899139bc_for_Tracing_in_SQL_Server_2014__Description
[Package name] XtpEngine [Event name] trace_flush_io_operation_for_delta_file [Description] 
This trace is trying to catch pages issued for flush that didn't make it to the file, or were lacking the correct DeltaWatermark Timestamp.
New Extended Events for Tracing in SQL Server 2014
Description