Propagate media play/pause to WebContentsObserver for Chromecast metrics

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 9fb8cacb4d6b54e30c79a99b5d674ff53ad2378e..bf77e42fb435bffe5b36ef9f76801feb5499fcd0 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -3326,12 +3326,16 @@ void WebContentsImpl::OnMediaPlayingNotification(int64 player_cookie,
     if (!video_power_save_blocker_ && !IsHidden())
       CreateVideoPowerSaveBlocker();
   }
+
+  FOR_EACH_OBSERVER(WebContentsObserver, observers_, MediaStartedPlaying());
 }
 
 void WebContentsImpl::OnMediaPausedNotification(int64 player_cookie) {
   RemoveMediaPlayerEntry(player_cookie, &active_audio_players_);
   RemoveMediaPlayerEntry(player_cookie, &active_video_players_);
   MaybeReleasePowerSaveBlockers();
+
+  FOR_EACH_OBSERVER(WebContentsObserver, observers_, MediaPaused());
 }
 
 void WebContentsImpl::OnFirstVisuallyNonEmptyPaint() {