Revert of Remove the concept of a cleanup task

Source/platform/WebThreadSupportingGC.h

 // Copyright 2014 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.
 
 #ifndef WebThreadSupportingGC_h
 #define WebThreadSupportingGC_h
 
 #include "platform/heap/glue/MessageLoopInterruptor.h"
 #include "platform/heap/glue/PendingGCRunner.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebThread.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
 // WebThreadSupportingGC wraps a WebThread and adds support for attaching
-// to and detaching from the Blink GC infrastructure. The initialize method
+// to and detaching from the Blink GC infrastructure. The attachGC method
 // must be called during initialization on the WebThread and before the
-// thread allocates any objects managed by the Blink GC. The shutdown
+// thread allocates any objects managed by the Blink GC. The detach GC
 // method must be called on the WebThread during shutdown when the thread
 // no longer needs to access objects managed by the Blink GC.
 class PLATFORM_EXPORT WebThreadSupportingGC final {
     WTF_MAKE_NONCOPYABLE(WebThreadSupportingGC);
 public:
     static PassOwnPtr<WebThreadSupportingGC> create(const char*);
     ~WebThreadSupportingGC();
 
     void postTask(const WebTraceLocation& location, WebThread::Task* task)
     {
@@ skipping 13 matching lines @@
     void addTaskObserver(WebThread::TaskObserver* observer)
     {
         m_thread->addTaskObserver(observer);
     }
 
     void removeTaskObserver(WebThread::TaskObserver* observer)
     {
         m_thread->removeTaskObserver(observer);
     }
 
-    void initialize();
-    void shutdown();
+    void attachGC();
+    void detachGC();
 
     WebThread& platformThread() const
     {
         ASSERT(m_thread);
         return *m_thread;
     }
 
 private:
     explicit WebThreadSupportingGC(const char*);
 
     OwnPtr<PendingGCRunner> m_pendingGCRunner;
     OwnPtr<MessageLoopInterruptor> m_messageLoopInterruptor;
 
     // FIXME: This has to be last because of crbug.com/401397.
     // A WorkerThread might get deleted before it had a chance to properly
     // shut down. By deleting the WebThread first, we can guarantee that
     // no pending tasks on the thread might want to access any of the other
     // members during the WorkerThread's destruction.
     OwnPtr<WebThread> m_thread;
 };
 
 }
 
 #endif