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

tools/perf/measurements/measurement_smoke_test.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.
 
 import logging
 import optparse
 import os
 import unittest
 
 from telemetry import benchmark as benchmark_module
+from telemetry.core import discover
 from telemetry.internal.browser import browser_options
 from telemetry.page import page_test
 from telemetry.testing import options_for_unittests
-from telemetry.util import classes_util
 from telemetry.web_perf import timeline_based_measurement
 
 
 def _GetAllPossiblePageTestInstances():
   page_test_instances = []
   measurements_dir = os.path.dirname(__file__)
   top_level_dir = os.path.dirname(measurements_dir)
   benchmarks_dir = os.path.join(top_level_dir, 'benchmarks')
 
   # Get all page test instances from measurement classes that are directly
   # constructable
-  all_measurement_classes = classes_util.DiscoverClasses(
+  all_measurement_classes = discover.DiscoverClasses(
       measurements_dir, top_level_dir, page_test.PageTest,
-      directly_constructable=True)
+      index_by_class_name=True, directly_constructable=True).values()
   for measurement_class in all_measurement_classes:
     page_test_instances.append(measurement_class())
 
-  all_benchmarks_classes = classes_util.DiscoverClasses(
-      benchmarks_dir, top_level_dir, benchmark_module.Benchmark)
+  all_benchmarks_classes = discover.DiscoverClasses(
+      benchmarks_dir, top_level_dir, benchmark_module.Benchmark).values()
 
   # Get all page test instances from defined benchmarks.
   # Note: since this depends on the command line options, there is no guaranteed
   # that this will generate all possible page test instances but it's worth
   # enough for smoke test purpose.
   for benchmark_class in all_benchmarks_classes:
     options = options_for_unittests.GetCopy()
     parser = optparse.OptionParser()
     browser_options.BrowserOptions.AddCommandLineArgs(parser)
     try:
       benchmark_class.AddCommandLineArgs(parser)
       benchmark_module.AddCommandLineArgs(parser)
       benchmark_class.SetArgumentDefaults(parser)
     except Exception:
       logging.error('Exception raised when processing benchmark %s'
           % benchmark_class)
       raise
     options.MergeDefaultValues(parser.get_default_values())
     pt = benchmark_class().CreatePageTest(options)
     if not isinstance(pt, timeline_based_measurement.TimelineBasedMeasurement):
       page_test_instances.append(pt)
 
   return page_test_instances
 
 
 class MeasurementSmokeTest(unittest.TestCase):
   # Simple smoke test to make sure that all page_test are constructible.
   def testAllMeasurementInstance(self):
     _GetAllPossiblePageTestInstances()