Fix GL error occuring on pbuffer surface.

gpu/command_buffer/service/gles2_cmd_decoder.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 "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 2719 matching lines @@
     DoBindFramebuffer(GL_FRAMEBUFFER, 0);
   } else {
     glBindFramebufferEXT(GL_FRAMEBUFFER, GetBackbufferServiceId());
     // These are NOT if the back buffer has these proprorties. They are
     // if we want the command buffer to enforce them regardless of what
     // the real backbuffer is assuming the real back buffer gives us more than
     // we ask for. In other words, if we ask for RGB and we get RGBA then we'll
     // make it appear RGB. If on the other hand we ask for RGBA nd get RGB we
     // can't do anything about that.
 
-    if (!surfaceless_) {
+    if (!surfaceless_ && !surface_->IsOffscreen()) {
       GLint alpha_bits = 0;
       GLint depth_bits = 0;
       GLint stencil_bits = 0;
 
       bool default_fb = (GetBackbufferServiceId() == 0);
 
       if (feature_info_->gl_version_info().is_desktop_core_profile) {
         glGetFramebufferAttachmentParameterivEXT(
             GL_FRAMEBUFFER,
             default_fb ? GL_BACK_LEFT : GL_COLOR_ATTACHMENT0,
@@ skipping 9870 matching lines @@
   }
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu