Make GL calls go through subclassable class.

ui/gl/gl_bindings.h

 // 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.
 
 #ifndef UI_GL_GL_BINDINGS_H_
 #define UI_GL_GL_BINDINGS_H_
 
 // Includes the platform independent and platform dependent GL headers.
 // Only include this in cc files. It pulls in system headers, including
 // the X11 headers on linux, which define all kinds of macros that are
@@ skipping 78 matching lines @@
 #include "gl_bindings_autogen_wgl.h"
 #elif defined(USE_X11)
 #include "gl_bindings_autogen_egl.h"
 #include "gl_bindings_autogen_glx.h"
 #elif defined(OS_ANDROID)
 #include "gl_bindings_autogen_egl.h"
 #endif
 
 namespace gfx {
 
+GL_EXPORT extern GLApi* g_current_gl_context;
+GL_EXPORT extern OSMESAApi* g_current_osmesa_context;
+GL_EXPORT extern DriverGL g_driver_gl;
+GL_EXPORT extern DriverOSMESA g_driver_osmesa;
+
+#if defined(OS_WIN)
+
+GL_EXPORT extern EGLApi* g_current_egl_context;
+GL_EXPORT extern WGLApi* g_current_wgl_context;
+GL_EXPORT extern DriverEGL g_driver_egl;
+GL_EXPORT extern DriverWGL g_driver_wgl;
+
+#elif defined(USE_X11)
+
+GL_EXPORT extern EGLApi* g_current_egl_context;
+GL_EXPORT extern GLXApi* g_current_glx_context;
+GL_EXPORT extern DriverEGL g_driver_egl;
+GL_EXPORT extern DriverGLX g_driver_glx;
+
+#elif defined(OS_ANDROID)
+
+GL_EXPORT extern EGLApi* g_current_egl_context;
+GL_EXPORT extern DriverEGL g_driver_egl;
+
+#endif
+
 // Find an entry point to the mock GL implementation.
 void* GL_BINDING_CALL GetMockGLProcAddress(const char* name);
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_BINDINGS_H_