Add Cronet trybots to all net changes.

Bug: 712733
Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I98565609711612b21d5381c0f60bdcbedc9da33b
Reviewed-on: https://chromium-review.googlesource.com/741886Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Paul Jensen <pauljensen@chromium.org>
Commit-Queue: Misha Efimov <mef@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512331}

net/PRESUBMIT.py

+# Copyright 2017 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.
+
+"""Presubmit script for net/.
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into depot_tools.
+"""
+
+def PostUploadHook(cl, change, output_api):
+  """git cl upload will call this hook after the issue is created/modified.
+
+  This hook adds an extra line to the CL description in order to run Cronet
+  tests in addition to CQ bots.
+  """
+
+  # TODO(crbug.com/712733): Remove this once Cronet bots are deployed on CQ.
+  try_bots = ['master.tryserver.chromium.android:android_cronet_tester',
+              'master.tryserver.chromium.mac:ios-simulator-cronet']
+
+  return output_api.EnsureCQIncludeTrybotsAreAdded(
+    cl, try_bots, 'Automatically added Cronet trybots to run tests on CQ.')