Fix ui/gl and gpu target building with GN on Windows.

build/toolchain/win/setup_toolchain.py

 # 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.
 
 import errno
 import os
 import re
 import subprocess
 import sys
 
@@ skipping 117 matching lines @@
     variables, _ = popen.communicate()
     env = _ExtractImportantEnvironment(variables)
     env['PATH'] = runtime_dirs + ';' + env['PATH']
 
     if arch == cpu_arch:
       for path in env['PATH'].split(os.pathsep):
         if os.path.exists(os.path.join(path, 'cl.exe')):
           vc_bin_dir = os.path.realpath(path)
           break
 
-    # TODO(scottmg|thakis|dpranke): Is there an equivalent to
-    # msvs_system_include_dirs that we need to inject into INCLUDE here?
+    # The Windows SDK include directories must be first. They both have a sal.h,
+    # and the SDK one is newer and the SDK uses some newer features from it not
+    # present in the Visual Studio one.
 
+    if win_sdk_path:
+      additional_includes = ('{sdk_dir}\\Include\\shared;' +
+                             '{sdk_dir}\\Include\\um;' +
+                             '{sdk_dir}\\Include\\winrt;').format(
+                                  sdk_dir=win_sdk_path)
+      env['INCLUDE'] = additional_includes + env['INCLUDE']
     env_block = _FormatAsEnvironmentBlock(env)
     with open('environment.' + arch, 'wb') as f:
       f.write(env_block)
 
   assert vc_bin_dir
   print 'vc_bin_dir = "%s"' % vc_bin_dir
 
 
 if __name__ == '__main__':
   main()