[Cronet] Enforce implementation does not call through API classes

components/cronet/tools_unittest.py

Index: components/cronet/tools_unittest.py
diff --git a/components/cronet/tools_unittest.py b/components/cronet/tools_unittest.py
new file mode 100755
index 0000000000000000000000000000000000000000..1041406aaf278c2a39835464f0416dac06c4fa3c
--- /dev/null
+++ b/components/cronet/tools_unittest.py
@@ -0,0 +1,13 @@
+#!/usr/bin/python
+# 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.
+
+"""Run tools/ unittests."""
+
+import sys
+import unittest
+
+if __name__ == '__main__':
+  suite = unittest.TestLoader().discover('tools', pattern = "*_unittest.py")
+  sys.exit(0 if unittest.TextTestRunner().run(suite).wasSuccessful() else 1)