clang/win: Take another stab at building with -Wunused-private-field.

third_party/cld_2/cld_2.gyp

 # Copyright 2013 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.
 
 # MAINTAINERS:
 # See the BUILD.gn file for more extensive comments and documentation. This
 # .gyp file exists only for compatibility with gyp. The variables defined below
 # are used in equivalent targets in BUILD.GN.
 
 {
@@ skipping 160 matching lines @@
           'sources+': ['<@(cld2_data_smallest_sources)']
         }],
         ['cld2_table_size==2', {
           'sources+': ['<@(cld2_data_largest_sources)']
         }],
       ],
       'variables': {
         'clang_warning_flags': [
           # The generated files don't have braces around subobject initializers.
           '-Wno-missing-braces',
-          # cld_2 contains unused private fields.
+          # cld_2 contains unused private fields,
+          # https://code.google.com/p/cld2/issues/detail?id=37
           '-Wno-unused-private-field',
         ],
       },
     },
 
     {
       # GN version: //third_party/cld_2:cld2_dynamic
       'target_name': 'cld2_dynamic',
       'type': 'static_library',
       'conditions': [
         ['OS=="win"', {
           'msvs_disabled_warnings': [4267], # size_t -> int conversion.
         }],
       ],
       'include_dirs': [
         'src/internal',
         'src/public',
       ],
       'sources': [
         '<@(cld2_core_sources)',
         '<@(cld2_core_impl_sources)',
         '<@(cld2_dynamic_data_loader_sources)',
       ],
       'defines': ['CLD2_DYNAMIC_MODE'],
+      'variables': {
+        'clang_warning_flags': [
+          # cld_2 contains unused private fields,
+          # https://code.google.com/p/cld2/issues/detail?id=37
+          '-Wno-unused-private-field',
+        ],
+      },
     },
   ],
 }