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diff --git a/dom/media/mediasink/AudioSinkWrapper.h b/dom/media/mediasink/AudioSinkWrapper.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef AudioSinkWrapper_h_
+#define AudioSinkWrapper_h_
+
+#include "mozilla/AbstractThread.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/UniquePtr.h"
+
+#include "AudioSink.h"
+#include "MediaSink.h"
+
+namespace mozilla {
+class MediaData;
+template <class T>
+class MediaQueue;
+
+/**
+ * A wrapper around AudioSink to provide the interface of MediaSink.
+ */
+class AudioSinkWrapper : public MediaSink {
+  using PlaybackParams = AudioSink::PlaybackParams;
+
+  // An AudioSink factory.
+  class Creator {
+   public:
+    virtual ~Creator() = default;
+    virtual AudioSink* Create() = 0;
+  };
+
+  // Wrap around a function object which creates AudioSinks.
+  template <typename Function>
+  class CreatorImpl : public Creator {
+   public:
+    explicit CreatorImpl(const Function& aFunc) : mFunction(aFunc) {}
+    AudioSink* Create() override { return mFunction(); }
+
+   private:
+    Function mFunction;
+  };
+
+ public:
+  template <typename Function>
+  AudioSinkWrapper(AbstractThread* aOwnerThread,
+                   MediaQueue<AudioData>& aAudioQueue, const Function& aFunc,
+                   double aVolume, double aPlaybackRate, bool aPreservesPitch,
+                   RefPtr<AudioDeviceInfo> aAudioDevice)
+      : mOwnerThread(aOwnerThread),
+        mCreator(new CreatorImpl<Function>(aFunc)),
+        mAudioDevice(std::move(aAudioDevice)),
+        mIsStarted(false),
+        mParams(aVolume, aPlaybackRate, aPreservesPitch),
+        // Give an invalid value to facilitate debug if used before playback
+        // starts.
+        mPlayDuration(media::TimeUnit::Invalid()),
+        mAudioEnded(true),
+        mAudioQueue(aAudioQueue) {}
+
+  RefPtr<EndedPromise> OnEnded(TrackType aType) override;
+  media::TimeUnit GetEndTime(TrackType aType) const override;
+  media::TimeUnit GetPosition(TimeStamp* aTimeStamp = nullptr) override;
+  bool HasUnplayedFrames(TrackType aType) const override;
+  media::TimeUnit UnplayedDuration(TrackType aType) const override;
+  void DropAudioPacketsIfNeeded(const media::TimeUnit& aMediaPosition);
+
+  void SetVolume(double aVolume) override;
+  void SetStreamName(const nsAString& aStreamName) override;
+  void SetPlaybackRate(double aPlaybackRate) override;
+  void SetPreservesPitch(bool aPreservesPitch) override;
+  void SetPlaying(bool aPlaying) override;
+
+  double PlaybackRate() const override;
+
+  nsresult Start(const media::TimeUnit& aStartTime,
+                 const MediaInfo& aInfo) override;
+  void Stop() override;
+  bool IsStarted() const override;
+  bool IsPlaying() const override;
+
+  const AudioDeviceInfo* AudioDevice() const override { return mAudioDevice; }
+
+  void Shutdown() override;
+
+  void GetDebugInfo(dom::MediaSinkDebugInfo& aInfo) override;
+
+  void EnableTreatAudioUnderrunAsSilence(bool aEnabled) override;
+
+ private:
+  // The clock that was in use for the previous position query, allowing to
+  // detect clock switches.
+  enum class ClockSource {
+    // The clock comes from an underlying system-level audio stream.
+    AudioStream,
+    // The clock comes from the system clock.
+    SystemClock,
+    // The stream is paused, a constant time is reported.
+    Paused
+  } mLastClockSource = ClockSource::Paused;
+  bool IsMuted() const;
+  void OnMuted(bool aMuted);
+  virtual ~AudioSinkWrapper();
+
+  void AssertOwnerThread() const {
+    MOZ_ASSERT(mOwnerThread->IsCurrentThreadIn());
+  }
+
+  // An AudioSink can be started synchronously from the MDSM thread, or
+  // asynchronously.
+  // In synchronous mode, the clock doesn't advance until the sink has been
+  // created, initialized and started. This is useful for the initial startup,
+  // and when seeking.
+  // In asynchronous mode, the clock will keep going forward (using the system
+  // clock) until the AudioSink is started, at which point the clock will use
+  // the AudioSink clock. This is used when unmuting a media element.
+  enum class AudioSinkStartPolicy { SYNC, ASYNC };
+  nsresult StartAudioSink(const media::TimeUnit& aStartTime,
+                          AudioSinkStartPolicy aPolicy);
+
+  // Get the current media position using the system clock. This is used when
+  // the audio is muted, or when the media has no audio track. Otherwise, the
+  // media's position is based on the clock of the AudioStream.
+  media::TimeUnit GetSystemClockPosition(TimeStamp aNow) const;
+  bool CheckIfEnded() const;
+
+  void OnAudioEnded();
+
+  bool IsAudioSourceEnded(const MediaInfo& aInfo) const;
+
+  const RefPtr<AbstractThread> mOwnerThread;
+  UniquePtr<Creator> mCreator;
+  UniquePtr<AudioSink> mAudioSink;
+  // The output device this AudioSink is playing data to. The system's default
+  // device is used if this is null.
+  const RefPtr<AudioDeviceInfo> mAudioDevice;
+  // Will only exist when media has an audio track.
+  RefPtr<EndedPromise> mEndedPromise;
+  MozPromiseHolder<EndedPromise> mEndedPromiseHolder;
+
+  bool mIsStarted;
+  PlaybackParams mParams;
+
+  TimeStamp mPlayStartTime;
+  media::TimeUnit mPlayDuration;
+
+  bool mAudioEnded;
+  MozPromiseRequestHolder<EndedPromise> mAudioSinkEndedPromise;
+  MediaQueue<AudioData>& mAudioQueue;
+
+  // True if we'd like to treat underrun as silent frames. But that can only be
+  // applied in the special situation for seamless looping.
+  bool mTreatUnderrunAsSilence = false;
+};
+
+}  // namespace mozilla
+
+#endif  // AudioSinkWrapper_h_