Oilpan: Prepare to move AbstractSQLStatementBackend and SQLStatementBackend to Oilpan heap.

Source/modules/webdatabase/AbstractSQLStatementBackend.h

Index: Source/modules/webdatabase/AbstractSQLStatementBackend.h
diff --git a/Source/modules/webdatabase/AbstractSQLStatementBackend.h b/Source/modules/webdatabase/AbstractSQLStatementBackend.h
index 11a8c531d678a9afb59604888c23fdcc3c3321f7..3df2472e24e91b046c6fd2d494a579ba13a506a0 100644
--- a/Source/modules/webdatabase/AbstractSQLStatementBackend.h
+++ b/Source/modules/webdatabase/AbstractSQLStatementBackend.h
@@ -26,15 +26,17 @@
 #ifndef AbstractSQLStatementBackend_h
 #define AbstractSQLStatementBackend_h
 
+#include "heap/Handle.h"
 #include "modules/webdatabase/SQLError.h"
 #include "modules/webdatabase/SQLResultSet.h"
 #include "wtf/ThreadSafeRefCounted.h"
 
 namespace WebCore {
 
-class AbstractSQLStatementBackend : public ThreadSafeRefCounted<AbstractSQLStatementBackend> {
+class AbstractSQLStatementBackend : public ThreadSafeRefCountedWillBeGarbageCollectedFinalized<AbstractSQLStatementBackend> {
 public:
     virtual ~AbstractSQLStatementBackend() { }
+    virtual void trace(Visitor*) = 0;
 
     virtual PassRefPtr<SQLError> sqlError() const = 0;
     virtual PassRefPtr<SQLResultSet> sqlResultSet() const = 0;