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

Fortunately, all of the stories whosed names need to be trim down belong to
one off telemetry script (profile_generator) or Cluster Telemetry. Hence this
CL does not affect any benchmark's story name in production.

BUG=chromium:662941

Review-Url: https://codereview.chromium.org/2629413002
Cr-Commit-Position: refs/heads/master@{#443585}

tools/perf/page_sets/profile_safe_urls.py

@@ -11,6 +11,9 @@ 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')

tools/perf/page_sets/top_desktop_sites_2012Q3.py

@@ -251,7 +251,8 @@ class Top2012Q3Page(page.Page):
 
   def __init__(self, url, ps):
     super(Top2012Q3Page, self).__init__(
-        url=url, page_set=ps, credentials_path = 'data/credentials.json')
+        url=url, page_set=ps, credentials_path = 'data/credentials.json',
+        name=url[:140])  # Make sure page's name is not too long
     self.archive_data_file = 'data/2012Q3.json'
 
   def RunPageInteractions(self, action_runner):