Revert of Remove Client= from device/serial/data_stream.mojom.

device/serial/data_stream_serialization.mojom

Index: device/serial/data_stream_serialization.mojom
diff --git a/device/serial/data_stream_serialization.mojom b/device/serial/data_stream_serialization.mojom
index de580d3e01b34f89b6cc15fb6a7b9967d883e464..259be286061fdf1be02b4c0ba80387deed0d34e9 100644
--- a/device/serial/data_stream_serialization.mojom
+++ b/device/serial/data_stream_serialization.mojom
@@ -10,8 +10,6 @@
 struct SerializedDataSender {
   // The control channel to the DataSink to which this DataSender sends data.
   DataSink sink;
-  // DataSinkClient&
-  handle<message_pipe> sink_client;
 
   // The error to report for sends in progress when a fatal error occurs.
   int32 fatal_error_value;
@@ -34,8 +32,6 @@
   // The control channel to the DataSource from which this DataReceiver receives
   // data.
   DataSource source;
-  // DataSourceClient&
-  handle<message_pipe> source_client;
 
   // The error to report for a receive in progress when a fatal error occurs.
   int32 fatal_error_value;