Do not play the whole media file before seeking.

tools/perf/page_sets/tough_video_cases.py

 # Copyright 2014 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
 
 _PAGE_TAGS_LIST = [
     # Audio codecs:
     'pcm',
     'mp3',
@@ skipping 27 matching lines @@
 
   def LoopMixedAudio(self, action_runner):
     action_runner.PlayMedia(selector='#background_audio',
                             playing_event_timeout_in_seconds=60)
     action_runner.LoopMedia(loop_count=50, selector='#mixed_audio')
 
   def LoopSingleAudio(self, action_runner):
     action_runner.LoopMedia(loop_count=50, selector='#single_audio')
 
   def PlayAction(self, action_runner):
+    # Play the media until it has finished or it times out.
     action_runner.PlayMedia(playing_event_timeout_in_seconds=60,
                             ended_event_timeout_in_seconds=60)
 
   def SeekBeforeAndAfterPlayhead(self, action_runner,
                                  action_timeout_in_seconds=60):
     timeout = action_timeout_in_seconds
-    # Because an ended timeout is passed, this won't return until the media has
-    # played through.
-    action_runner.PlayMedia(playing_event_timeout_in_seconds=timeout,
-                            ended_event_timeout_in_seconds=timeout)
-    # Wait 1 second for no reason in particular.
+    # Start the media playback.
+    action_runner.PlayMedia(
+        playing_event_timeout_in_seconds=timeout)
+    # Wait for 1 second so that we know the play-head is at ~1s.
     action_runner.Wait(1)
     # Seek to before the play-head location.
     action_runner.SeekMedia(seconds=0.5, timeout_in_seconds=timeout,
                             label='seek_warm')
     # Seek to after the play-head location.
     action_runner.SeekMedia(seconds=9, timeout_in_seconds=timeout,
                             label='seek_cold')
 
 
 class Page1(ToughVideoCasesPage):
@@ skipping 500 matching lines @@
     self.add_browser_metrics = True
 
   def RunPageInteractions(self, action_runner):
     self.SeekBeforeAndAfterPlayhead(action_runner,
                                     action_timeout_in_seconds=120)
 
 class Page37(ToughVideoCasesPage):
 
   def __init__(self, page_set):
     super(Page37, self).__init__(
-      url='file://tough_video_cases/video.html?src=crowd1080_vp9.webm&canvas=true',
+      url=('file://tough_video_cases/video.html?src=crowd1080_vp9.webm&canvas='
+           'true'),
       page_set=page_set,
       tags=['vp9', 'video_only'])
 
     self.add_browser_metrics = True
 
   def RunPageInteractions(self, action_runner):
     self.PlayAction(action_runner)
 
 class Page38(ToughVideoCasesPage):
 
   def __init__(self, page_set):
     super(Page38, self).__init__(
       url='file://tough_video_cases/video.html?src=tulip2.mp4&canvas=true',
       page_set=page_set,
       tags=['h264', 'aac', 'audio_video'])
 
     self.add_browser_metrics = True
 
   def RunPageInteractions(self, action_runner):
     self.SeekBeforeAndAfterPlayhead(action_runner)
 
 class Page39(ToughVideoCasesPage):
 
   def __init__(self, page_set):
     super(Page39, self).__init__(
-      url='file://tough_video_cases/video.html?src=garden2_10s.webm&canvas=true',
+      url=('file://tough_video_cases/video.html?src=garden2_10s.webm&canvas='
+           'true'),
       page_set=page_set,
       tags=['is_4k', 'vp8', 'vorbis', 'audio_video'])
 
     self.add_browser_metrics = True
 
   def RunPageInteractions(self, action_runner):
     self.PlayAction(action_runner)
 
 class Page40(ToughVideoCasesPage):
 
@@ skipping 11 matching lines @@
   def RunPageInteractions(self, action_runner):
     self.PlayAction(action_runner)
 
 class ToughVideoCasesPageSet(story.StorySet):
   """
   Description: Video Stack Perf benchmark that report time_to_play.
   """
   def __init__(self):
     super(ToughVideoCasesPageSet, self).__init__(
             cloud_storage_bucket=story.PARTNER_BUCKET)
+    # TODO(crouleau): Pages 36 and 38 are in ToughVideoCasesPageSet even though
+    # they both report seek time instead of time_to_play.
+    # This may be a non-issue because we plan to merge these two page sets back
+    # together and use tags to allow teams to filter which pages they want.
 
     self.AddStory(Page1(self))
     self.AddStory(Page2(self))
     self.AddStory(Page3(self))
     self.AddStory(Page4(self))
     self.AddStory(Page5(self))
     self.AddStory(Page6(self))
     self.AddStory(Page7(self))
     self.AddStory(Page8(self))
     self.AddStory(Page9(self))
@@ skipping 11 matching lines @@
     self.AddStory(Page34(self))
     self.AddStory(Page36(self))
     self.AddStory(Page37(self))
     self.AddStory(Page38(self))
     self.AddStory(Page39(self))
     self.AddStory(Page40(self))
 
 
 class ToughVideoCasesExtraPageSet(story.StorySet):
   """
-  Description: Video Stack Perf benchmark that don't report time_to_play.
+  Description: Video Stack Perf benchmarks that report seek time and audio
+  avg_loop_time.
   """
   def __init__(self):
     super(ToughVideoCasesExtraPageSet, self).__init__(
             cloud_storage_bucket=story.PARTNER_BUCKET)
 
     self.AddStory(Page19(self))
     self.AddStory(Page20(self))
     self.AddStory(Page21(self))
     self.AddStory(Page22(self))
     self.AddStory(Page23(self))
     self.AddStory(Page24(self))
     self.AddStory(Page25(self))
     self.AddStory(Page26(self))
     self.AddStory(Page27(self))
     self.AddStory(Page28(self))
     self.AddStory(Page29(self))
     self.AddStory(Page31(self))
     self.AddStory(Page33(self))
     self.AddStory(Page35(self))