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

device/serial/data_sender.cc

Index: device/serial/data_sender.cc
diff --git a/device/serial/data_sender.cc b/device/serial/data_sender.cc
index bea8eb85c1a5cc3e81678595b4cc2dc717550543..18b1a43ef3357543a32a99bd16d95843262e0a35 100644
--- a/device/serial/data_sender.cc
+++ b/device/serial/data_sender.cc
@@ -62,17 +62,15 @@
 };
 
 DataSender::DataSender(mojo::InterfacePtr<serial::DataSink> sink,
-                       mojo::InterfaceRequest<serial::DataSinkClient> client,
                        uint32_t buffer_size,
                        int32_t fatal_error_value)
     : sink_(sink.Pass()),
-      client_(this, client.Pass()),
       fatal_error_value_(fatal_error_value),
       available_buffer_capacity_(buffer_size),
       shut_down_(false) {
   sink_.set_error_handler(this);
+  sink_.set_client(this);
   sink_->Init(buffer_size);
-  client_.set_error_handler(this);
 }
 
 DataSender::~DataSender() {