Revert "assistant: add audio ducking for internal media"

This reverts commit f7860793.

Reason for revert: suspect causing compile failure on linux-chromeos-google-rel.

Sample build: https://ci.chromium.org/p/chrome/builders/ci/linux-chromeos-google-rel/8776

Original change's description:
> assistant: add audio ducking for internal media
> 
> Bug: b/135064564
> Test: locally build and run with multiple media playing
> Change-Id: I3814cfc3bc619077ca6781493fd369c27d50eb4e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1899184
> Commit-Queue: Xiaohui Chen <xiaohuic@chromium.org>
> Reviewed-by: Tao Wu <wutao@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#713200}

TBR=xiaohuic@chromium.org,wutao@chromium.org

Change-Id: I6595ecc2d3ea93a762996386f3af9bf297daed70
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: b/135064564
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1902180Reviewed-by: Takashi Sakamoto <tasak@google.com>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#713292}

chromeos/services/assistant/assistant_manager_service_impl.cc

@@ -1357,6 +1357,7 @@ void AssistantManagerServiceImpl::MediaSessionMetadataChanged(
   UpdateMediaState();
 }
 
+
 void AssistantManagerServiceImpl::OnPlaybackStateChange(
     const MediaStatus& status) {
   if (media_session_)

chromeos/services/assistant/media_session/assistant_media_session.cc

@@ -4,10 +4,7 @@
 
 #include "chromeos/services/assistant/media_session/assistant_media_session.h"
 
-#include <utility>
-
 #include "base/bind.h"
-#include "base/memory/scoped_refptr.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chromeos/services/assistant/assistant_manager_service_impl.h"
 #include "services/media_session/public/cpp/features.h"
@@ -28,10 +25,7 @@ const char kAudioFocusSourceName[] = "assistant";
 AssistantMediaSession::AssistantMediaSession(
     mojom::Client* client,
     AssistantManagerServiceImpl* assistant_manager)
-    : assistant_manager_service_(assistant_manager),
-      client_(client),
-      ducking_observers_(base::MakeRefCounted<
-                         base::ObserverListThreadSafe<DuckingObserver>>()) {}
+    : assistant_manager_service_(assistant_manager), client_(client) {}
 
 AssistantMediaSession::~AssistantMediaSession() {
   AbandonAudioFocusIfNeeded();
@@ -58,18 +52,20 @@ void AssistantMediaSession::GetDebugInfo(GetDebugInfoCallback callback) {
   std::move(callback).Run(std::move(info));
 }
 
+// TODO(b/135064564): Update StartDucking() and StopDucking() after volume
+// control API for media streams is implemented.
 void AssistantMediaSession::StartDucking() {
   if (is_ducking_)
     return;
   is_ducking_ = true;
-  NotifyDucking(FROM_HERE);
+  Suspend(SuspendType::kSystem);
 }
 
 void AssistantMediaSession::StopDucking() {
   if (!is_ducking_)
     return;
   is_ducking_ = false;
-  NotifyDucking(FROM_HERE);
+  Resume(SuspendType::kSystem);
 }
 
 void AssistantMediaSession::Suspend(SuspendType suspend_type) {
@@ -137,40 +133,6 @@ void AssistantMediaSession::AbandonAudioFocusIfNeeded() {
   internal_audio_focus_id_ = base::UnguessableToken::Null();
 }
 
-void AssistantMediaSession::NotifyMediaSessionMetadataChanged(
-    const assistant_client::MediaStatus& status) {
-  media_session::MediaMetadata metadata;
-
-  metadata.title = base::UTF8ToUTF16(status.metadata.title);
-  metadata.artist = base::UTF8ToUTF16(status.metadata.artist);
-  metadata.album = base::UTF8ToUTF16(status.metadata.album);
-
-  bool metadata_changed = metadata_ != metadata;
-  if (!metadata_changed)
-    return;
-
-  metadata_ = metadata;
-
-  current_track_ = status.track_type;
-
-  for (auto& observer : observers_)
-    observer->MediaSessionMetadataChanged(this->metadata_);
-}
-
-void AssistantMediaSession::AddDuckingObserver(DuckingObserver* observer) {
-  ducking_observers_->AddObserver(observer);
-  if (is_ducking_)
-    observer->SetDucking(is_ducking_);
-}
-
-void AssistantMediaSession::RemoveDuckingObserver(DuckingObserver* observer) {
-  ducking_observers_->RemoveObserver(observer);
-}
-
-base::WeakPtr<AssistantMediaSession> AssistantMediaSession::GetWeakPtr() {
-  return weak_factory_.GetWeakPtr();
-}
-
 void AssistantMediaSession::EnsureServiceConnection() {
   DCHECK(base::FeatureList::IsEnabled(
       media_session::features::kMediaSessionService));
@@ -212,6 +174,26 @@ void AssistantMediaSession::SetAudioFocusInfo(State audio_focus_state,
   NotifyMediaSessionInfoChanged();
 }
 
