[telemetry] Prototype for specifying page sets using Python imports and Telemetry discovery.

tools/perf/page_sets/__init__.py

Index: tools/perf/page_sets/__init__.py
diff --git a/tools/perf/page_sets/__init__.py b/tools/perf/page_sets/__init__.py
index 96196cffb2720d69ac46a41dd9bb9f4005bcfa9e..36a23b43274917573f2ba939d7e0eeffdddd5422 100644
--- a/tools/perf/page_sets/__init__.py
+++ b/tools/perf/page_sets/__init__.py
@@ -1,3 +1,19 @@
-# Copyright (c) 2012 The Chromium Authors. All rights reserved.
+# 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 inspect
+import os
+import sys
+
+from telemetry.core import discover
+from telemetry.page import page_set
+
+
+# Import all submodules' PageSet classes.
+start_dir = os.path.dirname(os.path.abspath(__file__))
+top_level_dir = os.path.dirname(start_dir)
+base_class = page_set.PageSet
+for cls in discover.DiscoverClasses(
+    start_dir, top_level_dir, base_class).values():
+  setattr(sys.modules[__name__], cls.__name__, cls)