GN: Replace Windows suppressions of warning 4267 with config.

webrtc/modules/media_file/BUILD.gn

Index: webrtc/modules/media_file/BUILD.gn
diff --git a/webrtc/modules/media_file/BUILD.gn b/webrtc/modules/media_file/BUILD.gn
index 2a4be728f3d3fd9e8bc8db2dff30bd2b9e5ae4b7..84f094fd1159f774de5f8ce71229ae1ed3e120c2 100644
--- a/webrtc/modules/media_file/BUILD.gn
+++ b/webrtc/modules/media_file/BUILD.gn
@@ -22,19 +22,15 @@ source_set("media_file") {
     "media_file_utility.h",
   ]
 
-  if (is_win) {
-    cflags = [
-      # TODO(jschuh): Bug 1348: fix this warning.
-      "/wd4267",  # size_t to int truncations
-    ]
-  }
-
   configs += [ "../..:common_config" ]
   public_configs = [
     "../..:common_inherited_config",
     ":media_file_config",
   ]
 
+  # TODO(jschuh): Bug 1348: fix this warning.
+  configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
+
   if (is_clang) {
     # Suppress warnings from Chrome's Clang plugins.
     # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
@@ -43,7 +39,7 @@ source_set("media_file") {
 
   deps = [
     "../..:webrtc_common",
-    "../../system_wrappers",
     "../../common_audio",
+    "../../system_wrappers",
   ]
 }