+void AssistantMediaSession::NotifyMediaSessionMetadataChanged(
+    const assistant_client::MediaStatus& status) {
+  media_session::MediaMetadata metadata;
+
+  metadata.title = base::UTF8ToUTF16(status.metadata.title);
+  metadata.artist = base::UTF8ToUTF16(status.metadata.artist);
+  metadata.album = base::UTF8ToUTF16(status.metadata.album);
+
+  bool metadata_changed = metadata_ != metadata;
+  if (!metadata_changed)
+    return;
+
+  metadata_ = metadata;
+
+  current_track_ = status.track_type;
+
+  for (auto& observer : observers_)
+    observer->MediaSessionMetadataChanged(this->metadata_);
+}
+
 media_session::mojom::MediaSessionInfoPtr
 AssistantMediaSession::GetMediaSessionInfoInternal() {
   media_session::mojom::MediaSessionInfoPtr info(
@@ -258,10 +240,8 @@ bool AssistantMediaSession::IsSuspended() const {
   return audio_focus_state_ == State::SUSPENDED;
 }
 
-void AssistantMediaSession::NotifyDucking(const base::Location& location) {
-  ducking_observers_->Notify(
-      location, &AssistantMediaSession::DuckingObserver::SetDucking,
-      is_ducking_);
+base::WeakPtr<AssistantMediaSession> AssistantMediaSession::GetWeakPtr() {
+  return weak_factory_.GetWeakPtr();
 }
 
 }  // namespace assistant

chromeos/services/assistant/media_session/assistant_media_session.h

@@ -6,8 +6,6 @@
 #define CHROMEOS_SERVICES_ASSISTANT_MEDIA_SESSION_ASSISTANT_MEDIA_SESSION_H_
 
 #include "base/macros.h"
-#include "base/memory/scoped_refptr.h"
-#include "base/observer_list_threadsafe.h"
 #include "base/timer/timer.h"
 #include "base/unguessable_token.h"
 #include "chromeos/services/assistant/public/mojom/assistant.mojom.h"
@@ -34,12 +32,6 @@ class AssistantMediaSession : public media_session::mojom::MediaSession {
  public:
   enum class State { ACTIVE, SUSPENDED, INACTIVE };
 
-  class DuckingObserver {
-   public:
-    virtual ~DuckingObserver() = default;
-    virtual void SetDucking(bool is_ducking) = 0;
-  };
-
   explicit AssistantMediaSession(
       mojom::Client* client,
       AssistantManagerServiceImpl* assistant_manager);
@@ -57,6 +49,8 @@ class AssistantMediaSession : public media_session::mojom::MediaSession {
       override;
   void PreviousTrack() override {}
   void NextTrack() override {}
+  void NotifyMediaSessionMetadataChanged(
+      const assistant_client::MediaStatus& status);
   void SkipAd() override {}
   void Seek(base::TimeDelta seek_time) override {}
   void Stop(SuspendType suspend_type) override {}
@@ -71,12 +65,6 @@ class AssistantMediaSession : public media_session::mojom::MediaSession {
   void RequestAudioFocus(media_session::mojom::AudioFocusType audio_focus_type);
   void AbandonAudioFocusIfNeeded();
 
-  void NotifyMediaSessionMetadataChanged(
-      const assistant_client::MediaStatus& status);
-
-  void AddDuckingObserver(DuckingObserver* observer);
-  void RemoveDuckingObserver(DuckingObserver* observer);
-
   base::WeakPtr<AssistantMediaSession> GetWeakPtr();
 
   // Returns internal audio focus id.
@@ -110,8 +98,6 @@ class AssistantMediaSession : public media_session::mojom::MediaSession {
   // Returns if the session is currently suspended.
   bool IsSuspended() const;
 
-  void NotifyDucking(const base::Location& from_here);
-
   // The current metadata associated with the current media session.
   media_session::MediaMetadata metadata_;
 
@@ -133,9 +119,6 @@ class AssistantMediaSession : public media_session::mojom::MediaSession {
   // StopDucking().
   bool is_ducking_ = false;
 
-  scoped_refptr<base::ObserverListThreadSafe<DuckingObserver>>
-      ducking_observers_;
-
   // If the media session has acquired audio focus then this will contain a
   // pointer to that requests AudioFocusRequestClient.
   mojo::Remote<media_session::mojom::AudioFocusRequestClient>

chromeos/services/assistant/platform/audio_device_owner.cc

@@ -7,7 +7,6 @@
 #include <algorithm>
 #include <utility>
 
-#include "chromeos/services/assistant/media_session/assistant_media_session.h"
 #include "media/audio/audio_device_description.h"
 #include "media/base/limits.h"
 #include "services/media_session/public/mojom/media_session.mojom.h"
@@ -71,17 +70,13 @@ media::AudioParameters GetAudioParametersFromBufferFormat(
 AudioDeviceOwner::AudioDeviceOwner(
     scoped_refptr<base::SequencedTaskRunner> task_runner,
     scoped_refptr<base::SequencedTaskRunner> background_task_runner,
-    const std::string& device_id,
-    AssistantMediaSession* media_session)
+    const std::string& device_id)
     : main_task_runner_(task_runner),
       background_task_runner_(background_task_runner),
-      device_id_(device_id),
-      media_session_(media_session) {}
+      device_id_(device_id) {}
 
