Add support for python pageset

tools/telemetry/unittest_data/test_page_set.py

+# Copyright (c) 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.
+
+from telemetry.page.page_set import PageSet
+from telemetry.page.page import Page
+
+class TestPageSet(PageSet):
+  def __init__(self):
+    super(TestPageSet, self).__init__(
+      description='A pageset for testing purpose',
+      archive_data_file='data/test.json',
+      credentials_path='data/credential',
+      user_agent_type='desktop')
+
+    #top google property; a google tab is often open
+    class Google(Page):
+      def __init__(self):
+        super(Google, self).__init__('https://www.google.com')
+
+      def RunGetActionRunner(self, action_runner):
+        return action_runner
+
+    self.AddPage(Google())
+