Fixing check_orphan_headers on Windows

tools_webrtc/presubmit_checks_lib/check_orphan_headers.py

 #!/usr/bin/env python
 # Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import os
 import re
+import string
 
 
 # TARGET_RE matches a GN target, and extracts the target name and the contents.
 TARGET_RE = re.compile(r'(?P<indent>\s*)\w+\("(?P<target_name>\w+)"\) {'
                        r'(?P<target_contents>.*?)'
                        r'(?P=indent)}',
                        re.MULTILINE | re.DOTALL)
 
 # SOURCES_RE matches a block of sources inside a GN target.
 SOURCES_RE = re.compile(
@@ skipping 83 matching lines @@
     The set contains absolute paths.
   """
   headers_in_sources = set([])
   for target_match in TARGET_RE.finditer(file_content):
     target_contents = target_match.group('target_contents')
     for sources_match in SOURCES_RE.finditer(target_contents):
       sources = sources_match.group('sources')
       for source_file_match in SOURCE_FILE_RE.finditer(sources):
         source_file = source_file_match.group('source_file')
         if source_file.endswith('.h'):
-          headers_in_sources.add(os.path.join(target_abs_path, source_file))
+          source_file_tokens = string.split(source_file, '/')
+          # pylint: disable=star-args
+          headers_in_sources.add(os.path.join(target_abs_path,
+                                              *source_file_tokens))
   return headers_in_sources