GN: Replace Windows suppressions of warning 4267 with config.

webrtc/system_wrappers/BUILD.gn

 # 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.
 
 import("//build/config/android/config.gni")
 import("../build/webrtc.gni")
@@ skipping 103 matching lines @@
 
   if (is_linux || is_android) {
     sources += [ "source/atomic32_non_darwin_unix.cc" ]
   }
 
   if (is_ios || is_mac) {
     defines += [ "WEBRTC_THREAD_RR" ]
     sources += [ "source/atomic32_darwin.cc" ]
   }
 
+  # TODO(jschuh): Bug 1348: fix this warning.
+  configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
+
   if (is_win) {
     libs += [ "winmm.lib" ]
 
-    cflags = [
-      "/wd4267",  # size_t to int truncation.
-      "/wd4334",  # Ignore warning on shift operator promotion.
-    ]
+    cflags = [ "/wd4334" ]  # Ignore warning on shift operator promotion.
   }
 
   deps += [ "../base:rtc_base_approved" ]
 }
 
 source_set("field_trial_default") {
   sources = [
     "include/field_trial_default.h",
     "source/field_trial_default.cc",
   ]
@@ skipping 40 matching lines @@
 if (is_linux) {
   source_set("cpu_features_linux") {
     sources = [
       "source/cpu_features_linux.c",
     ]
 
     configs += [ "..:common_config" ]
     public_configs = [ "..:common_inherited_config" ]
   }
 }