[Oilpan] Apply RefCountedGarbageCollectedEventTarget on AbstractWorker

Source/web/ServiceWorkerGlobalScopeProxy.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 200 matching lines @@
     m_client.workerContextStarted(this);
 }
 
 void ServiceWorkerGlobalScopeProxy::workerGlobalScopeClosed()
 {
     m_document.postTask(FROM_HERE, createCrossThreadTask(&WebEmbeddedWorkerImpl::terminateWorkerContext, &m_embeddedWorker));
 }
 
 void ServiceWorkerGlobalScopeProxy::willDestroyWorkerGlobalScope()
 {
-    m_workerGlobalScope = 0;
+    m_workerGlobalScope = nullptr;
     m_client.willDestroyWorkerContext();
 }
 
 void ServiceWorkerGlobalScopeProxy::workerThreadTerminated()
 {
     m_client.workerContextDestroyed();
 }
 
 ServiceWorkerGlobalScopeProxy::ServiceWorkerGlobalScopeProxy(WebEmbeddedWorkerImpl& embeddedWorker, Document& document, WebServiceWorkerContextClient& client)
     : m_embeddedWorker(embeddedWorker)
     , m_document(document)
     , m_client(client)
-    , m_workerGlobalScope(0)
+    , m_workerGlobalScope(nullptr)
 {
 }
 
 } // namespace blink