Make GL calls go through subclassable class.

ui/gl/gl_wgl_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_wgl_api_implementation.h"
+
+namespace gfx {
+
+RealWGLApi g_real_wgl;
+
+void InitializeGLBindingsWGL() {
+  g_driver_wgl.InitializeBindings();
+  g_real_wgl.Initialize(&g_driver_wgl);
+  g_current_wgl_context = &g_real_wgl;
+}
+
+void InitializeGLExtensionBindingsWGL(GLContext* context) {
+  g_driver_wgl.InitializeExtensionBindings(context);
+}
+
+void InitializeDebugGLBindingsWGL() {
+  g_driver_wgl.InitializeDebugBindings();
+}
+
+void ClearGLBindingsWGL() {
+  g_driver_wgl.ClearBindings();
+}
+
+WGLApi::WGLApi() {
+}
+
+WGLApi::~WGLApi() {
+}
+
+RealWGLApi::RealWGLApi() {
+}
+
+void RealWGLApi::Initialize(DriverWGL* driver) {
+  driver_ = driver;
+}
+
+}  // namespace gfx
+
+