Add an XPC implementation of sandbox::MessageServer.

sandbox/mac/xpc.cc

Index: sandbox/mac/xpc.cc
diff --git a/sandbox/mac/xpc.cc b/sandbox/mac/xpc.cc
new file mode 100644
index 0000000000000000000000000000000000000000..670d8ad9e564169eb5e2b2d1c9bbfae770cdc583
--- /dev/null
+++ b/sandbox/mac/xpc.cc
@@ -0,0 +1,20 @@
+// 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.
+
+#include "sandbox/mac/xpc.h"
+
+namespace sandbox {
+
+bool InitializeXPC() {
+  std::vector<std::string> path_list;
+  path_list.push_back("/usr/lib/system/libxpc.dylib");
+
+  sandbox_mac::StubPathMap path_map;
+  path_map[sandbox_mac::kModuleXpc_stubs] = path_list;
+  path_map[sandbox_mac::kModuleXpc_private_stubs] = path_list;
+
+  return sandbox_mac::InitializeStubs(path_map);
+}
+
+}  // namespace sandbox