Rewrite presubmit scripts to use new EnsureCQIncludeTrybotsAreAdded.

cc/PRESUBMIT.py

Index: cc/PRESUBMIT.py
diff --git a/cc/PRESUBMIT.py b/cc/PRESUBMIT.py
index 6fc669b93f3d44f44ec36b7630322c1ea55a6e8b..c89768a81b6ce74f8bdb921f934d5b819d27c167 100644
--- a/cc/PRESUBMIT.py
+++ b/cc/PRESUBMIT.py
@@ -328,26 +328,10 @@ def CheckChangeOnUpload(input_api, output_api):
 def PostUploadHook(cl, change, output_api):
   """git cl upload will call this hook after the issue is created/modified.
 
-  This hook adds extra try bots list to the CL description in order to run
-  Blink tests in addition to CQ try bots.
+  This hook adds an extra try bot list to the CL description in order to run
+  Blink tests in addition to the CQ try bots.
   """
-  rietveld_obj = cl.RpcServer()
-  issue = cl.issue
-  description = rietveld_obj.get_description(issue)
-  if re.search(r'^CQ_INCLUDE_TRYBOTS=.*', description, re.M | re.I):
-    return []
-
-  bots = [
-    'master.tryserver.blink:linux_trusty_blink_rel',
-  ]
-
-  results = []
-  new_description = description
-  new_description += '\nCQ_INCLUDE_TRYBOTS=%s' % ';'.join(bots)
-  results.append(output_api.PresubmitNotifyResult(
-      'Automatically added Blink trybots to run Blink tests on CQ.'))
-
-  if new_description != description:
-    rietveld_obj.update_description(issue, new_description)
-
-  return results
+  return output_api.EnsureCQIncludeTrybotsAreAdded(
+    cl,
+    ['master.tryserver.blink:linux_trusty_blink_rel'],
+    'Automatically added Blink trybots to run Blink tests on CQ.')