[Chromecast] Rename AllowVolumeFeedbackObserver to ActiveAudioStreamObserver

So the name better matches the actual use.

Merge-With: eureka-internal/360190

Bug: none
Change-Id: Icad7d7496a67e6af96f72ccc73e41e0c2d68d935
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2039295Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Commit-Queue: Kenneth MacKay <kmackay@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738681}

chromecast/media/cma/backend/media_pipeline_backend_manager.cc

@@ -54,8 +54,9 @@ MediaPipelineBackendManager::MediaPipelineBackendManager(
            {AudioContentType::kAlarm, 0},
            {AudioContentType::kCommunication, 0},
            {AudioContentType::kOther, 0}}),
-      allow_volume_feedback_observers_(
-          new base::ObserverListThreadSafe<AllowVolumeFeedbackObserver>()),
+      active_audio_stream_observers_(
+          base::MakeRefCounted<
+              base::ObserverListThreadSafe<ActiveAudioStreamObserver>>()),
       backend_wrapper_using_video_decoder_(nullptr),
       buffer_delegate_(nullptr),
       weak_factory_(this) {
@@ -153,18 +154,19 @@ void MediaPipelineBackendManager::OnMixerStreamCountChange(int primary_streams,
                                                            int sfx_streams) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   bool had_playing_audio_streams = (TotalPlayingAudioStreamsCount() > 0);
-  bool prev_allow_feedback = (TotalPlayingNoneffectsAudioStreamsCount() == 0);
+  bool had_playing_primary_streams =
+      (TotalPlayingNoneffectsAudioStreamsCount() > 0);
 
   mixer_primary_stream_count_ = primary_streams;
   mixer_sfx_stream_count_ = sfx_streams;
 
   HandlePlayingAudioStreamsChange(had_playing_audio_streams,
-                                  prev_allow_feedback);
+                                  had_playing_primary_streams);
 }
 
 void MediaPipelineBackendManager::HandlePlayingAudioStreamsChange(
     bool had_playing_audio_streams,
-    bool prev_allow_feedback) {
+    bool had_playing_primary_streams) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   int new_playing_audio_streams = TotalPlayingAudioStreamsCount();
   if (new_playing_audio_streams == 0) {
@@ -179,11 +181,12 @@ void MediaPipelineBackendManager::HandlePlayingAudioStreamsChange(
     }
   }
 
-  bool new_allow_feedback = (TotalPlayingNoneffectsAudioStreamsCount() == 0);
-  if (new_allow_feedback != prev_allow_feedback) {
-    allow_volume_feedback_observers_->Notify(
-        FROM_HERE, &AllowVolumeFeedbackObserver::AllowVolumeFeedbackSounds,
-        new_allow_feedback);
+  bool new_playing_primary_streams =
+      (TotalPlayingNoneffectsAudioStreamsCount() > 0);
+  if (new_playing_primary_streams != had_playing_primary_streams) {
+    active_audio_stream_observers_->Notify(
+        FROM_HERE, &ActiveAudioStreamObserver::OnActiveAudioStreamChange,
+        new_playing_primary_streams);
   }
 }
 
@@ -213,14 +216,14 @@ void MediaPipelineBackendManager::EnterPowerSaveMode() {
   VolumeControl::SetPowerSaveMode(true);
 }
 
-void MediaPipelineBackendManager::AddAllowVolumeFeedbackObserver(
-    AllowVolumeFeedbackObserver* observer) {
-  allow_volume_feedback_observers_->AddObserver(observer);
+void MediaPipelineBackendManager::AddActiveAudioStreamObserver(
+    ActiveAudioStreamObserver* observer) {
+  active_audio_stream_observers_->AddObserver(observer);
 }
 
-void MediaPipelineBackendManager::RemoveAllowVolumeFeedbackObserver(
-    AllowVolumeFeedbackObserver* observer) {
-  allow_volume_feedback_observers_->RemoveObserver(observer);
+void MediaPipelineBackendManager::RemoveActiveAudioStreamObserver(
+    ActiveAudioStreamObserver* observer) {
+  active_audio_stream_observers_->RemoveObserver(observer);
 }
 
 void MediaPipelineBackendManager::AddExtraPlayingStream(

chromecast/media/cma/backend/media_pipeline_backend_manager.h

@@ -36,12 +36,15 @@ class MediaResourceTracker;
 // streams (apart from sound-effects streams).
 class MediaPipelineBackendManager {
  public:
-  class AllowVolumeFeedbackObserver {
+  class ActiveAudioStreamObserver {
    public:
-    virtual void AllowVolumeFeedbackSounds(bool allow) = 0;
+    // Called when we transition between "no active audio streams" and
+    // "have at least one active audio stream" states. For this purpose, sound
+    // effects streams are ignored.
+    virtual void OnActiveAudioStreamChange(bool have_active_streams) = 0;
 
    protected:
-    virtual ~AllowVolumeFeedbackObserver() = default;
+    virtual ~ActiveAudioStreamObserver() = default;
   };
 
   // Delegate which can process Audio buffers sent to us.
@@ -109,8 +112,8 @@ class MediaPipelineBackendManager {
 
   // Adds/removes an observer for when volume feedback sounds are allowed.
   // An observer must be removed on the same thread that added it.
-  void AddAllowVolumeFeedbackObserver(AllowVolumeFeedbackObserver* observer);
-  void RemoveAllowVolumeFeedbackObserver(AllowVolumeFeedbackObserver* observer);
+  void AddActiveAudioStreamObserver(ActiveAudioStreamObserver* observer);
+  void RemoveActiveAudioStreamObserver(ActiveAudioStreamObserver* observer);
 
   // Add/remove a playing audio stream that is not accounted for by a
   // CmaBackend instance. |sfx| indicates whether or not the stream is a sound
@@ -150,7 +153,7 @@ class MediaPipelineBackendManager {
                                int change);
   void OnMixerStreamCountChange(int primary_streams, int sfx_streams);
   void HandlePlayingAudioStreamsChange(bool had_playing_audio_streams,
-                                       bool prev_allow_feedback);
+                                       bool had_playing_primary_streams);
   int TotalPlayingAudioStreamsCount();
   int TotalPlayingNoneffectsAudioStreamsCount();
 
@@ -168,8 +171,8 @@ class MediaPipelineBackendManager {
   // Total number of playing non-effects streams.
   base::flat_map<AudioContentType, int> playing_noneffects_audio_streams_count_;
 
-  scoped_refptr<base::ObserverListThreadSafe<AllowVolumeFeedbackObserver>>
-      allow_volume_feedback_observers_;
+  scoped_refptr<base::ObserverListThreadSafe<ActiveAudioStreamObserver>>
+      active_audio_stream_observers_;
 
   // Previously issued MediaPipelineBackendWrapper that uses a video decoder.
   MediaPipelineBackendWrapper* backend_wrapper_using_video_decoder_;