Send try jobs that touch policy code to the linux_chromeos bot too.

chrome/browser/policy/PRESUBMIT.py

Index: chrome/browser/policy/PRESUBMIT.py
diff --git a/chrome/browser/policy/PRESUBMIT.py b/chrome/browser/policy/PRESUBMIT.py
new file mode 100644
index 0000000000000000000000000000000000000000..da65b741c2a58647e831e6a37ac7a0f314a1baf3
--- /dev/null
+++ b/chrome/browser/policy/PRESUBMIT.py
@@ -0,0 +1,15 @@
+# Copyright (c) 2012 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 chrome/browser/policy.
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details on the presubmit API built into gcl.
+"""
+
+def GetPreferredTrySlaves():
+  return [
+    'linux_chromeos',
+    'linux_chromeos_clang:compile',
+  ]