Fix DevFS on Android devices

runtime/bin/embedded_dart_io.h

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef BIN_EMBEDDED_DART_IO_H_
 #define BIN_EMBEDDED_DART_IO_H_
 
 namespace dart {
 namespace bin {
 
 // Bootstraps 'dart:io'.
 void BootstrapDartIo();
 
+// Lets dart:io know where the system temporary directory is located.
+// Currently only wired up on Android.
+void SetSystemTempDirectory(const char* system_temp);
+
 // Tells the system whether to capture Stdout events.
 void SetCaptureStdout(bool value);
 
 // Tells the system whether to capture Stderr events.
 void SetCaptureStderr(bool value);
 
 // Should Stdout events be captured?
 bool ShouldCaptureStdout();
 
 // Should Stderr events be captured?
 bool ShouldCaptureStderr();
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_EMBEDDED_DART_IO_H_