Add PRESUBMIT to make sure that perf JSON configs are always up-to-date

tools/perf/PRESUBMIT.py

 # Copyright 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.
 
 """Presubmit script for changes affecting tools/perf/.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
 import os
 import sys
 
 
 def _CommonChecks(input_api, output_api):
   """Performs common checks, which includes running pylint."""
   results = []
 
   results.extend(_CheckWprShaFiles(input_api, output_api))
   results.extend(_CheckJson(input_api, output_api))
+  results.extend(_CheckPerfJsonUpToDate(input_api, output_api))
   results.extend(input_api.RunTests(input_api.canned_checks.GetPylint(
       input_api, output_api, extra_paths_list=_GetPathsToPrepend(input_api),
       pylintrc='pylintrc')))
   return results
 
 
 def _GetPathsToPrepend(input_api):
   perf_dir = input_api.PresubmitLocalPath()
   chromium_src_dir = input_api.os_path.join(perf_dir, '..', '..')
   telemetry_dir = input_api.os_path.join(
       chromium_src_dir, 'third_party', 'catapult', 'telemetry')
   experimental_dir = input_api.os_path.join(
       chromium_src_dir, 'third_party', 'catapult', 'experimental')
   return [
       telemetry_dir,
       input_api.os_path.join(telemetry_dir, 'third_party', 'mock'),
       experimental_dir,
   ]
 
 
+def _RunArgs(args, input_api):
+  p = input_api.subprocess.Popen(args, stdout=input_api.subprocess.PIPE,
+                                 stderr=input_api.subprocess.STDOUT)
+  out, _ = p.communicate()
+  return (out, p.returncode)
+
+
+def _CheckPerfJsonUpToDate(input_api, output_api):
+  results = []
+  perf_dir = input_api.PresubmitLocalPath()
+  out, return_code = _RunArgs([
+      input_api.python_executable,
+      input_api.os_path.join(perf_dir, 'generate_perf_json.py'),
+      '--validate-only'], input_api)
+  if return_code:
+      results.append(output_api.PresubmitError(
+          'Validating Perf JSON configs failed.', long_text=out))
+  return results
+
+
 def _CheckWprShaFiles(input_api, output_api):
   """Check whether the wpr sha files have matching URLs."""
   old_sys_path = sys.path
   try:
     perf_dir = input_api.PresubmitLocalPath()
     py_utils_path = os.path.abspath(os.path.join(
         perf_dir, '..', '..', 'third_party', 'catapult', 'common', 'py_utils'))
     sys.path.insert(1, py_utils_path)
     from py_utils import cloud_storage  # pylint: disable=import-error
   finally:
@@ skipping 37 matching lines @@
 def CheckChangeOnUpload(input_api, output_api):
   report = []
   report.extend(_CommonChecks(input_api, output_api))
   return report
 
 
 def CheckChangeOnCommit(input_api, output_api):
   report = []
   report.extend(_CommonChecks(input_api, output_api))
   return report