Remove Media.Pepper.PlayedSound histogram.

Fixed: 1167843
Change-Id: Ic4f3a5bcd88ea036a6ec82ddc91d0946622c7968
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2639654Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845394}

content/browser/media/session/pepper_playback_observer.cc

@@ -55,7 +55,6 @@ void PepperPlaybackObserver::PepperInstanceDeleted(
   if (iter == players_played_sound_map_.end())
     return;
 
-  UMA_HISTOGRAM_BOOLEAN("Media.Pepper.PlayedSound", iter->second);
   players_played_sound_map_.erase(iter);
 
   PepperStopsPlayback(render_frame_host, pp_instance);

tools/metrics/histograms/histograms_xml/media/histograms.xml

@@ -2861,6 +2861,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Media.Pepper.PlayedSound" enum="Boolean"
     expires_after="2021-03-01">
+  <obsolete>
+    Deprecated as of 2021/01.
+  </obsolete>
   <owner>mlamouri@google.com</owner>
   <owner>media-dev@chromium.org</owner>
   <summary>