remove hlo op flow used in MPMD

PiperOrigin-RevId: 433506757
diff --git a/tensorflow/core/profiler/convert/op_stats_combiner.cc b/tensorflow/core/profiler/convert/op_stats_combiner.cc
index 5410335..f0d1ed6 100644
--- a/tensorflow/core/profiler/convert/op_stats_combiner.cc
+++ b/tensorflow/core/profiler/convert/op_stats_combiner.cc
@@ -56,8 +56,6 @@
     hlo_metrics_db_complete_steps_only_combiner->Combine(src.hlo_metrics_db());
   }
   hlo_metrics_db_per_step_combiner->Combine(src.hlo_metrics_db());
-  CombineCoreIdMap(src_host_id, src.flow_db_per_core(),
-                   dst->mutable_flow_db_per_core());
   CombineCoreIdMap(src_host_id, src.all_reduce_db_per_core(),
                    dst->mutable_all_reduce_db_per_core());
   CombineCoreIdMap(src_host_id, src.core_id_to_replica_id_map(),
diff --git a/tensorflow/core/profiler/protobuf/steps_db.proto b/tensorflow/core/profiler/protobuf/steps_db.proto
index 47da701..583d9b3 100644
--- a/tensorflow/core/profiler/protobuf/steps_db.proto
+++ b/tensorflow/core/profiler/protobuf/steps_db.proto
@@ -37,32 +37,6 @@
   google.protobuf.Any step_breakdown = 4;
 }
 
-// Result proto for metrics on flow events.
-message FlowEventInfo {
-  // Unique id for each send and recv pair.
-  uint64 flow_id = 1;
-  // Channel id generated by the XLA compiler, it is statically unique within an
-  // HloModule.
-  int64 channel_id = 2;
-  // The name of the hlo op.
-  string name = 3;
-  // Category of the hlo op.
-  string category = 4;
-  // The start time in picoseconds of the op event.
-  uint64 start_time_ps = 5;
-  // The end time in picoseconds of the op event.
-  uint64 end_time_ps = 6;
-  // The size of the op in bytes.
-  uint64 byte_size = 7;
-  // The replica id of the program running the flow event.
-  uint32 replica_id = 8;
-}
-
-// Result database for core to core flow events.
-message FlowDbResult {
-  repeated FlowEventInfo flow_info = 1;
-}
-
 // Result proto for all -educe ops.
 message AllReduceInfo {
   // Unique id for all-reduce ops.
@@ -94,8 +68,6 @@
   map<uint32, StepInfoResult> step_info_per_core = 2;
   // The result for the per-step HLO-metric database.
   OpMetricsDb hlo_metrics_db = 3;
-  // The result for send and recv flows.
-  map<uint32, FlowDbResult> flow_db_per_core = 4;
   // A map from core ID to program replica id. Replica id map could change
   // during a profile session, but should stay stable within a step.
   map<uint32, uint32> core_id_to_replica_id_map = 5;
@@ -107,6 +79,8 @@
   // 2. DeviceToHost
   // 3. DeviceToDevice
   repeated DeviceMemoryTransfer device_memory_transfers = 7;
+
+  reserved 4;
 }
 
 // Result proto for a StepDatabase.