Remove Win8 SDK header as input to the win8 check_sdk_patch target.

win8/win8.gyp

 # 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.
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     '../build/win_precompile.gypi',
   ],
   'targets': [
     {
       'target_name': 'check_sdk_patch',
       'type': 'none',
       'variables': {
         'check_sdk_script': '<(DEPTH)/chrome/tools/build/win/check_sdk_patch.py',
         'output_path': '<(INTERMEDIATE_DIR)/check_sdk_patch',
       },
       'actions': [
         {
           'action_name': 'check_sdk_patch_action',
           'inputs': [
             '<(check_sdk_script)',
-            '<(windows_sdk_path)/Include/winrt/asyncinfo.h',
           ],
           'outputs': [
             # This keeps the ninja build happy and provides a slightly helpful
             # error messge if the sdk is missing.
             '<(output_path)'
           ],
           'action': ['python',
                      '<(check_sdk_script)',
                      '<(windows_sdk_path)',
                      '<(output_path)',
                      ],
         },
       ],
     },
   ],
-}
+}