Turn on clang format as an upload step for all the repo.

PRESUBMIT.py

 # Copyright (c) 2012 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
@@ skipping 2297 matching lines @@
         'Please make sure there are no privacy sensitive bits of data in SYSLOG'
         ' calls.\nFiles to check:\n', items=syslog_files)]
   return []
 
 
 def CheckChangeOnUpload(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(_CheckValidHostsInDEPS(input_api, output_api))
   results.extend(
+      input_api.canned_checks.CheckPatchFormatted(input_api, output_api))
+  results.extend(
       input_api.canned_checks.CheckGNFormatted(input_api, output_api))
   results.extend(_CheckUmaHistogramChanges(input_api, output_api))
   results.extend(_AndroidSpecificOnUploadChecks(input_api, output_api))
   results.extend(_CheckSyslogUseWarning(input_api, output_api))
   results.extend(_CheckGoogleSupportAnswerUrl(input_api, output_api))
   return results
 
 
 def GetTryServerMasterForBot(bot):
   """Returns the Try Server master for the given bot.
@@ skipping 34 matching lines @@
 
 def CheckChangeOnCommit(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   # Make sure the tree is 'open'.
   results.extend(input_api.canned_checks.CheckTreeIsOpen(
       input_api,
       output_api,
       json_url='http://chromium-status.appspot.com/current?format=json'))
 
+  results.extend(
+      input_api.canned_checks.CheckPatchFormatted(input_api, output_api))

[Dan Beam, 2017/02/10 19:10:06]

fyi: this certainly appears to be running formatting checks on commit as well

[Dan Beam, 2017/02/10 20:11:39]

follow up: as dcheng@ mentioned on chromium-dev@: because this check returns
PresubmitPromptWarnings (rather than PresubmitErrors), this will not block a CQ

   results.extend(input_api.canned_checks.CheckChangeHasBugField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
   return results