Fix for surfaceless implementation

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 2670 matching lines @@
 
   bool call_gl_clear = true;
 #if defined(OS_ANDROID)
   // Temporary workaround for Android WebView because this clear ignores the
   // clip and corrupts that external UI of the App. Not calling glClear is ok
   // because the system already clears the buffer before each draw. Proper
   // fix might be setting the scissor clip properly before initialize. See
   // crbug.com/259023 for details.
   call_gl_clear = surface_->GetHandle();
 #endif
-  if (call_gl_clear) {
+  // It is possible for us to not have a framebuffer at this point. If we don't
+  // then clearing will only generate an error.
+  if (call_gl_clear &&
+      glCheckFramebufferStatusEXT(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE) {
     // Clear the backbuffer.
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
   }
 
   supports_post_sub_buffer_ = surface->SupportsPostSubBuffer();
   if (feature_info_->workarounds()
           .disable_post_sub_buffers_for_onscreen_surfaces &&
       !surface->IsOffscreen())
     supports_post_sub_buffer_ = false;
 
@@ skipping 8573 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