diff --git a/dom/media/MediaDecoderStateMachine.cpp b/dom/media/MediaDecoderStateMachine.cpp
index 25d5208e6d5..2a72c58baf4 100644
--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -412,7 +412,7 @@ bool MediaDecoderStateMachine::HasFutureAudio()
   //    we've completely decoded all audio (but not finished playing it yet
   //    as per 1).
   return !mAudioCompleted &&
-         (AudioDecodedUsecs() >
+         (GetDecodedAudioDuration() >
             mLowAudioThresholdUsecs * mPlaybackRate ||
           AudioQueue().IsFinished());
 }
@@ -1817,18 +1817,6 @@ MediaDecoderStateMachine::StartMediaSink()
   }
 }
 
-int64_t MediaDecoderStateMachine::AudioDecodedUsecs()
-{
-  MOZ_ASSERT(OnTaskQueue());
-  NS_ASSERTION(HasAudio(),
-               "Should only call AudioDecodedUsecs() when we have audio");
-  // The amount of audio we have decoded is the amount of audio data we've
-  // already decoded and pushed to the hardware, plus the amount of audio
-  // data waiting to be pushed to the hardware.
-  int64_t pushed = mMediaSink->IsStarted() ? (AudioEndTime() - GetMediaTime()) : 0;
-  return pushed + AudioQueue().Duration();
-}
-
 bool MediaDecoderStateMachine::HasLowDecodedData(int64_t aAudioUsecs)
 {
   MOZ_ASSERT(OnTaskQueue());
@@ -1837,7 +1825,7 @@ bool MediaDecoderStateMachine::HasLowDecodedData(int64_t aAudioUsecs)
   // provided we've not decoded to the end of the audio stream, or
   // if we're low on video frames, provided
   // we've not decoded to the end of the video stream.
-  return ((IsAudioDecoding() && AudioDecodedUsecs() < aAudioUsecs) ||
+  return ((IsAudioDecoding() && GetDecodedAudioDuration() < aAudioUsecs) ||
          (IsVideoDecoding() &&
           static_cast<uint32_t>(VideoQueue().GetSize()) < LOW_VIDEO_FRAMES));
 }
diff --git a/dom/media/MediaDecoderStateMachine.h b/dom/media/MediaDecoderStateMachine.h
index 10a44709335..1580b163bfe 100644
--- a/dom/media/MediaDecoderStateMachine.h
+++ b/dom/media/MediaDecoderStateMachine.h
@@ -448,12 +448,6 @@ protected:
   // Returns true if we have less than aUsecs of undecoded data available.
   bool HasLowUndecodedData(int64_t aUsecs);
 
-  // Returns the number of unplayed usecs of audio we've got decoded and/or
-  // pushed to the hardware waiting to play. This is how much audio we can
-  // play without having to run the audio decoder. The decoder monitor
-  // must be held.
-  int64_t AudioDecodedUsecs();
-
   // Returns true when there's decoded audio waiting to play.
   // The decoder monitor must be held.
   bool HasFutureAudio();