Revert of Create classes_util API, change discover to return a list instead of a dict.

tools/perf/benchmarks/benchmark_unittest.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.
 
 """For all the benchmarks that set options, test that the options are valid."""
 
 from collections import defaultdict
 import os
 import unittest
 
 from core import perf_benchmark
 
 from telemetry import benchmark as benchmark_module
+from telemetry.core import discover
 from telemetry.internal.browser import browser_options
 from telemetry.testing import progress_reporter
-from telemetry.util import classes_util
 
 
 def _GetPerfDir(*subdirs):
   perf_dir = os.path.dirname(os.path.dirname(__file__))
   return os.path.join(perf_dir, *subdirs)
 
 
 def _GetAllPerfBenchmarks():
-  return classes_util.DiscoverClasses(
-      _GetPerfDir('benchmarks'), _GetPerfDir(), benchmark_module.Benchmark)
+  return discover.DiscoverClasses(
+      _GetPerfDir('benchmarks'), _GetPerfDir(), benchmark_module.Benchmark,
+      index_by_class_name=True).values()
 
 def _BenchmarkOptionsTestGenerator(benchmark):
   def testBenchmarkOptions(self):  # pylint: disable=W0613
     """Invalid options will raise benchmark.InvalidOptionsError."""
     options = browser_options.BrowserFinderOptions()
     parser = options.CreateParser()
     benchmark.AddCommandLineArgs(parser)
     benchmark_module.AddCommandLineArgs(parser)
     benchmark.SetArgumentDefaults(parser)
   return testBenchmarkOptions
@@ skipping 39 matching lines @@
     suite.addTest(BenchmarkOptionsTest(benchmark.Name()))
   suite.addTest(TestNoBenchmarkNamesDuplication())
   suite.addTest(TestNoOverrideCustomizeBrowserOptions())
 
 
 def load_tests(loader, standard_tests, pattern):
   del loader, standard_tests, pattern  # unused
   suite = progress_reporter.TestSuite()
   _AddBenchmarkOptionsTests(suite)
   return suite