Oilpan: Prepare to move DatabaseContext to Oilpan heap.

Source/modules/webdatabase/Database.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 67 matching lines @@
 
     ASSERT(m_databaseContext->databaseThread());
 }
 
 Database::~Database()
 {
 }
 
 void Database::trace(Visitor* visitor)
 {
+    visitor->trace(m_databaseContext);
     DatabaseBackend::trace(visitor);
 }
 
 Database* Database::from(DatabaseBackend* backend)
 {
     return static_cast<Database*>(backend->m_frontend);
 }
 
 PassRefPtrWillBeRawPtr<DatabaseBackend> Database::backend()
 {
@@ skipping 145 matching lines @@
     backend()->reportStartTransactionResult(errorSite, webSqlErrorCode, sqliteErrorCode);
 }
 
 void Database::reportCommitTransactionResult(int errorSite, int webSqlErrorCode, int sqliteErrorCode)
 {
     backend()->reportCommitTransactionResult(errorSite, webSqlErrorCode, sqliteErrorCode);
 }
 
 
 } // namespace WebCore