Do not allocate depth-stencil buffers for GLSurfaces.

ui/gfx/gl/gl_surface_glx.cc

 // Copyright (c) 2011 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.
 
 extern "C" {
 #include <X11/Xlib.h>
 }
 
 #include "ui/gfx/gl/gl_surface_glx.h"
 
@@ skipping 196 matching lines @@
 
 bool PbufferGLSurfaceGLX::Initialize() {
   DCHECK(!pbuffer_);
 
   static const int config_attributes[] = {
     GLX_BUFFER_SIZE, 32,
     GLX_ALPHA_SIZE, 8,
     GLX_BLUE_SIZE, 8,
     GLX_GREEN_SIZE, 8,
     GLX_RED_SIZE, 8,
-    GLX_DEPTH_SIZE, 16,  // TODO(apatrick): support optional depth buffer
-    GLX_STENCIL_SIZE, 8,
     GLX_RENDER_TYPE, GLX_RGBA_BIT,
     GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
     GLX_DOUBLEBUFFER, False,
     0
   };
 
   int num_elements = 0;
   scoped_ptr_malloc<GLXFBConfig, ScopedPtrXFree> configs(
       glXChooseFBConfig(g_display,
                         DefaultScreen(g_display),
@@ skipping 51 matching lines @@
 
 void* PbufferGLSurfaceGLX::GetHandle() {
   return reinterpret_cast<void*>(pbuffer_);
 }
 
 void* PbufferGLSurfaceGLX::GetConfig() {
   return config_;
 }
 
 }  // namespace gfx