Remove deprecated unittest_helper classes.

testing_support/git/unittest_helpers.py

 # Copyright 2014 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 testing_support import auto_stub
 
 from testing_support.git.repo import GitRepo
 from testing_support.git.schema import GitRepoSchema
 
 
@@ skipping 29 matching lines @@
     # derived test case class.
     self.r_schema = GitRepoSchema(self.REPO_SCHEMA, self.getRepoContent)
     self.repo = GitRepo(self.r_schema)
     self.repo.git('checkout', '-f', self.repo.last_commit)
 
   def tearDown(self):
     try:
       self.repo.nuke()
     finally:
       super(GitRepoTestBase, self).tearDown()
-
-
-# The read-only version used to set up and tear down repo on a setUpClass basis,
-# and the read-write version used to do it on a setUp basis. This is no longer
-# the case. Keep the names around, but they're deprecated.
-GitRepoReadWriteTestBase = GitRepoTestBase
-GitRepoReadOnlyTestBase = GitRepoTestBase
-
-# Additionally, there was a schema-only version, but it was pretty useless
-GitRepoSchemaTestBase = GitRepoTestBase