--- a/dom/media/MediaStreamGraph.cpp
+++ b/dom/media/MediaStreamGraph.cpp
@@ -327,63 +327,60 @@ MediaStreamGraphImpl::WillUnderrun(Media
 namespace {
   // Value of mCycleMarker for unvisited streams in cycle detection.
   const uint32_t NOT_VISITED = UINT32_MAX;
   // Value of mCycleMarker for ordered streams in muted cycles.
   const uint32_t IN_MUTED_CYCLE = 1;
 } // namespace
 
 bool
-MediaStreamGraphImpl::AudioTrackPresent(bool& aNeedsAEC)
+MediaStreamGraphImpl::AudioTrackPresent()
 {
   MOZ_ASSERT(OnGraphThreadOrNotRunning());
 
   bool audioTrackPresent = false;
-  for (uint32_t i = 0; i < mStreams.Length() && audioTrackPresent == false; ++i) {
-    MediaStream* stream = mStreams[i];
-    SourceMediaStream* source = stream->AsSourceStream();
-#ifdef MOZ_WEBRTC
-    if (source && source->NeedsMixing()) {
-      aNeedsAEC = true;
-    }
-#endif
-    // If this is a AudioNodeStream, force a AudioCallbackDriver.
+  for (MediaStream* stream : mStreams) {
     if (stream->AsAudioNodeStream()) {
       audioTrackPresent = true;
-    } else {
-      for (StreamTracks::TrackIter tracks(stream->GetStreamTracks(), MediaSegment::AUDIO);
-           !tracks.IsEnded(); tracks.Next()) {
-        audioTrackPresent = true;
-      }
+      break;
     }
-    if (source) {
+
+    if (!StreamTracks::TrackIter(
+            stream->GetStreamTracks(),
+            MediaSegment::AUDIO
+          ).IsEnded()) {
+      audioTrackPresent = true;
+      break;
+    }
+
+    if (SourceMediaStream* source = stream->AsSourceStream()) {
       audioTrackPresent = source->HasPendingAudioTrack();
     }
+
+    if (audioTrackPresent) {
+      break;
+    }
   }
 
   // XXX For some reason, there are race conditions when starting an audio input where
   // we find no active audio tracks.  In any case, if we have an active audio input we
   // should not allow a switch back to a SystemClockDriver
   if (!audioTrackPresent && mInputDeviceUsers.Count() != 0) {
     NS_WARNING("No audio tracks, but full-duplex audio is enabled!!!!!");
     audioTrackPresent = true;
-#ifdef MOZ_WEBRTC
-    aNeedsAEC = true;
-#endif
   }
 
   return audioTrackPresent;
 }
 
 void
 MediaStreamGraphImpl::UpdateStreamOrder()
 {
   MOZ_ASSERT(OnGraphThreadOrNotRunning());
-  bool shouldAEC = false;
-  bool audioTrackPresent = AudioTrackPresent(shouldAEC);
+  bool audioTrackPresent = AudioTrackPresent();
 
   // Note that this looks for any audio streams, input or output, and switches to a
   // SystemClockDriver if there are none.  However, if another is already pending, let that
   // switch happen.
 
   if (!audioTrackPresent && mRealtime &&
       CurrentDriver()->AsAudioCallbackDriver()) {
     MonitorAutoLock mon(mMonitor);
@@ -890,18 +887,17 @@ MediaStreamGraphImpl::CloseAudioInputImp
   mInputWanted = false;
   AudioCallbackDriver *driver = CurrentDriver()->AsAudioCallbackDriver();
   if (driver) {
     driver->RemoveInputListener(aListener);
   }
   mAudioInputs.RemoveElement(aListener);
 
   // Switch Drivers since we're adding or removing an input (to nothing/system or output only)
-  bool shouldAEC = false;
-  bool audioTrackPresent = AudioTrackPresent(shouldAEC);
+  bool audioTrackPresent = AudioTrackPresent();
 
   MonitorAutoLock mon(mMonitor);
   if (LifecycleStateRef() == LIFECYCLE_RUNNING) {
     GraphDriver* driver;
     if (audioTrackPresent) {
       // We still have audio output
       LOG(LogLevel::Debug, ("CloseInput: output present (AudioCallback)"));
 
@@ -4139,18 +4135,17 @@ MediaStreamGraphImpl::ApplyAudioContextO
     }
   }
   // Close, suspend: check if we are going to switch to a
   // SystemAudioCallbackDriver, and pass the promise to the AudioCallbackDriver
   // if that's the case, so it can notify the content.
   // This is the same logic as in UpdateStreamOrder, but it's simpler to have it
   // here as well so we don't have to store the Promise(s) on the Graph.
   if (aOperation != AudioContextOperation::Resume) {
-    bool shouldAEC = false;
-    bool audioTrackPresent = AudioTrackPresent(shouldAEC);
+    bool audioTrackPresent = AudioTrackPresent();
 
     if (!audioTrackPresent && CurrentDriver()->AsAudioCallbackDriver()) {
       CurrentDriver()->AsAudioCallbackDriver()->
         EnqueueStreamAndPromiseForOperation(aDestinationStream, aPromise,
                                             aOperation);
 
       SystemClockDriver* driver;
       if (nextDriver) {

--- a/dom/media/MediaStreamGraphImpl.h
+++ b/dom/media/MediaStreamGraphImpl.h
@@ -317,19 +317,18 @@ public:
    * Move streams from the mStreams to mSuspendedStream if suspending/closing an
    * AudioContext, or the inverse when resuming an AudioContext.
    */
   void SuspendOrResumeStreams(dom::AudioContextOperation aAudioContextOperation,
                               const nsTArray<MediaStream*>& aStreamSet);
 
   /**
    * Determine if we have any audio tracks, or are about to add any audiotracks.
-   * Also checks if we'll need the AEC running (i.e. microphone input tracks)
    */
-  bool AudioTrackPresent(bool& aNeedsAEC);
+  bool AudioTrackPresent();
 
   /**
    * Sort mStreams so that every stream not in a cycle is after any streams
    * it depends on, and every stream in a cycle is marked as being in a cycle.
    * Also sets mIsConsumed on every stream.
    */
   void UpdateStreamOrder();