Force sync integration try jobs on patches that touch sync dependencies

base/PRESUBMIT.py

Index: base/PRESUBMIT.py
diff --git a/base/PRESUBMIT.py b/base/PRESUBMIT.py
new file mode 100644
index 0000000000000000000000000000000000000000..128465919facc2bfe13db6b3324d5990e7d7165f
--- /dev/null
+++ b/base/PRESUBMIT.py
@@ -0,0 +1,13 @@
+#!/usr/bin/python
+# Copyright (c) 2011 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.
+
+"""Chromium presubmit script for src/base.
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details on the presubmit API built into gcl.
+"""
+
+def GetPreferredTrySlaves():
+  return ['win', 'linux', 'mac', 'win_sync', 'linux_sync', 'mac_sync']