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

device/serial/serial_io_handler.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DEVICE_SERIAL_SERIAL_IO_HANDLER_H_
 #define DEVICE_SERIAL_SERIAL_IO_HANDLER_H_
 
 #include "base/callback.h"
 #include "base/files/file.h"
 #include "base/memory/ref_counted.h"
@@ skipping 172 matching lines @@
 
   serial::SendError write_cancel_reason() const { return write_cancel_reason_; }
 
   bool write_canceled() const { return write_canceled_; }
 
   const serial::ConnectionOptions& options() const { return options_; }
 
   // 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_;

[grt (UTC plus 2), 2015/11/13 19:40:05]

make port_ private and add:
  const std::string& port() const { return port_; }
for derived types to use

i see no reason not to do the same for the task runners above.

[juncai, 2015/11/14 01:51:24]

Done.

+
  private:
   friend class base::RefCounted<SerialIoHandler>;
 
   void MergeConnectionOptions(const serial::ConnectionOptions& options);
 
   // Continues an Open operation on the FILE thread.
   void StartOpen(const std::string& port,
                  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner);
 
   // Finalizes an Open operation (continued from StartOpen) on the IO thread.
@@ skipping 15 matching lines @@
   serial::ReceiveError read_cancel_reason_;
   bool read_canceled_;
 
   scoped_ptr<ReadOnlyBuffer> pending_write_buffer_;
   serial::SendError write_cancel_reason_;
   bool write_canceled_;
 
   // 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);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_SERIAL_SERIAL_IO_HANDLER_H_