Add checks for 'DO NOT''SUBMIT' in description and file content

NoTry: true
Bug: skia:
Change-Id: I5ce8c40a7deae690b04e7fbe4ac22fa63888ffc7
Reviewed-on: https://skia-review.googlesource.com/45882
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index f1c80d3..3eb71a5 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -621,4 +621,8 @@
           SKIA_TREE_STATUS_URL + '/banner-status?format=json')))
   results.extend(_CheckLGTMsForPublicAPI(input_api, output_api))
   results.extend(_CheckOwnerIsInAuthorsFile(input_api, output_api))
+  # Checks for the presence of 'DO NOT''SUBMIT' in CL description and in
+  # content of files.
+  results.extend(
+      input_api.canned_checks.CheckDoNotSubmit(input_api, output_api))
   return results