Update several clang warnings after r287092.

third_party/libjingle/libjingle.gyp

 # 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.
 
 {
   'includes': [
     '../../build/win_precompile.gypi',
   ],
   'variables': {
     'enabled_libjingle_device_manager%': 0,
@@ skipping 130 matching lines @@
       'configurations': {
         'Debug': {
           'defines': [
             # TODO(sergeyu): Fix libjingle to use NDEBUG instead of
             # _DEBUG and remove this define. See above as well.
             '_DEBUG',
           ],
         }
       },
     },
+    'variables': {
+      'clang_warning_flags_unset': [
+        # Don't warn about string->bool used in asserts.
+        '-Wstring-conversion',
+      ],
+    },
     'conditions': [
       ['"<(libpeer_target_type)"=="static_library"', {
         'defines': [ 'LIBPEERCONNECTION_LIB=1' ],
       }],
       ['use_openssl==1', {
         'defines': [
           'SSL_USE_OPENSSL',
           'HAVE_OPENSSL_SSL_H',
         ],
         'dependencies': [
@@ skipping 25 matching lines @@
           '../third_party/platformsdk_win7/files/Include',
         ],
         'conditions' : [
           ['target_arch == "ia32"', {
             'defines': [
               '_USE_32BIT_TIME_T',
             ],
           }],
         ],
       }],
-      ['clang == 1', {
-        'xcode_settings': {
-          'WARNING_CFLAGS!': [
-            # Don't warn about string->bool used in asserts.
-            '-Wstring-conversion',
-          ],
-        },
-        'cflags!': [
-          '-Wstring-conversion',
-        ],
-      }],
       ['OS=="linux"', {
         'defines': [
           'LINUX',
         ],
       }],
       ['OS=="mac"', {
         'defines': [
           'OSX',
         ],
       }],
@@ skipping 431 matching lines @@
               # in this directory and not lib.target as will otherwise be
               # the case with make builds.
               'product_dir': '<(PRODUCT_DIR)/lib',
             }],
           ],
         },  # target libpeerconnection
       ],
     }],
   ],
 }