Implement break signal for serial api.

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 65 matching lines @@
 
   // Performs platform-specific port configuration. Returns |true| iff
   // configuration was successful.
   bool ConfigurePort(const serial::ConnectionOptions& options);
 
   // Performs a platform-specific port configuration query. Fills values in an
   // existing ConnectionInfo. Returns |true| iff port configuration was
   // successfully retrieved.
   virtual serial::ConnectionInfoPtr GetPortInfo() const = 0;
 
+  // Initiates a BREAK signal. Places the transmission line in a break state
+  // until the |ClearBreak| is called.
+  virtual bool SetBreak() = 0;
+
+  // Terminates the BREAK signal. Places the transmission line in a nonbreak
+  // state.
+  virtual bool ClearBreak() = 0;
+
  protected:
   explicit SerialIoHandler(
       scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> ui_thread_task_runner);
   virtual ~SerialIoHandler();
 
   // Performs a platform-specific read operation. This must guarantee that
   // ReadCompleted is called when the underlying async operation is completed
   // or the SerialIoHandler instance will leak.
   // NOTE: Implementations of ReadImpl should never call ReadCompleted directly.
@@ skipping 116 matching lines @@
   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_