Don't try to set context callback if the context failed to be created.

content/renderer/render_thread_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/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <vector>
@@ skipping 775 matching lines @@
   }
 }
 
 WebGraphicsContext3DCommandBufferImpl*
 RenderThreadImpl::GetGpuVDAContext3D() {
   if (!gpu_vda_context3d_.get()) {
     gpu_vda_context3d_.reset(
         WebGraphicsContext3DCommandBufferImpl::CreateOffscreenContext(
             this, WebKit::WebGraphicsContext3D::Attributes(),
             GURL("chrome://gpu/RenderThreadImpl::GetGpuVDAContext3D")));
-    gpu_vda_context3d_->setContextLostCallback(context_lost_cb_.get());
+    if (gpu_vda_context3d_.get())
+      gpu_vda_context3d_->setContextLostCallback(context_lost_cb_.get());
   }
   return gpu_vda_context3d_.get();
 }
 
 content::AudioRendererMixerManager*
 RenderThreadImpl::GetAudioRendererMixerManager() {
   if (!audio_renderer_mixer_manager_.get()) {
     audio_renderer_mixer_manager_.reset(new AudioRendererMixerManager(
         audio_hardware::GetOutputSampleRate(),
         audio_hardware::GetOutputBufferSize()));
@@ skipping 263 matching lines @@
 
 scoped_refptr<base::MessageLoopProxy>
 RenderThreadImpl::GetFileThreadMessageLoopProxy() {
   DCHECK(message_loop() == MessageLoop::current());
   if (!file_thread_.get()) {
     file_thread_.reset(new base::Thread("Renderer::FILE"));
     file_thread_->Start();
   }
   return file_thread_->message_loop_proxy();
 }