infra: add presubmit check for recipes

infra/PRESUBMIT.py

Index: infra/PRESUBMIT.py
diff --git a/infra/PRESUBMIT.py b/infra/PRESUBMIT.py
new file mode 100644
index 0000000000000000000000000000000000000000..c50be9bbf7589e9e0402775485b2369d2e3f6107
--- /dev/null
+++ b/infra/PRESUBMIT.py
@@ -0,0 +1,19 @@
+# Copyright 2016 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.
+
+def CommonChecks(input_api, output_api):
+  results = []
+
+  results.extend(input_api.RunTests(
+      input_api.canned_checks.GetUnitTestsInDirectory(
+          input_api,
+          output_api,
+          input_api.os_path.join('unittests'),
+          whitelist=[r'.+_test\.py'])))
+
+  return results
+
+
+CheckChangeOnUpload = CommonChecks
+CheckChangeOnCommit = CommonChecks