Convert SerialIoHandler to use buffer interfaces for I/O API methods.

extensions/browser/api/serial/serial_connection.h

Index: extensions/browser/api/serial/serial_connection.h
diff --git a/extensions/browser/api/serial/serial_connection.h b/extensions/browser/api/serial/serial_connection.h
index 0a00012666442816e5c0e2a41cb6b56d58bd7c93..638b89859cd5814155ba4f11201de6d85048b9c1 100644
--- a/extensions/browser/api/serial/serial_connection.h
+++ b/extensions/browser/api/serial/serial_connection.h
@@ -15,6 +15,7 @@
 #include "extensions/browser/api/api_resource.h"
 #include "extensions/browser/api/api_resource_manager.h"
 #include "extensions/common/api/serial.h"
+#include "net/base/io_buffer.h"
 
 using content::BrowserThread;
 
@@ -140,8 +141,7 @@ class SerialConnection : public ApiResource,
   void OnSendTimeout();
 
   // Receives read completion notification from the |io_handler_|.
-  void OnAsyncReadComplete(const std::string& data,
-                           device::serial::ReceiveError error);
+  void OnAsyncReadComplete(int bytes_read, device::serial::ReceiveError error);
 
   // Receives write completion notification from the |io_handler_|.
   void OnAsyncWriteComplete(int bytes_sent, device::serial::SendError error);
@@ -185,6 +185,8 @@ class SerialConnection : public ApiResource,
   // Send().
   scoped_ptr<TimeoutTask> send_timeout_task_;
 
+  scoped_refptr<net::IOBuffer> receive_buffer_;
+
   // Asynchronous I/O handler.
   scoped_refptr<device::SerialIoHandler> io_handler_;
 };