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

tools/perf/benchmarks/benchmark_smoke_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.
 
 """Run the first page of one benchmark for every module.
 
 Only benchmarks that have a composable measurement are included.
 Ideally this test would be comprehensive, however, running one page
 of every benchmark would run impractically long.
 """
@@ skipping 82 matching lines @@
 }
 
 
 def load_tests(loader, standard_tests, pattern):
   del loader, standard_tests, pattern  # unused
   suite = progress_reporter.TestSuite()
 
   benchmarks_dir = os.path.dirname(__file__)
   top_level_dir = os.path.dirname(benchmarks_dir)
 
-  # Using the default of |index_by_class_name=False| means that if a module
-  # has multiple benchmarks, only the last one is returned.
+  # Using the default of |one_class_per_module=True| means that if a module
+  # has multiple benchmarks, only the first one is returned.
   all_benchmarks = discover.DiscoverClasses(
       benchmarks_dir, top_level_dir, benchmark_module.Benchmark,
-      index_by_class_name=False).values()
+      one_class_per_module=True)
   for benchmark in all_benchmarks:
     if sys.modules[benchmark.__module__] in _BLACK_LIST_TEST_MODULES:
       continue
     # TODO(tonyg): Smoke doesn't work with session_restore yet.
     if (benchmark.Name().startswith('session_restore') or
         benchmark.Name().startswith('skpicture_printer')):
       continue
 
     if hasattr(benchmark, 'generated_profile_archive'):
       # We'd like to test these, but don't know how yet.
@@ skipping 26 matching lines @@
 
     # Disable some tests on android platform only.
     if sys.modules[benchmark.__module__] in _ANDROID_BLACK_LIST_MODULES:
       method._disabled_strings.append('android')
 
     setattr(BenchmarkSmokeTest, benchmark.Name(), method)
 
     suite.addTest(BenchmarkSmokeTest(benchmark.Name()))
 
   return suite