Remove FileUtilProxy from the untrusted (NaCl) build of base.

base/base.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.
 
 {
   'target_defaults': {
     'variables': {
       'base_target': 0,
     },
     'target_conditions': [
@@ skipping 683 matching lines @@
             'sources!': [
                'allocator/type_profiler_control.cc',
                'allocator/type_profiler_control.h',
                'base_paths.cc',
                'cpu.cc',
                'debug/stack_trace_posix.cc',
                'file_util.cc',
                'file_util_posix.cc',
                'files/file_enumerator_posix.cc',
                'files/file_path_watcher_kqueue.cc',
+               'files/file_util_proxy.cc',
                'memory/shared_memory_posix.cc',
                'native_library_posix.cc',
                'path_service.cc',
                'posix/unix_domain_socket_linux.cc',
                'process/kill_posix.cc',
                'process/launch_posix.cc',
                'process/process_metrics_posix.cc',
                'process/process_posix.cc',
                'rand_util_posix.cc',
                'scoped_native_library.cc',
@@ skipping 163 matching lines @@
           ['<(use_system_nspr)==1 and >(nacl_untrusted_build)==0', {
             'sources/': [
               ['exclude', '^third_party/nspr/'],
             ],
           }],
         ],
       }],
     ],
   },
 }