C++11 declares a type safe null pointer

content/common/gpu/client/context_provider_command_buffer.cc

 // Copyright (c) 2013 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/context_provider_command_buffer.h"
 
 #include <set>
 #include <vector>
 
 #include "base/callback_helpers.h"
 #include "base/strings/stringprintf.h"
 #include "cc/output/managed_memory_policy.h"
 #include "gpu/command_buffer/client/gles2_implementation.h"
 #include "webkit/common/gpu/grcontext_for_webgraphicscontext3d.h"
 
 namespace content {
 
 class ContextProviderCommandBuffer::LostContextCallbackProxy
     : public blink::WebGraphicsContext3D::WebGraphicsContextLostCallback {
  public:
   explicit LostContextCallbackProxy(ContextProviderCommandBuffer* provider)
       : provider_(provider) {
     provider_->context3d_->setContextLostCallback(this);
   }
 
   virtual ~LostContextCallbackProxy() {
-    provider_->context3d_->setContextLostCallback(NULL);
+    provider_->context3d_->setContextLostCallback(nullptr);
   }
 
   virtual void onContextLost() {
     provider_->OnLostContext();
   }
 
  private:
   ContextProviderCommandBuffer* provider_;
 };
 
 scoped_refptr<ContextProviderCommandBuffer>
 ContextProviderCommandBuffer::Create(
     scoped_ptr<WebGraphicsContext3DCommandBufferImpl> context3d,
     const std::string& debug_name) {
   if (!context3d)
-    return NULL;
+    return nullptr;
 
   return new ContextProviderCommandBuffer(context3d.Pass(), debug_name);
 }
 
 ContextProviderCommandBuffer::ContextProviderCommandBuffer(
     scoped_ptr<WebGraphicsContext3DCommandBufferImpl> context3d,
     const std::string& debug_name)
     : context3d_(context3d.Pass()),
       debug_name_(debug_name),
       destroyed_(false) {
@@ skipping 160 matching lines @@
 
 void ContextProviderCommandBuffer::SetMemoryPolicyChangedCallback(
     const MemoryPolicyChangedCallback& memory_policy_changed_callback) {
   DCHECK(context_thread_checker_.CalledOnValidThread());
   DCHECK(memory_policy_changed_callback_.is_null() ||
          memory_policy_changed_callback.is_null());
   memory_policy_changed_callback_ = memory_policy_changed_callback;
 }
 
 }  // namespace content