Revert of DatabaseBackend should not post a task to an already terminated database thread

Source/modules/webdatabase/DatabaseThread.h

 /*
  * Copyright (C) 2007, 2008 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 41 matching lines @@
 class TaskSynchronizer;
 
 class DatabaseThread : public ThreadSafeRefCountedWillBeGarbageCollectedFinalized<DatabaseThread> {
 public:
     static PassRefPtrWillBeRawPtr<DatabaseThread> create() { return adoptRefWillBeNoop(new DatabaseThread); }
     ~DatabaseThread();
     void trace(Visitor*);
 
     void start();
     void requestTermination(TaskSynchronizer* cleanupSync);
-    bool terminationRequested() const;
+    bool terminationRequested(TaskSynchronizer* = 0) const;
 
     void scheduleTask(PassOwnPtr<DatabaseTask>);
 
     void recordDatabaseOpen(Database*);
     void recordDatabaseClosed(Database*);
     bool isDatabaseOpen(Database*);
 
     bool isDatabaseThread() { return m_thread && m_thread->isCurrentThread(); }
 
     SQLTransactionClient* transactionClient() { return m_transactionClient.get(); }
@@ skipping 17 matching lines @@
     OwnPtrWillBeMember<SQLTransactionCoordinator> m_transactionCoordinator;
     TaskSynchronizer* m_cleanupSync;
 
     mutable Mutex m_terminationRequestedMutex;
     bool m_terminationRequested;
 };
 
 } // namespace blink
 
 #endif // DatabaseThread_h