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

device/serial/data_receiver.h

Index: device/serial/data_receiver.h
diff --git a/device/serial/data_receiver.h b/device/serial/data_receiver.h
index 95be6402085adc8cc7d9808713278dcc295642d8..942bb5ced83902d4e077175708644ffa882f6748 100644
--- a/device/serial/data_receiver.h
+++ b/device/serial/data_receiver.h
@@ -29,7 +29,6 @@
   // size of |buffer_size|, with connection errors reported as
   // |fatal_error_value|.
   DataReceiver(mojo::InterfacePtr<serial::DataSource> source,
-               mojo::InterfaceRequest<serial::DataSourceClient> client,
                uint32_t buffer_size,
                int32_t fatal_error_value);
 
@@ -73,7 +72,6 @@
 
   // The control connection to the data source.
   mojo::InterfacePtr<serial::DataSource> source_;
-  mojo::Binding<serial::DataSourceClient> client_;
 
   // The error value to report in the event of a fatal error.
   const int32_t fatal_error_value_;