Make `python build/vs_toolchain.py update` mostly work on non-Windows.

win_toolchain/get_toolchain_if_necessary.py

 #!/usr/bin/env python
 # Copyright 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.
 
 """Downloads and unpacks a toolchain for building on Windows. The contents are
 matched by sha1 which will be updated when the toolchain is updated.
 
 Having a toolchain script in depot_tools means that it's not versioned
 directly with the source code. That is, if the toolchain is upgraded, but
@@ skipping 39 matching lines @@
 
 
 def GetFileList(root):
   """Gets a normalized list of files under |root|."""
   assert not os.path.isabs(root)
   assert os.path.normpath(root) == root
   file_list = []
   for base, _, files in os.walk(root):
     paths = [os.path.join(base, f) for f in files]
     file_list.extend(x.lower() for x in paths)
-  return sorted(file_list)
+  return sorted(file_list, key=lambda s: s.replace('/', '\\'))
 
 
 def MakeTimestampsFileName(root):
   return os.path.join(root, '..', '.timestamps')
 
 
 def CalculateHash(root):
   """Calculates the sha1 of the paths to all files in the given |root| and the
   contents of those files, and returns as a hex string."""
   file_list = GetFileList(root)
@@ skipping 15 matching lines @@
   if matches:
     for disk, cached in zip(file_list, timestamps_data['files']):
       if disk != cached[0] or os.stat(disk).st_mtime != cached[1]:
         matches = False
         break
   if matches:
     return timestamps_data['sha1']
 
   digest = hashlib.sha1()
   for path in file_list:
-    digest.update(path)
+    digest.update(str(path).replace('/', '\\'))
     with open(path, 'rb') as f:
       digest.update(f.read())
   return digest.hexdigest()
 
 
 def SaveTimestampsAndHash(root, sha1):
   """Saves timestamps and the final hash to be able to early-out more quickly
   next time."""
   file_list = GetFileList(root)
   timestamps_data = {
@@ skipping 215 matching lines @@
 
   if options.output_json:
     shutil.copyfile(os.path.join(target_dir, '..', 'data.json'),
                     options.output_json)
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())