Update from https://crrev.com/304121

third_party/libxml/BUILD.gn

 # Copyright (c) 2013 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.
 
 # Define an "os_include" variable that points at the OS-specific generated
 # headers.  These were generated by running the configure script offline.
 if (is_linux || is_android) {
   os_include = "linux"
 } else if (is_mac || is_ios) {
   os_include = "mac"
@@ skipping 135 matching lines @@
   public_deps = [
     "//third_party/icu:icuuc",
   ]
   deps = [
     "//third_party/zlib",
   ]
 
   if (is_win) {
     cflags_c = [
       "/wd4101",  # Unreferenced local variable.
-      "/wd4267",  # TODO(jschuh): crbug.com/167187 size_t to int truncations.
     ]
   } else if (is_mac || is_android) {
     # http://www.xmlsoft.org/threads.html says that this is required when using
     # libxml from several threads, which can possibly happen in chrome. On
     # linux, this is picked up by transitivity from pkg-config output from
     # build/linux/system.gyp.
     defines = [ "_REENTRANT" ]
   }
 
   if (is_clang) {
@@ skipping 12 matching lines @@
       # threads.c attempts to forward declare a pthread_equal which doesn't
       # match the prototype in pthreads.h
       "-Wno-ignored-attributes",
     ]
   }
 
   include_dirs = [
     "$os_include",
   ]
 }