Explicitly put serial port fd in non-blocking mode on Chrome OS.

device/serial/serial_io_handler.cc

 // 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.
 
 #include "device/serial/serial_io_handler.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 156 matching lines @@
   if (!file.IsValid()) {
     LOG(ERROR) << "Failed to open serial port: "
                << base::File::ErrorToString(file.error_details());
     callback.Run(false);
     return;
   }
 
   file_ = std::move(file);
 
   bool success = PostOpen() && ConfigurePortImpl();
-  if (!success) {
+  if (!success)
     Close();
-  }
 
   callback.Run(success);
 }
 
 bool SerialIoHandler::PostOpen() {
   return true;
 }
 
 void SerialIoHandler::Close() {
   if (file_.IsValid()) {
@@ skipping 97 matching lines @@
 }
 
 void SerialIoHandler::QueueWriteCompleted(int bytes_written,
                                           serial::SendError error) {
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
       base::Bind(&SerialIoHandler::WriteCompleted, this, bytes_written, error));
 }
 
 }  // namespace device