Update existing uses of /wd4267 to use the GN config

ui/aura/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/ui.gni")
 import("//testing/test.gni")
 
 component("aura") {
   sources = [
     "../wm/public/activation_change_observer.cc",
@@ skipping 158 matching lines @@
     "test/test_window_tree_client.h",
     "test/test_windows.cc",
     "test/test_windows.h",
     "test/ui_controls_factory_aura.h",
     "test/window_event_dispatcher_test_api.cc",
     "test/window_event_dispatcher_test_api.h",
     "test/window_test_api.cc",
     "test/window_test_api.h",
   ]
 
+  # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
+  configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
+
   public_deps = [
     ":aura",
   ]
   deps = [
     "//skia",
     "//testing/gtest",
     "//ui/base:test_support",
     "//ui/compositor:test_support",
     "//ui/events",
     "//ui/events:events_base",
     "//ui/events:test_support",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/wm",
   ]
 
   if (is_win) {
     sources += [ "test/ui_controls_factory_aurawin.cc" ]
-
-    cflags = [ "/wd4267" ]  # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   }
 
   if (use_x11) {
     sources += [
       "test/ui_controls_factory_aurax11.cc",
       "test/x11_event_sender.cc",
       "test/x11_event_sender.h",
     ]
 
     deps += [ "//ui/gfx/x" ]
@@ skipping 86 matching lines @@
       "//ui/gfx",
       "//ui/gfx/geometry",
       "//ui/gl",
     ]
 
     if (is_linux) {
       deps += [ "//third_party/mesa" ]
     }
   }
 }