Refactor GL bindings so there is no global GLApi or DriverGL.

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 gl {
 
-RealOSMESAApi* g_real_osmesa;
+RealOSMESAApi* g_real_osmesa = nullptr;
+DebugOSMESAApi* g_debug_osmesa = nullptr;
 
 void InitializeStaticGLBindingsOSMESA() {
   g_driver_osmesa.InitializeStaticBindings();
   if (!g_real_osmesa) {
     g_real_osmesa = new RealOSMESAApi();
   }
   g_real_osmesa->Initialize(&g_driver_osmesa);
   g_current_osmesa_context = g_real_osmesa;
   g_driver_osmesa.InitializeExtensionBindings();
 }
 
 void InitializeDebugGLBindingsOSMESA() {
-  g_driver_osmesa.InitializeDebugBindings();
+  if (!g_debug_osmesa) {
+    g_debug_osmesa = new DebugOSMESAApi(g_real_osmesa);
+  }
+  g_current_osmesa_context = g_debug_osmesa;
 }
 
 void ClearBindingsOSMESA() {
+  if (g_debug_osmesa) {
+    delete g_debug_osmesa;
+    g_debug_osmesa = NULL;
+  }
   if (g_real_osmesa) {
     delete g_real_osmesa;
     g_real_osmesa = NULL;
   }
   g_current_osmesa_context = NULL;
   g_driver_osmesa.ClearBindings();
 }
 
 OSMESAApi::OSMESAApi() {
 }
@@ skipping 15 matching lines @@
 RealOSMESAApi::RealOSMESAApi() {
 }
 
 RealOSMESAApi::~RealOSMESAApi() {
 }
 
 void RealOSMESAApi::Initialize(DriverOSMESA* driver) {
   InitializeBase(driver);
 }
 
+DebugOSMESAApi::DebugOSMESAApi(OSMESAApi* osmesa_api)
+    : osmesa_api_(osmesa_api) {}
+DebugOSMESAApi::~DebugOSMESAApi() {}
+
 TraceOSMESAApi::~TraceOSMESAApi() {
 }
 
 }  // namespace gl