Unset GL Api when releasing a context.

ui/gl/gl_gl_api_implementation.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_gl_api_implementation.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 144 matching lines @@
     g_gl = g_trace_gl;
   }
   SetGLToRealGLApi();
 }
 
 GLApi* GetCurrentGLApi() {
   return g_current_gl_context;
 }
 
 void SetGLApi(GLApi* api) {
-  g_current_gl_context = api;
+  g_current_gl_context_tls.Pointer()->Set(api);
 }
 
 void SetGLToRealGLApi() {
   SetGLApi(g_gl);
 }
 
 void InitializeGLExtensionBindingsGL(GLContext* context) {
   g_driver_gl.InitializeExtensions(context);
 }
 
 void InitializeDebugGLBindingsGL() {
   g_driver_gl.InitializeDebugBindings();
 }
 
 void ClearGLBindingsGL() {
   if (g_real_gl) {
     delete g_real_gl;
     g_real_gl = NULL;
   }
   if (g_trace_gl) {
     delete g_trace_gl;
     g_trace_gl = NULL;
   }
   g_gl = NULL;
-  g_current_gl_context = NULL;
   g_driver_gl.ClearBindings();
 }
 
 GLApi::GLApi() {
 }
 
 GLApi::~GLApi() {
   if (GetCurrentGLApi() == this)
     SetGLApi(NULL);
 }
@@ skipping 105 matching lines @@
 const GLubyte* VirtualGLApi::glGetStringFn(GLenum name) {
   switch (name) {
     case GL_EXTENSIONS:
       return reinterpret_cast<const GLubyte*>(extensions_.c_str());
     default:
       return driver_->fn.glGetStringFn(name);
   }
 }
 
 }  // namespace gfx