Ensure that scheduled tasks are executed during db thread shutdown

Source/modules/webdatabase/DatabaseThread.cpp

 /*
  * Copyright (C) 2007, 2008, 2013 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 87 matching lines @@
     if (m_openDatabaseSet.size() > 0) {
         // As the call to close will modify the original set, we must take a copy to iterate over.
         DatabaseSet openSetCopy;
         openSetCopy.swap(m_openDatabaseSet);
         DatabaseSet::iterator end = openSetCopy.end();
         for (DatabaseSet::iterator it = openSetCopy.begin(); it != end; ++it)
             (*it).get()->close();
     }
 
     if (m_cleanupSync) // Someone wanted to know when we were done cleaning up.
-        m_cleanupSync->taskCompleted();
+        m_thread->postTask(new Task(WTF::bind(&DatabaseTaskSynchronizer::taskCompleted, m_cleanupSync)));
 }
 
 void DatabaseThread::recordDatabaseOpen(DatabaseBackend* database)
 {
     ASSERT(isDatabaseThread());
     ASSERT(database);
     ASSERT(!m_openDatabaseSet.contains(database));
     m_openDatabaseSet.add(database);
 }
 
@@ skipping 18 matching lines @@
 
 void DatabaseThread::scheduleTask(PassOwnPtr<DatabaseTask> task)
 {
     ASSERT(m_thread);
     ASSERT(!task->hasSynchronizer() || task->hasCheckedForTermination());
     // WebThread takes ownership of the task.
     m_thread->postTask(task.leakPtr());
 }
 
 } // namespace WebCore