[Chromecast] Fix playing audio stream events

Bug: internal b/156821522
Change-Id: I5f84f513eb299769800f98b8da313aad2ed26f61
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2230183
Commit-Queue: Kenneth MacKay <kmackay@chromium.org>
Commit-Queue: Yuchen Liu <yucliu@chromium.org>
Auto-Submit: Kenneth MacKay <kmackay@chromium.org>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#775214}

chromecast/media/cma/backend/media_pipeline_backend_manager.cc

@@ -134,9 +134,8 @@ void MediaPipelineBackendManager::UpdatePlayingAudioCount(
   DCHECK(change == -1 || change == 1) << "bad count change: " << change;
 
   bool had_playing_audio_streams = (TotalPlayingAudioStreamsCount() > 0);
-  // Volume feedback sounds are only allowed when there are no non-effects
-  // audio streams playing.
-  bool prev_allow_feedback = (TotalPlayingNoneffectsAudioStreamsCount() == 0);
+  bool had_playing_primary_streams =
+      (TotalPlayingNoneffectsAudioStreamsCount() > 0);
 
   playing_audio_streams_count_[type] += change;
   DCHECK_GE(playing_audio_streams_count_[type], 0);
@@ -147,7 +146,7 @@ void MediaPipelineBackendManager::UpdatePlayingAudioCount(
   }
 
   HandlePlayingAudioStreamsChange(had_playing_audio_streams,
-                                  prev_allow_feedback);
+                                  had_playing_primary_streams);
 }
 
 void MediaPipelineBackendManager::OnMixerStreamCountChange(int primary_streams,