Fix define typo in Mac OS X build

build/common.gypi

 # 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 4575 matching lines @@
         ],  # target_conditions
       },  # target_defaults
     }],  # OS=="mac" or OS=="ios"
     ['OS=="mac"', {
       'target_defaults': {
         'defines': [
           # Prevent Mac OS X AssertMacros.h from defining macros that collide
           # with common names, like 'check', 'require', and 'verify'.
           # (Included by system header. Also exists on iOS but not included.)
           # http://opensource.apple.com/source/CarbonHeaders/CarbonHeaders-18.1/AssertMacros.h
-          '__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORE=0',
+          '__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES=0',
         ],
         'variables': {
           # These should end with %, but there seems to be a bug with % in
           # variables that are intended to be set to different values in
           # different targets, like these.
           'mac_pie': 1,        # Most executables can be position-independent.
           # Strip debugging symbols from the target.
           'mac_strip': '<(mac_strip_release)',
           'conditions': [
             ['asan==1', {
@@ skipping 758 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }