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

tools/telemetry/telemetry/internal/util/find_dependencies.py

Index: tools/telemetry/telemetry/internal/util/find_dependencies.py
diff --git a/tools/telemetry/telemetry/internal/util/find_dependencies.py b/tools/telemetry/telemetry/internal/util/find_dependencies.py
index 6f40196fb2faee58fc37d502635fe853e576645b..b9592449f0d75fcee7e91fcdad745a9d010a78c8 100644
--- a/tools/telemetry/telemetry/internal/util/find_dependencies.py
+++ b/tools/telemetry/telemetry/internal/util/find_dependencies.py
@@ -12,11 +12,12 @@ import sys
 import zipfile
 
 from telemetry import benchmark
-from telemetry.core import discover
 from telemetry.internal.util import bootstrap
 from telemetry.internal.util import command_line
 from telemetry.internal.util import path
 from telemetry.internal.util import path_set
+from telemetry.util import classes_util
+
 
 DEPS_FILE = 'bootstrap_deps'
 
@@ -61,10 +62,9 @@ def FindPageSetDependencies(base_dir):
 
   # Add base_dir to path so our imports relative to base_dir will work.
   sys.path.append(base_dir)
-  tests = discover.DiscoverClasses(base_dir, base_dir, benchmark.Benchmark,
-                                   index_by_class_name=True)
+  tests = classes_util.DiscoverClasses(base_dir, base_dir, benchmark.Benchmark)
 
-  for test_class in tests.itervalues():
+  for test_class in tests:
     test_obj = test_class()
 
     # Ensure the test's default options are set if needed.