Ensure real GL Api is set before making GL calls.

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 177 matching lines @@
   }
   g_gl = NULL;
   g_current_gl_context = NULL;
   g_driver_gl.ClearBindings();
 }
 
 GLApi::GLApi() {
 }
 
 GLApi::~GLApi() {
+  if (GetCurrentGLApi() == this)
+    SetGLApi(NULL);
 }
 
 GLApiBase::GLApiBase()
     : driver_(NULL) {
 }
 
 GLApiBase::~GLApiBase() {
 }
 
 void GLApiBase::InitializeBase(DriverGL* driver) {
@@ skipping 96 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