Refactor the Heap into ThreadHeap to prepare for per thread heaps

third_party/WebKit/Source/modules/webdatabase/SQLTransactionBackend.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 339 matching lines @@
     , m_wrapper(wrapper)
     , m_hasCallback(m_frontend->hasCallback())
     , m_hasSuccessCallback(m_frontend->hasSuccessCallback())
     , m_hasErrorCallback(m_frontend->hasErrorCallback())
     , m_shouldRetryCurrentStatement(false)
     , m_modifiedDatabase(false)
     , m_lockAcquired(false)
     , m_readOnly(readOnly)
     , m_hasVersionMismatch(false)
 {
+    ASSERT(isMainThread());
     ASSERT(m_database);
     m_frontend->setBackend(this);
     m_requestedState = SQLTransactionState::AcquireLock;
 }
 
 SQLTransactionBackend::~SQLTransactionBackend()
 {
     ASSERT(!m_sqliteTransaction);
 }
 
@@ skipping 449 matching lines @@
 }
 
 SQLTransactionState SQLTransactionBackend::sendToFrontendState()
 {
     ASSERT(m_nextState != SQLTransactionState::Idle);
     m_frontend->requestTransitToState(m_nextState);
     return SQLTransactionState::Idle;
 }
 
 } // namespace blink