Update out-of-date references to fake_repository.py

mojo/tools/testing/mojom_fetcher/mojom_fetcher_tests.py

 #!/usr/bin/env python
 # Copyright 2015 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 io
 import os
 import sys
 import unittest
 
 sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)),
                                 "..", "..", "..", "public", "tools",
                                 "mojom_fetcher"))
 sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)),
                                 "..", "..", "..", "public", "tools",
                                 "mojom_fetcher", "pylib"))
 sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)),
                                 "..", "..", "..", "public", "tools",
                                 "bindings", "pylib"))
 
 from mojom_fetcher import UrlRewriter, UrlRewriterException, MojomFetcher
 
 # Fake repository for testing
-from fake_repository import FakeRepository
+from fakes import FakeRepository
 
 class TestUrlRewriter(unittest.TestCase):
   def test_no_transitive(self):
     rules = {"foo.com": "bar.com/foo", "bar.com": "baz.com"}
     try:
       UrlRewriter(rules)
       self.fail()
     except UrlRewriterException:
       # This is expected
       pass
@@ skipping 64 matching lines @@
                        "https://services.fiz.org/foo/bar.mojom"],
                       self.fetcher.downloaded_urls)
 
 if __name__ == '__main__':
   loader = unittest.defaultTestLoader
   runner = unittest.TextTestRunner()
   directory = os.path.dirname(os.path.abspath(__file__))
   suite = loader.discover(directory, '*_tests.py')
   runner.run(suite)