Make GL calls go through subclassable class.

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"
+
+namespace gfx {
+
+RealGLApi g_real_gl;
+
+void InitializeGLBindingsGL() {
+  g_driver_gl.InitializeBindings();
+  g_real_gl.Initialize(&g_driver_gl);
+  g_current_gl_context = &g_real_gl;
+}
+
+void InitializeGLExtensionBindingsGL(GLContext* context) {
+  g_driver_gl.InitializeExtensionBindings(context);
+}
+
+void InitializeDebugGLBindingsGL() {
+  g_driver_gl.InitializeDebugBindings();
+}
+
+void ClearGLBindingsGL() {
+  g_driver_gl.ClearBindings();
+}
+
+GLApi::GLApi() {
+}
+
+GLApi::~GLApi() {
+}
+
+RealGLApi::RealGLApi() {
+}
+
+void RealGLApi::Initialize(DriverGL* driver) {
+  driver_ = driver;
+}
+
+}  // namespace gfx
+
+