Add -Wno-unused-functions to the clang/mac config, to match clang/linux.

build/common.gypi

 # Copyright (c) 2010 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': {
     # .gyp files or targets should set chromium_code to 1 if they build
@@ skipping 1258 matching lines @@
           ],
           'conditions': [
             ['chromium_mac_pch', {'GCC_PRECOMPILE_PREFIX_HEADER': 'YES'},
                                  {'GCC_PRECOMPILE_PREFIX_HEADER': 'NO'}
             ],
             ['clang==1', {
               'WARNING_CFLAGS': [
                 # Don't die on dtoa code that uses a char as an array index.
                 # This is required solely for base/third_party/dmg_fp/dtoa.cc.
                 '-Wno-char-subscripts',
+                # Clang spots more unused functions.
+                '-Wno-unused-function',
                 # Survive EXPECT_EQ(unnamed_enum, unsigned int) -- see
                 # http://code.google.com/p/googletest/source/detail?r=446 .
                 # TODO(thakis): Use -isystem instead (http://crbug.com/58751 ).
                 '-Wno-unnamed-type-template-args',
               ],
             }],
           ],
         },
         'target_conditions': [
           ['_type!="static_library"', {
@@ skipping 238 matching lines @@
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }
 
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 # tab-width:2
 # indent-tabs-mode:nil
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