Add a presubmit check that catches |const NSString*| and friends.

PRESUBMIT.py

 # Copyright (c) 2010 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 12 matching lines @@
 _LICENSE_HEADER = (
      r".*? Copyright \(c\) 20[0-9\-]{2,7} The Chromium Authors\. All rights "
        r"reserved\." "\n"
      r".*? Use of this source code is governed by a BSD-style license that can "
        "be\n"
      r".*? found in the LICENSE file\."
        "\n"
 )
 
 
+def _CheckConstNSObject(input_api, output_api, source_file_filter):
+  """Checks to make sure no objective-c files have |const NSSomeClass*|."""
+  pattern = input_api.re.compile(r'const\s+NS\w*\s*\*')
+  files = []
+  for f in input_api.AffectedSourceFiles(source_file_filter):
+    if f.LocalPath().endswith('.h') or f.LocalPath().endswith('.mm'):
+      contents = input_api.ReadFile(f)
+      if pattern.search(contents):
+        files.append(f)
+
+  if len(files):
+    if input_api.is_committing:
+      res_type = output_api.PresubmitPromptWarning
+    else:
+      res_type = output_api.PresubmitNotifyResult
+    return [ res_type('|const NSClass*| is wrong, see ' +
+                      'http://dev.chromium.org/developers/clang-mac',
+                      files) ]
+  return []
+
+
 def _CommonChecks(input_api, output_api):
   results = []
   # What does this code do?
   # It loads the default black list (e.g. third_party, experimental, etc) and
   # add our black list (breakpad, skia and v8 are still not following
   # google style and are not really living this repository).
   # See presubmit_support.py InputApi.FilterSourceFile for the (simple) usage.
   black_list = input_api.DEFAULT_BLACK_LIST + _EXCLUDED_PATHS
   white_list = input_api.DEFAULT_WHITE_LIST + _TEXT_FILES
   sources = lambda x: input_api.FilterSourceFile(x, black_list=black_list)
   text_files = lambda x: input_api.FilterSourceFile(x, black_list=black_list,
                                                     white_list=white_list)
   results.extend(input_api.canned_checks.CheckLongLines(
       input_api, output_api, source_file_filter=sources))
   results.extend(input_api.canned_checks.CheckChangeHasNoTabs(
       input_api, output_api, source_file_filter=sources))
   results.extend(input_api.canned_checks.CheckChangeHasNoStrayWhitespace(
       input_api, output_api, source_file_filter=sources))
   results.extend(input_api.canned_checks.CheckChangeHasBugField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasTestField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeSvnEolStyle(
       input_api, output_api, source_file_filter=text_files))
   results.extend(input_api.canned_checks.CheckSvnForCommonMimeTypes(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckLicense(
       input_api, output_api, _LICENSE_HEADER, source_file_filter=sources))
+  results.extend(_CheckConstNSObject(
+      input_api, output_api, source_file_filter=sources))
   return results
 
 
 def CheckChangeOnUpload(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   return results
 
 
 def CheckChangeOnCommit(input_api, output_api):
@@ skipping 35 matching lines @@
       input_api,
       output_api,
       'http://build.chromium.org/buildbot/waterfall/json/builders?filter=1',
       6,
       IGNORED_BUILDERS))
   return results
 
 
 def GetPreferredTrySlaves():
   return ['win', 'linux', 'mac']