Add support for file locking

runtime/bin/io_service.h

 // Copyright (c) 2013, 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_IO_SERVICE_H_
 #define BIN_IO_SERVICE_H_
 
 #include "bin/builtin.h"
 #include "bin/utils.h"
 
@@ skipping 23 matching lines @@
   V(File, Read, 17)                                                            \
   V(File, ReadInto, 18)                                                        \
   V(File, WriteFrom, 19)                                                       \
   V(File, CreateLink, 20)                                                      \
   V(File, DeleteLink, 21)                                                      \
   V(File, RenameLink, 22)                                                      \
   V(File, LinkTarget, 23)                                                      \
   V(File, Type, 24)                                                            \
   V(File, Identical, 25)                                                       \
   V(File, Stat, 26)                                                            \
-  V(Socket, Lookup, 27)                                                        \
-  V(Socket, ListInterfaces, 28)                                                \
-  V(Socket, ReverseLookup, 29)                                                 \
-  V(Directory, Create, 30)                                                     \
-  V(Directory, Delete, 31)                                                     \
-  V(Directory, Exists, 32)                                                     \
-  V(Directory, CreateTemp, 33)                                                 \
-  V(Directory, ListStart, 34)                                                  \
-  V(Directory, ListNext, 35)                                                   \
-  V(Directory, ListStop, 36)                                                   \
-  V(Directory, Rename, 37)                                                     \
-  V(SSLFilter, ProcessFilter, 38)
+  V(File, Lock, 27)                                                            \
+  V(Socket, Lookup, 28)                                                        \
+  V(Socket, ListInterfaces, 29)                                                \
+  V(Socket, ReverseLookup, 30)                                                 \
+  V(Directory, Create, 31)                                                     \
+  V(Directory, Delete, 32)                                                     \
+  V(Directory, Exists, 33)                                                     \
+  V(Directory, CreateTemp, 34)                                                 \
+  V(Directory, ListStart, 35)                                                  \
+  V(Directory, ListNext, 36)                                                   \
+  V(Directory, ListStop, 37)                                                   \
+  V(Directory, Rename, 38)                                                     \
+  V(SSLFilter, ProcessFilter, 39)
 
 #define DECLARE_REQUEST(type, method, id)                                      \
   k##type##method##Request = id,
 
 class IOService {
  public:
   enum {
 IO_SERVICE_REQUEST_LIST(DECLARE_REQUEST)
   };
 
   static Dart_Port GetServicePort();
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_IO_SERVICE_H_