Update LTO flags for Mac.

chrome/chrome_dll.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.
 {
   'conditions': [
     ['OS=="mac" or OS=="win"', {
       'targets': [
         {
           'target_name': 'chrome_dll',
           'type': 'none',
@@ skipping 277 matching lines @@
                 'app/chrome_crash_reporter_client_mac.mm',
               ],
               'xcode_settings': {
                 # Define the order of symbols within the framework.  This
                 # sets -order_file.
                 'ORDER_FILE': 'app/framework.order',
               },
               'include_dirs': [
                 '<(grit_out_dir)',
               ],
+            }],
+            # This step currently fails when using LTO. TODO(pcc): Re-enable.
+            ['OS=="mac" and use_lto==0', {
               'postbuilds': [
                 {
                   # This step causes an error to be raised if the .order file
                   # does not account for all global text symbols.  It
                   # validates the completeness of the .order file.
                   'postbuild_name': 'Verify global text symbol order',
                   'variables': {
                     'verify_order_path': 'tools/build/mac/verify_order',
                   },
                   'action': [
@@ skipping 60 matching lines @@
               'dependencies': [
                 '../pdf/pdf.gyp:pdf',
               ],
             }],
           ],
         },  # target chrome_child_dll
       ],
     }],
   ],
 }