Implement break signal for serial api.

extensions/browser/api/serial/serial_connection.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 EXTENSIONS_BROWSER_API_SERIAL_SERIAL_CONNECTION_H_
 #define EXTENSIONS_BROWSER_API_SERIAL_SERIAL_CONNECTION_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 94 matching lines @@
   // successfully read.
   bool GetControlSignals(
       core_api::serial::DeviceControlSignals* control_signals) const;
 
   // Sets one or more control signals (DTR and/or RTS). Returns |true| iff
   // the signals were successfully set. Unininitialized flags in the
   // HostControlSignals structure are left unchanged.
   bool SetControlSignals(
       const core_api::serial::HostControlSignals& control_signals);
 
+  // Suspend character transmission. Known as setting/sending 'Break' signal.
+  bool SetBreak();
+
+  // Restore character transmission. Known as clear/stop sending 'Break' signal.
+  bool ClearBreak();
+
   // Overrides |io_handler_| for testing.
   void SetIoHandlerForTest(scoped_refptr<device::SerialIoHandler> handler);
 
   static const BrowserThread::ID kThreadId = BrowserThread::IO;
 
  private:
   friend class ApiResourceManager<SerialConnection>;
   static const char* service_name() { return "SerialConnectionManager"; }
 
   // Encapsulates a cancelable, delayed timeout task. Posts a delayed
@@ skipping 83 matching lines @@
 template <>
 struct TypeConverter<device::serial::ConnectionOptionsPtr,
                      extensions::core_api::serial::ConnectionOptions> {
   static device::serial::ConnectionOptionsPtr Convert(
       const extensions::core_api::serial::ConnectionOptions& input);
 };
 
 }  // namespace mojo
 
 #endif  // EXTENSIONS_BROWSER_API_SERIAL_SERIAL_CONNECTION_H_