Introduce PageCyclerStory and let the stories wait for onload+TTI

tools/perf/page_sets/page_cycler_story.py

+# Copyright 2016 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 import page
+from telemetry.page import cache_temperature as cache_temperature_module
+from telemetry.page import shared_page_state
+
+_TTI_WAIT_TIME = 10
+
+class PageCyclerStory(page.Page):
+
+  def __init__(self, url, page_set,
+      shared_page_state_class=shared_page_state.SharedDesktopPageState,
+      cache_temperature=cache_temperature_module.ANY, **kwargs):
+    super(PageCyclerStory, self).__init__(
+        url=url, page_set=page_set,
+        shared_page_state_class=shared_page_state_class,
+        cache_temperature=cache_temperature,
+        **kwargs)
+
+  def RunPageInteractions(self, action_runner):
+    action_runner.tab.WaitForDocumentReadyStateToBeComplete()
+    action_runner.Wait(_TTI_WAIT_TIME)