Use ~/.gyp/include.gypi in GN build.

build/gyp_chromium

 #!/usr/bin/env python
 
 # Copyright (c) 2012 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.
 
 # This script is wrapper for Chromium that adds some support for how GYP
 # is invoked by Chromium beyond what can be done in the gclient hooks.
 
 import glob
@@ skipping 111 matching lines @@
       cmdline_input_items += [sys.argv[i + 1]]
   cmdline_items = ProcessGypDefinesItems(cmdline_input_items)
 
   return dict(supp_items + env_items + cmdline_items)
 
 
 def GetArgsStringForGN(supplemental_files):
   """Returns the args to pass to GN.
   Based on a subset of the GYP variables that have been rewritten a bit."""
 
+  # Find the .gyp directory in the user's home directory.
+  home_dot_gyp = os.environ.get('GYP_CONFIG_DIR', None)
+  if home_dot_gyp:
+    home_dot_gyp = os.path.expanduser(home_dot_gyp)
+  if not home_dot_gyp:
+    home_vars = ['HOME']
+    if sys.platform in ('cygwin', 'win32'):
+      home_vars.append('USERPROFILE')
+    for home_var in home_vars:
+      home = os.getenv(home_var)
+      if home != None:
+        home_dot_gyp = os.path.join(home, '.gyp')
+        if not os.path.exists(home_dot_gyp):
+          home_dot_gyp = None
+        else:
+          break
+
+  if home_dot_gyp:
+    include_gypi = os.path.join(home_dot_gyp, "include.gypi")
+    if os.path.exists(include_gypi):
+      supplemental_files += [include_gypi]
+
   vars_dict = GetGypVarsForGN(supplemental_files)
   gn_args = ''
 
   # Note: These are the additional flags passed to various builds by builders
   # on the main waterfall. We'll probably need to add these at some point:
   #   mac_strip_release=1         http://crbug.com/330301
   #   linux_dump_symbols=0        http://crbug.com/330300
   #   host_os=linux  Probably can skip, GN knows the host OS.
   #   order_text_section=<path>   http://crbug.com/330299
   #   chromium_win_pch=0          http://crbug.com/297678
@@ skipping 231 matching lines @@
   if not RunGN(supplemental_includes):
     sys.exit(1)
   args.extend(
       ['-I' + i for i in additional_include_files(supplemental_includes, args)])
 
   print 'Updating projects from gyp files...'
   sys.stdout.flush()
 
   # Off we go...
   sys.exit(gyp.main(args))