Update existing uses of /wd4267 to use the GN config

third_party/libpng/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.
 
 config("libpng_config") {
   include_dirs = [ "." ]
 
   defines = [
     "CHROME_PNG_WRITE_SUPPORT",
     "PNG_USER_CONFIG",
@@ skipping 34 matching lines @@
     "pngvcrd.c",
     "pngwio.c",
     "pngwrite.c",
     "pngwtran.c",
     "pngwutil.c",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
 
-  if (is_win) {
-    cflags = [ "/wd4267" ]  # TODO(jschuh): http://crbug.com/167187
-
-    if (component_mode == "shared_library") {
-      defines = [ "PNG_BUILD_DLL" ]
-    }
+  if (is_win && is_component_build) {
+    defines = [ "PNG_BUILD_DLL" ]
   }
 
   public_configs = [ ":libpng_config" ]
 
   public_deps = [
     "//third_party/zlib",
   ]
 }
 
 if (is_win) {
   component("libpng") {
     public_deps = [
       ":libpng_sources",
     ]
   }
 } else {
   group("libpng") {
     public_deps = [
       ":libpng_sources",
     ]
   }
 }