Make GL calls go through subclassable class.

ui/gl/gl_osmesa_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_osmesa_api_implementation.h"
+
+namespace gfx {
+
+RealOSMESAApi g_real_osmesa;
+
+void InitializeGLBindingsOSMESA() {
+  g_driver_osmesa.InitializeBindings();
+  g_real_osmesa.Initialize(&g_driver_osmesa);
+  g_current_osmesa_context = &g_real_osmesa;
+}
+
+void InitializeGLExtensionBindingsOSMESA(GLContext* context) {
+  g_driver_osmesa.InitializeExtensionBindings(context);
+}
+
+void InitializeDebugGLBindingsOSMESA() {
+  g_driver_osmesa.InitializeDebugBindings();
+}
+
+void ClearGLBindingsOSMESA() {
+  g_driver_osmesa.ClearBindings();
+}
+
+OSMESAApi::OSMESAApi() {
+}
+
+OSMESAApi::~OSMESAApi() {
+}
+
+RealOSMESAApi::RealOSMESAApi() {
+}
+
+void RealOSMESAApi::Initialize(DriverOSMESA* driver) {
+  driver_ = driver;
+}
+
+}  // namespace gfx
+
+