Implemented AddAllocWithZoneMethod to override allocWithZone: on demand.

ios/web/ios_web_unittests.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.
 {
   'variables': {
     'chromium_code': 1,
    },
   'targets': [
     {
       'target_name': 'ios_web_unittests',
       'type': '<(gtest_target_type)',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../base/base.gyp:run_all_unittests',
         '../../base/base.gyp:test_support_base',
         '../../testing/gmock.gyp:gmock',
         '../../testing/gtest.gyp:gtest',
         'ios_web.gyp:ios_web',
         'ios_web.gyp:test_support_ios_web',
       ],
       'sources': [
+        'alloc_with_zone_interceptor_unittest.mm',
         'browser_state_unittest.cc',
         'crw_network_activity_indicator_manager_unittest.mm',
         'history_state_util_unittest.mm',
         'navigation/navigation_item_impl_unittest.mm',
         'navigation/nscoder_util_unittest.mm',
         'net/cert_policy_unittest.cc',
         'net/request_group_util_unittest.mm',
         'public/referrer_util_unittest.cc',
         'string_util_unittest.cc',
         'url_scheme_util_unittest.mm',
         'url_util_unittest.cc',
         'weak_nsobject_counter_unittest.mm',
       ],
     },
   ],
 }