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

tools/telemetry/telemetry/record_wpr.py

 # Copyright 2012 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 argparse
 import logging
 import sys
 
 from telemetry import benchmark
 from telemetry import story
-from telemetry.core import discover
 from telemetry.core import util
 from telemetry.internal.browser import browser_options
 from telemetry.internal.results import results_options
 from telemetry.internal import story_runner
 from telemetry.internal.util import command_line
 from telemetry.page import page_test
+from telemetry.util import classes_util
 from telemetry.util import wpr_modes
 
 
 class RecorderPageTest(page_test.PageTest):
   def __init__(self):
     super(RecorderPageTest, self).__init__()
     self.page_test = None
 
   def CustomizeBrowserOptions(self, options):
     if self.page_test:
@@ skipping 36 matching lines @@
 
 def _GetSubclasses(base_dir, cls):
   """Returns all subclasses of |cls| in |base_dir|.
 
   Args:
     cls: a class
 
   Returns:
     dict of {underscored_class_name: benchmark class}
   """
-  return discover.DiscoverClasses(base_dir, base_dir, cls,
-                                  index_by_class_name=True)
+  return classes_util.DiscoverClassesByClassName(base_dir, base_dir, cls)
 
 
 def _MaybeGetInstanceOfClass(target, base_dir, cls):
   if isinstance(target, cls):
     return target
-  classes = _GetSubclasses(base_dir, cls)
-  return classes[target]() if target in classes else None
+  return classes_util.MaybeGetInstanceOfClass(target, base_dir, base_dir, cls)
 
 
 def _PrintAllImpl(all_items, item_name, output_stream):
   output_stream.write('Available %s\' names with descriptions:\n' % item_name)
   keys = sorted(all_items.keys())
   key_description = [(k, all_items[k].Description()) for k in keys]
   _PrintPairs(key_description, output_stream)
   output_stream.write('\n')
 
 
@@ skipping 171 matching lines @@
     return 0
 
   # TODO(nednguyen): update WprRecorder so that it handles the difference
   # between recording a benchmark vs recording a story better based on
   # the distinction between args.benchmark & args.story
   wpr_recorder = WprRecorder(base_dir, target, extra_args)
   results = wpr_recorder.CreateResults()
   wpr_recorder.Record(results)
   wpr_recorder.HandleResults(results, args.upload)
   return min(255, len(results.failures))