Add gate keeper logic to presubmit commit check.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/21338002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15978 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

PRESUBMIT.py

@@ -69,4 +69,7 @@ def CheckChangeOnCommit(input_api, output_api):
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
+  results.extend(input_api.canned_checks.CheckTreeIsOpen(
+      input_api, output_api,
+      json_url='http://v8-status.appspot.com/current?format=json'))
   return results