Reland: Add code to deal with serial device disconnection detection on Windows

device/serial/serial_io_handler.h

Index: device/serial/serial_io_handler.h
diff --git a/device/serial/serial_io_handler.h b/device/serial/serial_io_handler.h
index 81d70282a00188dce960ca65308b6d3e119707ce..c0fc3de577b1032b035253f9f19188d75e658ab9 100644
--- a/device/serial/serial_io_handler.h
+++ b/device/serial/serial_io_handler.h
@@ -190,6 +190,12 @@ class SerialIoHandler : public base::NonThreadSafe,
   // Possibly fixes up a serial port path name in a platform-specific manner.
   static std::string MaybeFixUpPortName(const std::string& port_name);
 
+  scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner_;
+  // On Chrome OS, PermissionBrokerClient should be called on the UI thread.
+  scoped_refptr<base::SingleThreadTaskRunner> ui_thread_task_runner_;
+
+  std::string port_;
+
  private:
   friend class base::RefCounted<SerialIoHandler>;
 
@@ -225,10 +231,6 @@ class SerialIoHandler : public base::NonThreadSafe,
   // Callback to handle the completion of a pending Open() request.
   OpenCompleteCallback open_complete_;
 
-  scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner_;
-  // On Chrome OS, PermissionBrokerClient should be called on the UI thread.
-  scoped_refptr<base::SingleThreadTaskRunner> ui_thread_task_runner_;
-
   DISALLOW_COPY_AND_ASSIGN(SerialIoHandler);
 };