Add *_test_util.* to whitelist for test-only presubmit check.

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 46 matching lines @@
   that ignores header files and may have some false positives. A
   better implementation would probably need a proper C++ parser.
   """
   # We only scan .cc files and the like, as the declaration of
   # for-testing functions in header files are hard to distinguish from
   # calls to such functions without a proper C++ parser.
   source_extensions = r'\.(cc|cpp|cxx|mm)$'
   file_inclusion_pattern = r'.+%s' % source_extensions
   file_exclusion_patterns = (
       r'.*[/\\](test_|mock_).+%s' % source_extensions,
-      r'.+_test_(support|base)%s' % source_extensions,
+      r'.+_test_(base|support|util)%s' % source_extensions,
       r'.+_(api|browser|perf|unit|ui)?test%s' % source_extensions,
       r'.+profile_sync_service_harness%s' % source_extensions,
       )
   path_exclusion_patterns = (
       r'.*[/\\](test|tool(s)?)[/\\].*',
       # At request of folks maintaining this folder.
       r'chrome[/\\]browser[/\\]automation[/\\].*',
       )
 
   base_function_pattern = r'ForTest(ing)?|for_test(ing)?'
@@ skipping 243 matching lines @@
   # 2 trybots (compared against ~45 for Mac and Linux).
   # If any file matches something compiled on the main waterfall
   # android builder, use the android try server.
   android_re_list = ('^base/', '^ipc/', '^net/', '^sql/', '^jingle/',
                      '^build/common.gypi$')
   for f in affected_files:
     if any(re.search(r, f) for r in android_re_list):
       preferred.append('android')
       break
   return preferred