Update existing uses of /wd4267 to use the GN config

ui/message_center/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 
 component("message_center") {
   deps = [
     "//base",
     "//base:i18n",
     "//base/third_party/dynamic_annotations",
     "//skia",
     "//ui/accessibility",
     "//ui/base",
     "//ui/events",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/native_theme",
     "//ui/resources",
     "//ui/strings",
     "//url",
   ]
 
+  # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
+  configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
+
   defines = [ "MESSAGE_CENTER_IMPLEMENTATION" ]
 
   if (enable_notifications && !is_android) {
     sources = [
       "cocoa/notification_controller.h",
       "cocoa/notification_controller.mm",
       "cocoa/opaque_views.h",
       "cocoa/opaque_views.mm",
       "cocoa/popup_collection.h",
       "cocoa/popup_collection.mm",
@@ skipping 31 matching lines @@
       "notification_delegate.h",
       "notification_list.cc",
       "notification_list.h",
       "notification_types.cc",
       "notification_types.h",
       "notifier_settings.cc",
       "notifier_settings.h",
     ]
 
     if (is_win) {
-      # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
-      cflags = [ "/wd4267" ]
       deps += [ "//ui/aura" ]
     }
 
     # On Mac, toolkit-views builds still use the Cocoa UI. Keep this in sync
     # with message_center_unittests below.
     if (toolkit_views && !is_mac) {
       sources += [
         "views/bounded_label.cc",
         "views/bounded_label.h",
         "views/constants.h",
@@ skipping 141 matching lines @@
           # Compositor is needed by message_center_view_unittest.cc and for the
           # fonts used by bounded_label_unittest.cc.
           "//ui/compositor",
           "//ui/views",
           "//ui/views:test_support",
         ]
       }
     }  # enable_notifications && !is_android
   }
 }