Modify list_system_health_stories to generate_system_health_csv

tools/perf/page_sets/system_health/media_stories.py

Index: tools/perf/page_sets/system_health/media_stories.py
diff --git a/tools/perf/page_sets/system_health/media_stories.py b/tools/perf/page_sets/system_health/media_stories.py
index ad079e8d4b515282fcec217d1b9a326dc0bcc3a8..14edfac788e28ede2596c3050ed5b54149230201 100644
--- a/tools/perf/page_sets/system_health/media_stories.py
+++ b/tools/perf/page_sets/system_health/media_stories.py
@@ -58,6 +58,7 @@ class _MediaStory(system_health_story.SystemHealthStory):
 
 @benchmark.Disabled('all')  # crbug.com/649392
 class GooglePlayMusicDesktopStory(_MediaStory):
+  """Browse the songs list in music.google.com, then play a song."""
   NAME = 'play:media:google_play_music'
   URL = 'https://music.google.com'
 
@@ -83,6 +84,7 @@ class GooglePlayMusicDesktopStory(_MediaStory):
 
 @benchmark.Disabled('win')  # crbug.com/649392
 class SoundCloudDesktopStory(_MediaStory):
+  """Load soundcloud.com, search for "Smooth Jazz", then play a song."""
   NAME = 'play:media:soundcloud'
   URL = 'https://soundcloud.com'
 
@@ -101,6 +103,7 @@ class SoundCloudDesktopStory(_MediaStory):
 
 @decorators.Disabled('all')  # crbug.com/649392
 class PandoraDesktopStory(_MediaStory):
+  """Load pandora.com, then play a song."""
   NAME = 'play:media:pandora'
   URL = 'https://pandora.com'