Revert of Enable per thread heap for database thread

third_party/WebKit/Source/modules/webdatabase/SQLTransactionCoordinator.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 32 matching lines @@
     return database->stringIdentifier();
 }
 
 SQLTransactionCoordinator::SQLTransactionCoordinator()
     : m_isShuttingDown(false)
 {
 }
 
 DEFINE_TRACE(SQLTransactionCoordinator)
 {
+    visitor->trace(m_coordinationInfoMap);
 }
 
 void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)
 {
     if (info.activeWriteTransaction || info.pendingTransactions.isEmpty())
         return;
 
     SQLTransactionBackend* firstPendingTransaction = info.pendingTransactions.first();
     if (firstPendingTransaction->isReadOnly()) {
         do {
@@ skipping 59 matching lines @@
     // Notify all transactions in progress that the database thread is shutting down
     for (CoordinationInfoHeapMap::iterator coordinationInfoIterator = m_coordinationInfoMap.begin();
          coordinationInfoIterator != m_coordinationInfoMap.end(); ++coordinationInfoIterator) {
         CoordinationInfo& info = coordinationInfoIterator->value;
 
         // Clean up transactions that have reached "lockAcquired":
         // Transaction phase 4 cleanup. See comment on "What happens if a
         // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
         if (info.activeWriteTransaction)
             info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();
-        for (auto& it : info.activeReadTransactions) {
-            it->notifyDatabaseThreadIsShuttingDown();
+        for (HeapHashSet<Member<SQLTransactionBackend>>::iterator activeReadTransactionsIterator =
+                     info.activeReadTransactions.begin();
+             activeReadTransactionsIterator != info.activeReadTransactions.end();
+             ++activeReadTransactionsIterator) {
+            (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();
         }
 
         // Clean up transactions that have NOT reached "lockAcquired":
         // Transaction phase 3 cleanup. See comment on "What happens if a
         // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
         while (!info.pendingTransactions.isEmpty()) {
             SQLTransactionBackend* transaction = info.pendingTransactions.takeFirst();
             transaction->notifyDatabaseThreadIsShuttingDown();
         }
     }
 
     // Clean up all pending transactions for all databases
     m_coordinationInfoMap.clear();
 }
 
 } // namespace blink