Docserver: Fix invalid path usage in CloudStorageFileSystem.

chrome/common/extensions/docs/server2/content_provider.py

 # 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.
 
 import mimetypes
 import posixpath
 
 from compiled_file_system import SingleFile
 from directory_zipper import DirectoryZipper
 from docs_server_utils import ToUnicode
 from file_system import FileNotFoundError
 from future import Gettable, Future
 from path_canonicalizer import PathCanonicalizer
-from path_util import AssertIsValid, ToDirectory
+from path_util import AssertIsValid, Join, ToDirectory
 from special_paths import SITE_VERIFICATION_FILE
 from third_party.handlebar import Handlebar
 from third_party.markdown import markdown
 
 
 _MIMETYPE_OVERRIDES = {
   # SVG is not supported by mimetypes.guess_type on AppEngine.
   '.svg': 'image/svg+xml',
 }
 
@@ skipping 121 matching lines @@
         if self.file_system.Exists(path + default_ext).Get():
           path += default_ext
           break
 
     return self._content_cache.GetFromFile(path)
 
   def Cron(self):
     futures = [self._path_canonicalizer.Cron()]
     for root, _, files in self.file_system.Walk(''):
       for f in files:
-        futures.append(self.GetContentAndType(posixpath.join(root, f)))
+        futures.append(self.GetContentAndType(Join(root, f)))
         # Also cache the extension-less version of the file if needed.
         base, ext = posixpath.splitext(f)
         if f != SITE_VERIFICATION_FILE and ext in self._default_extensions:
-          futures.append(self.GetContentAndType(posixpath.join(root, base)))
+          futures.append(self.GetContentAndType(Join(root, base)))
       # TODO(kalman): Cache .zip files for each directory (if supported).
     return Future(delegate=Gettable(lambda: [f.Get() for f in futures]))
 
   def __repr__(self):
     return 'ContentProvider of <%s>' % repr(self.file_system)