Rewrite presubmit scripts to use new EnsureCQIncludeTrybotsAreAdded.

ui/file_manager/PRESUBMIT.py

 # 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.
 
-import re
-
-
 def PostUploadHook(cl, change, output_api):
-  rietveld_obj = cl.RpcServer()
-  description = rietveld_obj.get_description(cl.issue)
-
-  existing_bots = (change.CQ_INCLUDE_TRYBOTS or '').split(';')
-  clean_bots = set(filter(None, map(lambda s: s.strip(), existing_bots)))
-  new_bots = clean_bots | set(
-      ['master.tryserver.chromium.linux:closure_compilation'])
-  new_tag = 'CQ_INCLUDE_TRYBOTS=%s' % ';'.join(new_bots)
-
-  if clean_bots:
-    tag_reg = '^CQ_INCLUDE_TRYBOTS=.*$'
-    new_description = re.sub(tag_reg, new_tag, description, flags=re.M | re.I)
-  else:
-    new_description = description + '\n' + new_tag
-
-  if new_description == description:
-    return []
-
-  rietveld_obj.update_description(cl.issue, new_description)
-  return [output_api.PresubmitNotifyResult(
-      'Automatically added optional Closure bots to run on CQ.')]
+  return output_api.EnsureCQIncludeTrybotsAreAdded(
+    cl,
+    [
+      'master.tryserver.chromium.linux:closure_compilation',
+    ],
+    'Automatically added optional Closure bots to run on CQ.')