Only run recipe simulation tests if infra/ changes.

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 154 matching lines @@
                        'nanobench_flags.py' in x.LocalPath())
   for f in input_api.AffectedSourceFiles(sources):
     if 0 != subprocess.call(['python', f.LocalPath(), 'test']):
       results.append(output_api.PresubmitError('`python %s test` failed' % f))
   return results
 
 
 def _RecipeSimulationTest(input_api, output_api):
   """Run the recipe simulation test."""
   results = []
+  if not any(f.LocalPath().startswith('infra')
+             for f in input_api.AffectedFiles()):
+    return results
+
   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
 
 
@@ skipping 347 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