Manage WebSQL callbacks with OwnPtr instead of refcounting

Source/modules/webdatabase/DatabaseCallback.h

Index: Source/modules/webdatabase/DatabaseCallback.h
diff --git a/Source/modules/webdatabase/DatabaseCallback.h b/Source/modules/webdatabase/DatabaseCallback.h
index e8b472c7b1b73f7749337ec22d30384188670eb4..f8834cb4e6f958f8db7cdfd1aa61cd63927a616f 100644
--- a/Source/modules/webdatabase/DatabaseCallback.h
+++ b/Source/modules/webdatabase/DatabaseCallback.h
@@ -31,14 +31,12 @@
 #ifndef DatabaseCallback_h
 #define DatabaseCallback_h
 
-#include "wtf/ThreadSafeRefCounted.h"
-
 namespace WebCore {
 
 class Database;
 class DatabaseSync;
 
-class DatabaseCallback : public ThreadSafeRefCounted<DatabaseCallback> {
+class DatabaseCallback {
 public:
     virtual ~DatabaseCallback() { }
     virtual bool handleEvent(Database*) = 0;