Update Chomium's build files to work w/ latest GN binaries.

third_party/harfbuzz-ng/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/linux/pkg_config.gni")
 
 # The GYP build supports system harfbuzz for non-official builds when using
 # pangoft2 1.31.0 or greater (which pulls it in).
 # TODO(brettw) we can consider doing this as well, although the benefit is
 # unclear and requires shelling out to a script to check the version.
@@ skipping 10 matching lines @@
     # control as well.
     use_system_harfbuzz = exec_script(pkg_config_script,
                                       pkg_config_args + [
                                             "--atleast-version=1.31.0",
                                             "pangoft2",
                                           ],
                                       "value")
   } else {
     use_system_harfbuzz = false
   }
-  if (is_linux && cpu_arch == "arm" && !is_chromeos) {
+  if (is_linux && current_cpu == "arm" && !is_chromeos) {
     # Override use_system_harfbuzz for ARM cross compiling so system
     # harfbuzz is not used because the corresponding package is not
     # available.
     use_system_harfbuzz = false
   }
 }
 
 if (use_system_harfbuzz) {
   import("//build/config/linux/pkg_config.gni")
   pkg_config("harfbuzz_pkgconfig") {
@@ skipping 126 matching lines @@
     }
     if (is_mac) {
       sources += [
         "src/hb-coretext.cc",
         "src/hb-coretext.h",
       ]
       defines += [ "HAVE_CORETEXT" ]
     }
   }
 }