Require gn format in presubmit

PRESUBMIT.py

 # Copyright (c) 2013 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 Skia.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
@@ skipping 167 matching lines @@
 
   recipes_py = os.path.join('infra', 'bots', 'recipes.py')
   cmd = ['python', recipes_py, 'simulation_test']
   try:
     subprocess.check_output(cmd)
   except subprocess.CalledProcessError as e:
     results.append(output_api.PresubmitError(
         '`%s` failed:\n%s' % (' '.join(cmd), e.output)))
   return results
 
+def _CheckGNFormatted(input_api, output_api):
+  """Make sure any .gn files we're changing have been formatted."""
+  results = []
+  for f in input_api.AffectedFiles():
+    if not f.LocalPath().endswith('.gn'):
+      continue
+
+    cmd = ['gn', 'format', '--dry-run', f.LocalPath()]
+    try:
+      subprocess.check_output(cmd)
+    except subprocess.CalledProcessError:
+      fix = cmd[:]
+      fix[2] = '--in-place'
+      results.append(output_api.PresubmitError(
+          '`%s` failed, try\n\t%s' % (' '.join(cmd), ' '.join(fix))))
+  return results
+
 
 def _CommonChecks(input_api, output_api):
   """Presubmit checks common to upload and commit."""
   results = []
   sources = lambda x: (x.LocalPath().endswith('.h') or
                        x.LocalPath().endswith('.gypi') or
                        x.LocalPath().endswith('.gyp') or
                        x.LocalPath().endswith('.py') or
                        x.LocalPath().endswith('.sh') or
                        x.LocalPath().endswith('.m') or
@@ skipping 17 matching lines @@
   """Presubmit checks for the change on upload.
 
   The following are the presubmit checks:
   * Check change has one and only one EOL.
   """
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   # Run on upload, not commit, since the presubmit bot apparently doesn't have
   # coverage installed.
   results.extend(_RecipeSimulationTest(input_api, output_api))
+  results.extend(_CheckGNFormatted(input_api, output_api))
   return results
 
 
 def _CheckTreeStatus(input_api, output_api, json_url):
   """Check whether to allow commit.
 
   Args:
     input_api: input related apis.
     output_api: output related apis.
     json_url: url to download json style status.
@@ skipping 301 matching lines @@
     state and an error if it is in 'Closed' state.
   """
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(
       _CheckTreeStatus(input_api, output_api, json_url=(
           SKIA_TREE_STATUS_URL + '/banner-status?format=json')))
   results.extend(_CheckLGTMsForPublicAPI(input_api, output_api))
   results.extend(_CheckOwnerIsInAuthorsFile(input_api, output_api))
   return results