Plumb through EGL_NV_post_sub_buffer and GLX_MESA_copy_sub_buffer.

gpu/command_buffer/service/feature_info.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.
 
 #include <set>
 #include <string>
 #include "gpu/command_buffer/service/feature_info.h"
 #include "gpu/command_buffer/service/gl_utils.h"
 #include "ui/gfx/gl/gl_implementation.h"
+#include "ui/gfx/gl/gl_surface.h"
 
 namespace gpu {
 namespace gles2 {
 
 FeatureInfo::FeatureInfo() {
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
@@ skipping 330 matching lines @@
   }
 
   // TODO(gman): Add support for these extensions.
   //     GL_OES_depth32
   //     GL_OES_element_index_uint
 
   feature_flags_.enable_texture_float_linear = enable_texture_float_linear;
   feature_flags_.enable_texture_half_float_linear =
       enable_texture_half_float_linear;
   feature_flags_.npot_ok = npot_ok;
+
+  if (ext.Desire("GL_CHROMIUM_post_sub_buffer") &&
+      gfx::GLSurface::GetCurrent() &&
+      gfx::GLSurface::GetCurrent()->SupportsPostSubBuffer()) {
+    AddExtensionString("GL_CHROMIUM_post_sub_buffer");
+  }
 }
 
 void FeatureInfo::AddExtensionString(const std::string& str) {
   if (extensions_.find(str) == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 }  // namespace gles2
 }  // namespace gpu