h"
 
 namespace gfx {
 
-GLContextStub::GLContextStub() : GLContext(NULL) {}
+GLContextStub::GLContextStub() : GLContextReal(NULL) {}
 
 bool GLContextStub::Initialize(
     GLSurface* compatible_surface, GpuPreference gpu_preference) {
   return true;
 }
 
 void GLContextStub::Destroy() {}
 
 bool GLContextStub::MakeCurrent(GLSurface* surface) {
-  SetCurrent(this, surface);
+  SetCurrent(surface);
   SetRealGLApi();
   return true;
 }
 
 void GLContextStub::ReleaseCurrent(GLSurface* surface) {
+  SetCurrent(NULL);
 }
 
 bool GLContextStub::IsCurrent(GLSurface* surface) {
   return true;
 }
 
 void* GLContextStub::GetHandle() {
   return NULL;
 }
 
 void GLContextStub::SetSwapInterval(int interval) {
 }
 
 std::string GLContextStub::GetExtensions() {
   return std::string();
 }
 
 GLContextStub::~GLContextStub() {}
 
 }  // namespace gfx