 AudioDeviceOwner::~AudioDeviceOwner() {
   DCHECK(background_task_runner_->RunsTasksInCurrentSequence());
-  if (output_device_)
-    media_session_->RemoveDuckingObserver(this);
 }
 
 void AudioDeviceOwner::StartOnMainThread(
@@ -126,34 +121,20 @@ void AudioDeviceOwner::StartOnMainThread(
 
 void AudioDeviceOwner::StopOnBackgroundThread() {
   DCHECK(background_task_runner_->RunsTasksInCurrentSequence());
-  media_session_->RemoveDuckingObserver(this);
+  base::AutoLock lock(lock_);
   output_device_.reset();
-  {
-    base::AutoLock lock(lock_);
-    if (delegate_) {
-      delegate_->OnStopped();
-      delegate_ = nullptr;
-    }
+  if (delegate_) {
+    delegate_->OnStopped();
+    delegate_ = nullptr;
   }
 }
 
-void AudioDeviceOwner::SetDucking(bool is_ducking) {
-  // |output_device_| is only accessed on background thread.
-  DCHECK(background_task_runner_->RunsTasksInCurrentSequence());
-
-  constexpr double kDuckingVolume = 0.2;
-  if (output_device_)
-    output_device_->SetVolume(is_ducking ? kDuckingVolume : 1.0);
-}
-
 void AudioDeviceOwner::StartDeviceOnBackgroundThread(
     mojo::PendingRemote<audio::mojom::StreamFactory> stream_factory) {
   DCHECK(background_task_runner_->RunsTasksInCurrentSequence());
   output_device_ = std::make_unique<audio::OutputDevice>(
       std::move(stream_factory), audio_param_, this, device_id_);
   output_device_->Play();
-
-  media_session_->AddDuckingObserver(this);
 }
 
 int AudioDeviceOwner::Render(base::TimeDelta delay,

chromeos/services/assistant/platform/audio_device_owner.h

@@ -11,7 +11,6 @@
 
 #include "base/component_export.h"
 #include "base/macros.h"
-#include "chromeos/services/assistant/media_session/assistant_media_session.h"
 #include "libassistant/shared/public/platform_audio_output.h"
 #include "media/base/audio_block_fifo.h"
 #include "media/base/audio_parameters.h"
@@ -24,14 +23,12 @@ namespace chromeos {
 namespace assistant {
 
 class COMPONENT_EXPORT(ASSISTANT_SERVICE) AudioDeviceOwner
-    : public media::AudioRendererSink::RenderCallback,
-      AssistantMediaSession::DuckingObserver {
+    : public media::AudioRendererSink::RenderCallback {
  public:
   AudioDeviceOwner(
       scoped_refptr<base::SequencedTaskRunner> task_runner,
       scoped_refptr<base::SequencedTaskRunner> background_task_runner,
-      const std::string& device_id,
-      AssistantMediaSession* media_session);
+      const std::string& device_id);
   ~AudioDeviceOwner() override;
 
   void StartOnMainThread(
@@ -41,9 +38,6 @@ class COMPONENT_EXPORT(ASSISTANT_SERVICE) AudioDeviceOwner
 
   void StopOnBackgroundThread();
 
-  // AssistantMediaSession::DuckingObserver overrides:
-  void SetDucking(bool is_ducking) override;
-
   // media::AudioRenderSink::RenderCallback overrides:
   int Render(base::TimeDelta delay,
              base::TimeTicks delay_timestamp,
@@ -84,8 +78,6 @@ class COMPONENT_EXPORT(ASSISTANT_SERVICE) AudioDeviceOwner
   assistant_client::OutputStreamFormat format_;
   media::AudioParameters audio_param_;
 
-  AssistantMediaSession* media_session_;
-
   DISALLOW_COPY_AND_ASSIGN(AudioDeviceOwner);
 };
 

chromeos/services/assistant/platform/audio_output_provider_impl.cc

@@ -48,8 +48,7 @@ class AudioOutputImpl : public assistant_client::AudioOutput {
             std::make_unique<AudioStreamHandler>(task_runner)),
         device_owner_(std::make_unique<AudioDeviceOwner>(task_runner,
                                                          background_task_runner,
-                                                         device_id,
-                                                         media_session)) {}
+                                                         device_id)) {}
 
   ~AudioOutputImpl() override {
     // This ensures that it will be executed after StartOnMainThread.