Fix MockFileSystem.walk and add test.

third_party/WebKit/Tools/Scripts/webkitpy/w3c/test_importer.py

 # Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 #
 # 1. Redistributions of source code must retain the above
 #    copyright notice, this list of conditions and the following
 #    disclaimer.
 # 2. Redistributions in binary form must reproduce the above
@@ skipping 207 matching lines @@
                     if not self.options.dry_run and self.import_in_place:
                         _log.info("  pruning %s" % path_base)
                         self.filesystem.remove(path_full)
                         continue
                     else:
                         continue
                 # FIXME: This block should really be a separate function, but the early-continues make that difficult.
 
                 if filename.startswith('.') or filename.endswith('.pl'):
                     continue  # For some reason the w3c repo contains random perl scripts we don't care about.
+                if filename == 'OWNERS':
+                    continue  # These files fail our presubmits
+
 
                 fullpath = self.filesystem.join(root, filename)
 
                 mimetype = mimetypes.guess_type(fullpath)
                 if not 'html' in str(mimetype[0]) and not 'application/xhtml+xml' in str(mimetype[0]) and not 'application/xml' in str(mimetype[0]):
                     copy_list.append({'src': fullpath, 'dest': filename})
                     continue
 
                 if self.filesystem.basename(root) in DIRS_TO_INCLUDE:
                     copy_list.append({'src': fullpath, 'dest': filename})
@@ skipping 177 matching lines @@
         """ Creates a destination directory that mirrors that of the source directory """
 
         new_subpath = self.dir_to_import[len(self.top_of_repo):]
 
         destination_directory = self.filesystem.join(self.destination_directory, new_subpath)
 
         if not self.filesystem.exists(destination_directory):
             self.filesystem.maybe_make_directory(destination_directory)
 
         _log.info('Tests will be imported into: %s', destination_directory)