[tools/perf] Trim down story name that has more than 180 charaters

tools/perf/page_sets/profile_safe_urls.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 profile_creators import profile_safe_url_list
 from telemetry.page import page as page_module
 from telemetry.page import shared_page_state
 from telemetry import story
 
 
 class ProfileSafeUrlPage(page_module.Page):
   def __init__(self, url, page_set):
     super(ProfileSafeUrlPage, self).__init__(
         url=url,
+        # Make sure story name is not too long and has type 'str' instead of
+        # 'unicode'.
+        name=str(url[:140]),
         page_set = page_set,
         shared_page_state_class=shared_page_state.SharedDesktopPageState,
         credentials_path = 'data/credentials.json')
     self.credentials = 'google'
 
 
 class ProfileSafeUrlsPageSet(story.StorySet):
   """Safe urls used for profile generation."""
 
   def __init__(self):
     super(ProfileSafeUrlsPageSet, self).__init__(
       archive_data_file='data/profile_safe_urls.json',
       cloud_storage_bucket=story.PARTNER_BUCKET)
 
     # Only use the first 500 urls to prevent the .wpr files from getting too
     # big.
     safe_urls = profile_safe_url_list.GetShuffledSafeUrls()[0:500]
     for safe_url in safe_urls:
       self.AddStory(ProfileSafeUrlPage(safe_url, self))