Implement break signal for serial api.

device/serial/serial_io_handler_posix.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_POSIX_H_
 #define DEVICE_SERIAL_SERIAL_IO_HANDLER_POSIX_H_
 
 #include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/thread_task_runner_handle.h"
 #include "device/serial/serial_io_handler.h"
 
 namespace device {
 
 class SerialIoHandlerPosix : public SerialIoHandler,
                              public base::MessageLoopForIO::Watcher {
  protected:
   // SerialIoHandler impl.
   void ReadImpl() override;
   void WriteImpl() override;
   void CancelReadImpl() override;
   void CancelWriteImpl() override;
   bool ConfigurePortImpl() override;
   bool Flush() const override;
   serial::DeviceControlSignalsPtr GetControlSignals() const override;
   bool SetControlSignals(
       const serial::HostControlSignals& control_signals) override;
   serial::ConnectionInfoPtr GetPortInfo() const override;
+  bool SetBreak() override;
+  bool ClearBreak() override;
   void RequestAccess(
       const std::string& port,
       scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner) override;
 
  private:
   friend class SerialIoHandler;
 
   SerialIoHandlerPosix(
       scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner,
@@ skipping 13 matching lines @@
   // Flags indicating if the message loop is watching the device for IO events.
   bool is_watching_reads_;
   bool is_watching_writes_;
 
   DISALLOW_COPY_AND_ASSIGN(SerialIoHandlerPosix);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_SERIAL_SERIAL_IO_HANDLER_POSIX_H_