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

device/serial/data_receiver.cc

Index: device/serial/data_receiver.cc
diff --git a/device/serial/data_receiver.cc b/device/serial/data_receiver.cc
index 2f238e317d31251155a900b76000b5a7b2cfecb8..fdc23caaff385c144b1f05ed7b25a5dabf4b0a4f 100644
--- a/device/serial/data_receiver.cc
+++ b/device/serial/data_receiver.cc
@@ -107,19 +107,16 @@
   bool dispatched;
 };
 
-DataReceiver::DataReceiver(
-    mojo::InterfacePtr<serial::DataSource> source,
-    mojo::InterfaceRequest<serial::DataSourceClient> client,
-    uint32_t buffer_size,
-    int32_t fatal_error_value)
+DataReceiver::DataReceiver(mojo::InterfacePtr<serial::DataSource> source,
+                           uint32_t buffer_size,
+                           int32_t fatal_error_value)
     : source_(source.Pass()),
-      client_(this, client.Pass()),
       fatal_error_value_(fatal_error_value),
       shut_down_(false),
       weak_factory_(this) {
+  source_.set_client(this);
   source_.set_error_handler(this);
   source_->Init(buffer_size);
-  client_.set_error_handler(this);
 }
 
 bool DataReceiver::Receive(const ReceiveDataCallback& callback,