Fix all -Wnon-virtual-dtor warnings.

webrtc/base/base.gyp

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 {
   'includes': [ '../build/common.gypi', ],
@@ skipping 271 matching lines @@
         'urlencode.h',
         'worker.cc',
         'worker.h',
       ],
       # TODO(henrike): issue 3307, make rtc_base build without disabling
       # these flags.
       'cflags!': [
         '-Wextra',
         '-Wall',
       ],
-      'cflags_cc!': [
-        '-Wnon-virtual-dtor',
-      ],
       'direct_dependent_settings': {
-        'cflags_cc!': [
-          '-Wnon-virtual-dtor',
-        ],
         'defines': [
           'FEATURE_ENABLE_SSL',
           'SSL_USE_OPENSSL',
           'HAVE_OPENSSL_SSL_H',
         ],
       },
       'include_dirs': [
         '../../third_party/jsoncpp/overrides/include',
         '../../third_party/jsoncpp/source/include',
       ],
@@ skipping 299 matching lines @@
     },
     {
      'target_name': 'gtest_prod',
       'type': 'static_library',
       'sources': [
         'gtest_prod_util.h',
       ],
     },
   ],
 }