Manage WebSQL callbacks with OwnPtr instead of refcounting

Source/modules/webdatabase/SQLTransactionBackendSync.cpp

 /*
  * Copyright (C) 2010 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 33 matching lines @@
 #include "modules/webdatabase/SQLResultSet.h"
 #include "modules/webdatabase/SQLStatementSync.h"
 #include "modules/webdatabase/SQLTransactionClient.h"
 #include "modules/webdatabase/SQLTransactionSync.h"
 #include "modules/webdatabase/SQLTransactionSyncCallback.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
 
 namespace WebCore {
 
-SQLTransactionBackendSync::SQLTransactionBackendSync(DatabaseSync* db, PassRefPtr<SQLTransactionSyncCallback> callback, bool readOnly)
+SQLTransactionBackendSync::SQLTransactionBackendSync(DatabaseSync* db, PassOwnPtr<SQLTransactionSyncCallback> callback, bool readOnly)
     : m_database(db)
     , m_callback(callback)
     , m_readOnly(readOnly)
     , m_hasVersionMismatch(false)
     , m_modifiedDatabase(false)
     , m_transactionClient(adoptPtr(new SQLTransactionClient()))
 {
     ASSERT(m_database->executionContext()->isContextThread());
 }
 
@@ skipping 111 matching lines @@
     m_hasVersionMismatch = !m_database->expectedVersion().isEmpty() && (m_database->expectedVersion() != actualVersion);
     m_database->reportStartTransactionResult(0, -1, 0); // OK
 }
 
 void SQLTransactionBackendSync::execute(ExceptionState& exceptionState)
 {
     ASSERT(m_database->executionContext()->isContextThread());
     if (!m_database->opened() || (m_callback && !m_callback->handleEvent(SQLTransactionSync::from(this)))) {
         if (m_database->lastErrorMessage().isEmpty())
             m_database->setLastErrorMessage("failed to execute transaction callback");
-        m_callback = 0;
+        m_callback.clear();
         exceptionState.throwDOMException(UnknownError, SQLError::unknownErrorMessage);
         return;
     }
 
-    m_callback = 0;
+    m_callback.clear();
 }
 
 void SQLTransactionBackendSync::commit(ExceptionState& exceptionState)
 {
     ASSERT(m_database->executionContext()->isContextThread());
     if (!m_database->opened()) {
         m_database->reportCommitTransactionResult(1, SQLError::UNKNOWN_ERR, 0);
         m_database->setLastErrorMessage("unable to commit transaction because the database is not open.");
         exceptionState.throwDOMException(UnknownError, SQLError::unknownErrorMessage);
         return;
@@ skipping 34 matching lines @@
     if (m_sqliteTransaction) {
         m_sqliteTransaction->rollback();
         m_sqliteTransaction.clear();
     }
     m_database->enableAuthorizer();
 
     ASSERT(!m_database->sqliteDatabase().transactionInProgress());
 }
 
 } // namespace WebCore