Explicitly set a story name for DummyPage

tools/perf/page_sets/dummy_story_set.py

 # Copyright 2015 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 as page_module
 from telemetry import story
 
 
 class DummyPage(page_module.Page):
 
   def __init__(self, page_set):
     super(DummyPage, self).__init__(
       url='file://dummy_pages/dummy_page.html',
+      name='dummy_page.html',
       page_set=page_set)
 
   def RunPageInteractions(self, action_runner):
     assert action_runner.EvaluateJavaScript('1 + window.__dummy_value') == 2
 
 
 class BrokenDummyPage(page_module.Page):
 
   def __init__(self, page_set):
     super(BrokenDummyPage, self).__init__(
       url='file://dummy_pages/dummy_page.html',
       name='Broken dummy page',
       page_set=page_set)
 
   def RunPageInteractions(self, action_runner):
     # The call below should raise an AssertionError
     assert action_runner.EvaluateJavaScript('1 + window.__dummy_value') == 3
 
 
 class DummyStorySet(story.StorySet):
 
   def __init__(self):
-    super(DummyStorySet, self).__init__()
+    super(DummyStorySet, self).__init__(verify_names=True)
     self.AddStory(DummyPage(self))