Add -Wno-deprecated-declarations on iOS in preparation of changing SDK.

ios/crnet/test/crnet_test.gyp

 # Copyright 2015 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': {
     'chromium_code': 1,
   },
   'targets': [],
   'conditions': [
@@ skipping 12 matching lines @@
           'sources': [
             'crnet_http_tests.mm',
             'crnet_test_runner.mm',
           ],
           'include_dirs': [
             '../../..',
             '..',
           ],
           'link_settings': {
           },
+          # TODO(crbug.com/571217): Disabled warning-as-error option until
+          # this bug is fixed.
+          'xcode_settings': {
+            'WARNING_CFLAGS': [
+              '-Wno-deprecated-declarations',
+            ],
+          },
         },
       ],
     }],
   ],
 }