win/clang: Suppress another -Wunused-private-field warning.

third_party/libphonenumber/libphonenumber.gyp

 # 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.
 
 {
   'target_defaults': {
     'include_dirs': [
       'src',
       'src/test',
       # The libphonenumber source (and test code) expects the
@@ skipping 120 matching lines @@
     ],
     'dependencies': [
       '../icu/icu.gyp:icui18n',
       '../icu/icu.gyp:icuuc',
       '../../base/base.gyp:run_all_unittests',
       '../../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
       '../../testing/gmock.gyp:gmock',
       '../../testing/gtest.gyp:gtest',
       'libphonenumber_without_metadata',
     ],
+    'variables': {
+      'clang_warning_flags': [
+        # https://github.com/googlei18n/libphonenumber/pull/741
+        '-Wno-unused-private-field',
+      ],
+    },
     'conditions': [
       ['OS=="win"', {
         'action': [
           '/wo4309',
         ],
       }],
       # libphonenumber needs to fix their ODR violations. http://crbug.com/456021
       ['OS=="linux"', {
         'ldflags!': [
           '-Wl,--detect-odr-violations',
         ],
       }],
     ],
   }]
 }