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

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 73 matching lines @@
 void DatabaseThread::requestTermination(TaskSynchronizer *cleanupSync)
 {
     MutexLocker lock(m_terminationRequestedMutex);
     ASSERT(!m_terminationRequested);
     m_terminationRequested = true;
     m_cleanupSync = cleanupSync;
     WTF_LOG(StorageAPI, "DatabaseThread %p was asked to terminate\n", this);
     m_thread->postTask(new Task(WTF::bind(&DatabaseThread::cleanupDatabaseThread, this)));
 }
 
-bool DatabaseThread::terminationRequested() const
+bool DatabaseThread::terminationRequested(TaskSynchronizer* taskSynchronizer) const
 {
+#if ENABLE(ASSERT)
+    if (taskSynchronizer)
+        taskSynchronizer->setHasCheckedForTermination();
+#endif
+
     MutexLocker lock(m_terminationRequestedMutex);
     return m_terminationRequested;
 }
 
 void DatabaseThread::cleanupDatabaseThread()
 {
     WTF_LOG(StorageAPI, "Cleaning up DatabaseThread %p", this);
 
     // Clean up the list of all pending transactions on this database thread
     m_transactionCoordinator->shutdown();
@@ skipping 39 matching lines @@
 {
     ASSERT(isDatabaseThread());
     ASSERT(database);
     MutexLocker lock(m_terminationRequestedMutex);
     return !m_terminationRequested && m_openDatabaseSet.contains(database);
 }
 
 void DatabaseThread::scheduleTask(PassOwnPtr<DatabaseTask> task)
 {
     ASSERT(m_thread);
-    ASSERT(!terminationRequested());
+    ASSERT(!task->hasSynchronizer() || task->hasCheckedForTermination());
     // WebThread takes ownership of the task.
     m_thread->postTask(task.leakPtr());
 }
 
 } // namespace blink