Removing file_thread_task_runner parameter from SerialIoHandler

extensions/browser/api/serial/serial_connection.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 "extensions/browser/api/serial/serial_connection.h"
 
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
@@ skipping 150 matching lines @@
                                    const std::string& owner_extension_id)
     : ApiResource(owner_extension_id),
       port_(port),
       persistent_(false),
       buffer_size_(kDefaultBufferSize),
       receive_timeout_(0),
       send_timeout_(0),
       paused_(false),
       io_handler_(device::SerialIoHandler::Create(
           content::BrowserThread::GetTaskRunnerForThread(
-              content::BrowserThread::FILE),
-          content::BrowserThread::GetTaskRunnerForThread(
               content::BrowserThread::UI))) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 }
 
 SerialConnection::~SerialConnection() {
   io_handler_->CancelRead(device::serial::ReceiveError::DISCONNECTED);
   io_handler_->CancelWrite(device::serial::SendError::DISCONNECTED);
 }
 
 bool SerialConnection::IsPersistent() const {
@@ skipping 230 matching lines @@
   output->parity_bit = extensions::ConvertParityBitToMojo(input.parity_bit);
   output->stop_bits = extensions::ConvertStopBitsToMojo(input.stop_bits);
   if (input.cts_flow_control.get()) {
     output->has_cts_flow_control = true;
     output->cts_flow_control = *input.cts_flow_control;
   }
   return output;
 }
 
 }  // namespace mojo