Implement break signal for serial api.

extensions/common/api/serial.idl

 // 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.
 
 // Use the <code>chrome.serial</code> API to read from and write to a device
 // connected to a serial port.
 namespace serial {
 
   dictionary DeviceInfo {
     // The device's system path. This should be passed as the <code>path</code>
@@ skipping 153 matching lines @@
     long bytesSent;
 
     // An error code if an error occurred.
     SendError? error;
   };
 
   callback SendCallback = void (SendInfo sendInfo);
 
   callback FlushCallback = void (boolean result);
 
+  callback SetBreakCallback = void (boolean result);
+
+  callback ClearBreakCallback = void (boolean result);
+
   // The set of control signals which may be sent to a connected serial device
   // using <code>setControlSignals</code>. Note that support for these signals
   // is device-dependent.
   dictionary HostControlSignals {
     // DTR (Data Terminal Ready).
     boolean? dtr;
 
     // RTS (Request To Send).
     boolean? rts;
   };
@@ skipping 116 matching lines @@
     static void getControlSignals(long connectionId,
                                   GetControlSignalsCallback callback);
 
     // Sets the state of control signals on a given connection.
     // |connectionId| : The id of the connection.
     // |signals| : The set of signal changes to send to the device.
     // |callback| : Called once the control signals have been set.
     static void setControlSignals(long connectionId,
                                   HostControlSignals signals,
                                   SetControlSignalsCallback callback);
+
+    // Suspends character transmission on a given connection and places the
+    // transmission line in a break state until the clearBreak is called.
+    // |connectionId| : The id of the connection.
+    static void setBreak(long connectionId, SetBreakCallback callback);
+
+    // Restore character transmission on a given connection and place the
+    // transmission line in a nonbreak state.
+    // |connectionId| : The id of the connection.
+    static void clearBreak(long connectionId, ClearBreakCallback callback);
   };
 
   interface Events {
     // Event raised when data has been read from the connection.
     // |info| : Event data.
     static void onReceive(ReceiveInfo info);
 
     // Event raised when an error occurred while the runtime was waiting for
     // data on the serial port. Once this event is raised, the connection may be
     // set to <code>paused</code>. A <code>"timeout"</code> error does not pause
     // the connection.
     static void onReceiveError(ReceiveErrorInfo info);
   };
 };