[Chromecast] Add an interface for MediaPipelineBackendManager to set

global volume multiplier for extra audio streams.

Bug: b/134381697
Test: On device
Change-Id: Idbabbfef0381f00d330263d721c6da0fc4c752ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1681384
Commit-Queue: Junbo Ke <juke@chromium.org>
Reviewed-by: Kenneth MacKay <kmackay@chromium.org>
Cr-Commit-Position: refs/heads/master@{#673399}

chromecast/media/cma/backend/BUILD.gn

@@ -24,6 +24,7 @@ cast_source_set("backend") {
     "cma_backend_factory.h",
     "cma_backend_factory_impl.cc",
     "cma_backend_factory_impl.h",
+    "extra_audio_stream.h",
     "media_pipeline_backend_manager.cc",
     "media_pipeline_backend_manager.h",
     "media_pipeline_backend_wrapper.cc",

chromecast/media/cma/backend/extra_audio_stream.h

+// Copyright 2019 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.
+
+#ifndef CHROMECAST_MEDIA_CMA_BACKEND_EXTRA_AUDIO_STREAM_H_
+#define CHROMECAST_MEDIA_CMA_BACKEND_EXTRA_AUDIO_STREAM_H_
+
+namespace chromecast {
+namespace media {
+
+class ExtraAudioStream {
+ public:
+  virtual void SetGlobalVolumeMultiplier(float multiplier) = 0;
+
+ protected:
+  virtual ~ExtraAudioStream() = default;
+};
+
+}  // namespace media
+}  // namespace chromecast
+
+#endif  // CHROMECAST_MEDIA_CMA_BACKEND_EXTRA_AUDIO_STREAM_H_

chromecast/media/cma/backend/media_pipeline_backend_manager.cc

@@ -15,6 +15,7 @@
 #include "chromecast/chromecast_buildflags.h"
 #include "chromecast/media/cma/backend/audio_decoder_wrapper.h"
 #include "chromecast/media/cma/backend/cma_backend.h"
+#include "chromecast/media/cma/backend/extra_audio_stream.h"
 #include "chromecast/media/cma/backend/media_pipeline_backend_wrapper.h"
 #include "chromecast/public/volume_control.h"
 
@@ -209,16 +210,23 @@ void MediaPipelineBackendManager::RemoveAllowVolumeFeedbackObserver(
 
 void MediaPipelineBackendManager::AddExtraPlayingStream(
     bool sfx,
-    const AudioContentType type) {
-  MAKE_SURE_MEDIA_THREAD(AddExtraPlayingStream, sfx, type);
+    const AudioContentType type,
+    ExtraAudioStream* extra_audio_stream) {
+  MAKE_SURE_MEDIA_THREAD(AddExtraPlayingStream, sfx, type, extra_audio_stream);
   UpdatePlayingAudioCount(sfx, type, 1);
+  if (extra_audio_stream)
+    extra_audio_streams_[type].emplace(extra_audio_stream);
 }
 
 void MediaPipelineBackendManager::RemoveExtraPlayingStream(
     bool sfx,
-    const AudioContentType type) {
-  MAKE_SURE_MEDIA_THREAD(RemoveExtraPlayingStream, sfx, type);
+    const AudioContentType type,
+    ExtraAudioStream* extra_audio_stream) {
+  MAKE_SURE_MEDIA_THREAD(RemoveExtraPlayingStream, sfx, type,
+                         extra_audio_stream);
   UpdatePlayingAudioCount(sfx, type, -1);
+  if (extra_audio_stream)
+    extra_audio_streams_[type].erase(extra_audio_stream);
 }
 
 void MediaPipelineBackendManager::SetGlobalVolumeMultiplier(
@@ -232,6 +240,9 @@ void MediaPipelineBackendManager::SetGlobalVolumeMultiplier(
       a->SetGlobalVolumeMultiplier(multiplier);
     }
   }
+  for (auto* extra_audio_stream : extra_audio_streams_[type]) {
+    extra_audio_stream->SetGlobalVolumeMultiplier(multiplier);
+  }
 }
 
 void MediaPipelineBackendManager::SetBufferDelegate(

chromecast/media/cma/backend/media_pipeline_backend_manager.h

@@ -26,6 +26,7 @@ namespace media {
 enum class AudioContentType;
 class CastDecoderBuffer;
 class CmaBackend;
+class ExtraAudioStream;
 class MediaPipelineBackendWrapper;
 class ActiveAudioDecoderWrapper;
 class ActiveMediaPipelineBackendWrapper;
@@ -115,8 +116,12 @@ class MediaPipelineBackendManager {
   // CmaBackend instance (for example, direct audio output using
   // CastMediaShlib::AddDirectAudioSource()). |sfx| indicates whether or not
   // the stream is a sound effects stream (has no effect on volume feedback).
-  void AddExtraPlayingStream(bool sfx, const AudioContentType type);
-  void RemoveExtraPlayingStream(bool sfx, const AudioContentType type);
+  void AddExtraPlayingStream(bool sfx,
+                             const AudioContentType type,
+                             ExtraAudioStream* extra_audio_stream = nullptr);
+  void RemoveExtraPlayingStream(bool sfx,
+                                const AudioContentType type,
+                                ExtraAudioStream* extra_audio_stream = nullptr);
 
   // Sets a global multiplier for output volume for streams of the given |type|.
   // The multiplier may be any value >= 0; if the resulting volume for an
@@ -173,6 +178,8 @@ class MediaPipelineBackendManager {
       allow_volume_feedback_observers_;
 
   base::flat_set<ActiveAudioDecoderWrapper*> audio_decoders_;
+  base::flat_map<AudioContentType, base::flat_set<ExtraAudioStream*>>
+      extra_audio_streams_;
   base::flat_map<AudioContentType, float> global_volume_multipliers_;
 
   // Previously issued MediaPipelineBackendWrapper that uses a video decoder.