Add a presubmit check for "? true : false".

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 gcl.
 """
 
@@ skipping 359 matching lines @@
       files.append(f)
 
   if files:
     return [output_api.PresubmitError(
         'Do not use #pragma once in header files.\n'
         'See http://www.chromium.org/developers/coding-style#TOC-File-headers',
         files)]
   return []
 
 
+def _CheckNoTrinaryTrueFalse(input_api, output_api):
+  """Checks to make sure we don't introduce use of foo ? true : false."""
+  problems = []
+  pattern = input_api.re.compile(r'\?\s*(true|false)\s*:\s*(true|false)')
+  for f in input_api.AffectedFiles():
+    if not f.LocalPath().endswith(('.cc', '.h', '.inl', '.m', '.mm')):
+      continue
+
+    for line_num, line in f.ChangedContents():
+      if pattern.match(line):
+        problems.append('    %s:%d' % (f.LocalPath(), line_num))
+
+  if not problems:
+    return []
+  return [output_api.PresubmitPromptWarning(
+      'Please consider avoiding the "? true : false" pattern if possible.\n' +
+      '\n'.join(problems))]
+
+
 def _CheckUnwantedDependencies(input_api, output_api):
   """Runs checkdeps on #include statements added in this
   change. Breaking - rules is an error, breaking ! rules is a
   warning.
   """
   # We need to wait until we have an input_api object and use this
   # roundabout construct to import checkdeps because this file is
   # eval-ed and thus doesn't have __file__.
   original_sys_path = sys.path
   try:
@@ skipping 69 matching lines @@
       input_api, output_api, excluded_paths=_EXCLUDED_PATHS))
   results.extend(_CheckAuthorizedAuthor(input_api, output_api))
   results.extend(
     _CheckNoProductionCodeUsingTestOnlyFunctions(input_api, output_api))
   results.extend(_CheckNoIOStreamInHeaders(input_api, output_api))
   results.extend(_CheckNoUNIT_TESTInSourceFiles(input_api, output_api))
   results.extend(_CheckNoNewWStrings(input_api, output_api))
   results.extend(_CheckNoDEPSGIT(input_api, output_api))
   results.extend(_CheckNoBannedFunctions(input_api, output_api))
   results.extend(_CheckNoPragmaOnce(input_api, output_api))
+  results.extend(_CheckNoTrinaryTrueFalse(input_api, output_api))
   results.extend(_CheckUnwantedDependencies(input_api, output_api))
   results.extend(_CheckFilePermissions(input_api, output_api))
   return results
 
 
 def _CheckSubversionConfig(input_api, output_api):
   """Verifies the subversion config file is correctly setup.
 
   Checks that autoprops are enabled, returns an error otherwise.
   """
@@ skipping 116 matching lines @@
   # Same for ash and chromeos.
   if any(re.search('[/_](ash|aura)', f) for f in files):
     trybots += ['linux_chromeos', 'linux_chromeos_clang:compile', 'win_aura',
                 'linux_chromeos_asan']
   else:
     if any(re.search('[/_]chromeos', f) for f in files):
       trybots += ['linux_chromeos', 'linux_chromeos_clang:compile',
                   'linux_chromeos_asan']
 
   return trybots