Oilpan: Prepare to move DatabaseContext to Oilpan heap.

Source/modules/webdatabase/Database.h

 /*
  * 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 68 matching lines @@
 
     void runTransaction(PassOwnPtr<SQLTransactionCallback>, PassOwnPtr<SQLTransactionErrorCallback>,
         PassOwnPtr<VoidCallback> successCallback, bool readOnly, const ChangeVersionData* = 0);
 
     Vector<String> performGetTableNames();
 
     void reportStartTransactionResult(int errorSite, int webSqlErrorCode, int sqliteErrorCode);
     void reportCommitTransactionResult(int errorSite, int webSqlErrorCode, int sqliteErrorCode);
 
     RefPtr<SecurityOrigin> m_databaseThreadSecurityOrigin;
-    RefPtr<DatabaseContext> m_databaseContext;
+    RefPtrWillBeMember<DatabaseContext> m_databaseContext;
 
     friend class DatabaseManager;
     friend class DatabaseServer; // FIXME: remove this when the backend has been split out.
     friend class DatabaseBackend; // FIXME: remove this when the backend has been split out.
     friend class SQLStatement;
     friend class SQLTransaction;
 };
 
 } // namespace WebCore
 
 #endif // Database_h