Fix lifecycle-vs-threads of GpuVDAContext3D.

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.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 "content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h"
 
 #include "third_party/khronos/GLES2/gl2.h"
 #ifndef GL_GLEXT_PROTOTYPES
 #define GL_GLEXT_PROTOTYPES 1
 #endif
@@ skipping 1407 matching lines @@
             allocation.suggest_have_backbuffer));
 }
 
 void WebGraphicsContext3DCommandBufferImpl::setErrorMessageCallback(
     WebGraphicsContext3D::WebGraphicsErrorMessageCallback* cb) {
   error_message_callback_ = cb;
 }
 
 void WebGraphicsContext3DCommandBufferImpl::setContextLostCallback(
     WebGraphicsContext3D::WebGraphicsContextLostCallback* cb) {
+  DCHECK(!context_lost_callback_ || !cb);

[piman, 2012/08/13 17:23:35]

why?

[Ami GONE FROM CHROMIUM, 2012/08/13 17:38:16]

Vestigial; was there to make sure my use of sCLC wasn't clobbering another use. 
Gone.

   context_lost_callback_ = cb;
 }
 
 WGC3Denum WebGraphicsContext3DCommandBufferImpl::getGraphicsResetStatusARB() {
   if (IsCommandBufferContextLost() &&
       context_lost_reason_ == GL_NO_ERROR) {
     return GL_UNKNOWN_CONTEXT_RESET_ARB;
   }
 
   return context_lost_reason_;
@@ skipping 129 matching lines @@
     swap_client_->OnViewContextSwapBuffersAborted();
 }
 
 void WebGraphicsContext3DCommandBufferImpl::OnErrorMessage(
     const std::string& message, int id) {
   if (error_message_callback_) {
     WebKit::WebString str = WebKit::WebString::fromUTF8(message.c_str());
     error_message_callback_->onErrorMessage(str, id);
   }
 }