Explicitly pass -Wno-unused-function to the targets that need it.

third_party/snappy/snappy.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.
 
 {
 'variables': {
     'conditions': [
       # Define an "os_include" variable that points at the OS-specific generated
       # headers.  These were generated by running the configure script offline.
       ['os_posix == 1 and OS != "mac"', {
@@ skipping 13 matching lines @@
         'src',
         '../..',
       ],
       'direct_dependent_settings': {
         'include_dirs': [
           '<(os_include)',
           'src',
         ],
       },
       'variables': {
+        'clang_warning_flags': [
+           # ComputeTable is unused,
+           # https://code.google.com/p/snappy/issues/detail?id=96
+           '-Wno-unused-function',
+         ],
         'clang_warning_flags_unset': [
           # snappy-stubs-internal.h unapologetically has: using namespace std
           # https://code.google.com/p/snappy/issues/detail?id=70
           '-Wheader-hygiene',
         ],
       },
       'sources': [
         'src/snappy-internal.h',
         'src/snappy-sinksource.cc',
         'src/snappy-sinksource.h',
@@ skipping 46 matching lines @@
             # TODO(tfarina): Only Mac and Linux has the generated config.h for
             # now. Generate the config.h for Windows too and enable this there
             # as well.
             'HAVE_CONFIG_H=1',
           ],
         }],
       ],
     },
   ],
 }