Privatize StrongBinding lifetime management

device/serial/serial_connection.h

Index: device/serial/serial_connection.h
diff --git a/device/serial/serial_connection.h b/device/serial/serial_connection.h
index a0e2a80171767a2ddaea482a2afb9f9fdafab483..c12a4339588bd5cfefbe4995c87a4be6e98738e2 100644
--- a/device/serial/serial_connection.h
+++ b/device/serial/serial_connection.h
@@ -12,7 +12,6 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "device/serial/serial.mojom.h"
-#include "mojo/public/cpp/bindings/strong_binding.h"
 
 namespace device {
 
@@ -27,8 +26,7 @@ class SerialConnection : public serial::Connection {
   SerialConnection(scoped_refptr<SerialIoHandler> io_handler,
                    mojo::InterfaceRequest<serial::DataSink> sink,
                    mojo::InterfaceRequest<serial::DataSource> source,
-                   mojo::InterfacePtr<serial::DataSourceClient> source_client,
-                   mojo::InterfaceRequest<serial::Connection> request);
+                   mojo::InterfacePtr<serial::DataSourceClient> source_client);
   ~SerialConnection() override;
 
   // serial::Connection overrides.
@@ -49,8 +47,6 @@ class SerialConnection : public serial::Connection {
   scoped_refptr<DataSinkReceiver> receiver_;
   scoped_refptr<DataSourceSender> sender_;
 
-  mojo::StrongBinding<serial::Connection> binding_;
-
   DISALLOW_COPY_AND_ASSIGN(SerialConnection);
 };