Docserver: there is only one.

chrome/common/extensions/docs/server2/test_patcher.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.
 
 from future import Future
 from patcher import Patcher
 
 class TestPatcher(Patcher):
   def __init__(self, version, patched_files, patch_data, assert_binary=False):
     self._version = version
@@ skipping 15 matching lines @@
 
   def Apply(self, paths, file_system, binary, version=None):
     if self._assert_binary:
       assert binary
     self.apply_count += 1
     try:
       return Future(value=dict((path, self._patch_data[path])
                                for path in paths))
     except KeyError:
       raise FileNotFoundError('One of %s is deleted in the patch.' % paths)
+
+  def GetIdentity(self):
+    return self.__class__.__name__