Add PRESUBMIT check for #ifdefs on values that are always defined.

PRESUBMIT_test.py

 #!/usr/bin/env python
 # 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.
 
 import glob
 import json
 import os
 import re
 import subprocess
@@ skipping 395 matching lines @@
     self.assertTrue(':1 OS_WINDOWS' in errors[0])
     self.assertTrue('(did you mean OS_WIN?)' in errors[0])
 
   def testValidOSMacroNames(self):
     lines = ['#if defined(%s)' % m for m in PRESUBMIT._VALID_OS_MACROS]
     errors = PRESUBMIT._CheckForInvalidOSMacrosInFile(
         MockInputApi(), MockFile('some/path/foo_platform.cc', lines))
     self.assertEqual(0, len(errors))
 
 
+class InvalidIfDefinedMacroNamesTest(unittest.TestCase):
+  def testInvalidIfDefinedMacroNames(self):
+    lines = ['#if defined(TARGET_IPHONE_SIMULATOR)',
+             '#if !defined(TARGET_IPHONE_SIMULATOR)',
+             '#elif defined(TARGET_IPHONE_SIMULATOR)',
+             '#ifdef TARGET_IPHONE_SIMULATOR',
+             ' # ifdef TARGET_IPHONE_SIMULATOR',
+             '# if defined(VALID) || defined(TARGET_IPHONE_SIMULATOR)',
+             '# else  // defined(TARGET_IPHONE_SIMULATOR)',
+             '#endif  // defined(TARGET_IPHONE_SIMULATOR)',]
+    errors = PRESUBMIT._CheckForInvalidIfDefinedMacrosInFile(
+        MockInputApi(), MockFile('some/path/source.mm', lines))
+    self.assertEqual(len(lines), len(errors))
+
+  def testValidIfDefinedMacroNames(self):
+    lines = ['#if defined(FOO)',
+             '#ifdef BAR',]
+    errors = PRESUBMIT._CheckForInvalidIfDefinedMacrosInFile(
+        MockInputApi(), MockFile('some/path/source.cc', lines))
+    self.assertEqual(0, len(errors))
+
+
 class CheckAddedDepsHaveTetsApprovalsTest(unittest.TestCase):
   def testFilesToCheckForIncomingDeps(self):
     changed_lines = [
       '"+breakpad",',
       '"+chrome/installer",',
       '"+chrome/plugin/chrome_content_plugin_client.h",',
       '"+chrome/utility/chrome_content_utility_client.h",',
       '"+chromeos/chromeos_paths.h",',
       '"+components/crash",',
       '"+components/nacl/common",',
@@ skipping 330 matching lines @@
     }
     for master, bots in bots.iteritems():
       for bot in bots:
         self.assertEqual(master, PRESUBMIT.GetTryServerMasterForBot(bot),
                          'bot=%s: expected %s, computed %s' % (
             bot, master, PRESUBMIT.GetTryServerMasterForBot(bot)))
 
 
 if __name__ == '__main__':
   unittest.main()