--- a/dom/media/mediasource/MediaSourceDemuxer.cpp
+++ b/dom/media/mediasource/MediaSourceDemuxer.cpp
@@ -253,34 +253,36 @@ MediaSourceDemuxer::~MediaSourceDemuxer(
 void
 MediaSourceDemuxer::GetMozDebugReaderData(nsAString& aString)
 {
   MonitorAutoLock mon(mMonitor);
   nsAutoCString result;
   result += nsPrintfCString("Dumping data for demuxer %p:\n", this);
   if (mAudioTrack) {
     result += nsPrintfCString("\tDumping Audio Track Buffer(%s): - mLastAudioTime: %f\n"
-                              "\t\tNumSamples:%u Size:%u NextGetSampleIndex:%u NextInsertionIndex:%d\n",
+                              "\t\tNumSamples:%u Size:%u Evictable:%u NextGetSampleIndex:%u NextInsertionIndex:%d\n",
                               mAudioTrack->mAudioTracks.mInfo->mMimeType.get(),
                               mAudioTrack->mAudioTracks.mNextSampleTime.ToSeconds(),
                               mAudioTrack->mAudioTracks.mBuffers[0].Length(),
                               mAudioTrack->mAudioTracks.mSizeBuffer,
+                              mAudioTrack->Evictable(TrackInfo::kAudioTrack),
                               mAudioTrack->mAudioTracks.mNextGetSampleIndex.valueOr(-1),
                               mAudioTrack->mAudioTracks.mNextInsertionIndex.valueOr(-1));
 
     result += nsPrintfCString("\t\tBuffered: ranges=%s\n",
                               DumpTimeRanges(mAudioTrack->SafeBuffered(TrackInfo::kAudioTrack)).get());
   }
   if (mVideoTrack) {
     result += nsPrintfCString("\tDumping Video Track Buffer(%s) - mLastVideoTime: %f\n"
-                              "\t\tNumSamples:%u Size:%u NextGetSampleIndex:%u NextInsertionIndex:%d\n",
+                              "\t\tNumSamples:%u Size:%u Evictable:%u NextGetSampleIndex:%u NextInsertionIndex:%d\n",
                               mVideoTrack->mVideoTracks.mInfo->mMimeType.get(),
                               mVideoTrack->mVideoTracks.mNextSampleTime.ToSeconds(),
                               mVideoTrack->mVideoTracks.mBuffers[0].Length(),
                               mVideoTrack->mVideoTracks.mSizeBuffer,
+                              mVideoTrack->Evictable(TrackInfo::kVideoTrack),
                               mVideoTrack->mVideoTracks.mNextGetSampleIndex.valueOr(-1),
                               mVideoTrack->mVideoTracks.mNextInsertionIndex.valueOr(-1));
 
     result += nsPrintfCString("\t\tBuffered: ranges=%s\n",
                               DumpTimeRanges(mVideoTrack->SafeBuffered(TrackInfo::kVideoTrack)).get());
   }
   aString += NS_ConvertUTF8toUTF16(result);
 }

--- a/dom/media/mediasource/TrackBuffersManager.cpp
+++ b/dom/media/mediasource/TrackBuffersManager.cpp
@@ -269,25 +269,18 @@ TrackBuffersManager::EvictData(const Tim
   MOZ_ASSERT(NS_IsMainThread());
 
   if (aSize > EvictionThreshold()) {
     // We're adding more data than we can hold.
     return EvictDataResult::BUFFER_FULL;
   }
   const int64_t toEvict = GetSize() + aSize - EvictionThreshold();
 
-  uint32_t canEvict;
-  {
-    MonitorAutoLock mon(mMonitor);
-    if (HasVideo()) {
-      canEvict = mVideoTracks.mEvictionIndex.mEvictable;
-    } else {
-      canEvict = mAudioTracks.mEvictionIndex.mEvictable;
-    }
-  }
+  const uint32_t canEvict =
+    Evictable(HasVideo() ? TrackInfo::kVideoTrack : TrackInfo::kAudioTrack);
 
   MSE_DEBUG(
     "buffered=%lldkB, eviction threshold=%ukB, evict=%lldkB canevict=%ukB",
     GetSize() / 1024, EvictionThreshold() / 1024, toEvict / 1024,
     canEvict / 1024);
 
   if (toEvict <= 0) {
     mEvictionState = EvictionState::NO_EVICTION_NEEDED;
@@ -2388,16 +2381,23 @@ TrackBuffersManager::FindCurrentPosition
       return i;
     }
   }
 
   // Still not found.
   return -1;
 }
 
+uint32_t
+TrackBuffersManager::Evictable(TrackInfo::TrackType aTrack) const
+{
+  MonitorAutoLock mon(mMonitor);
+  return GetTracksData(aTrack).mEvictionIndex.mEvictable;
+}
+
 TimeUnit
 TrackBuffersManager::GetNextRandomAccessPoint(TrackInfo::TrackType aTrack,
                                               const TimeUnit& aFuzz)
 {
   MOZ_ASSERT(OnTaskQueue());
   auto& trackData = GetTracksData(aTrack);
   MOZ_ASSERT(trackData.mNextGetSampleIndex.isSome());
   const TrackBuffersManager::TrackBuffer& track = GetTrackBuffer(aTrack);

--- a/dom/media/mediasource/TrackBuffersManager.h
+++ b/dom/media/mediasource/TrackBuffersManager.h
@@ -142,16 +142,17 @@ public:
   const TrackBuffer& GetTrackBuffer(TrackInfo::TrackType aTrack);
   const media::TimeIntervals& Buffered(TrackInfo::TrackType);
   const media::TimeUnit& HighestStartTime(TrackInfo::TrackType);
   media::TimeIntervals SafeBuffered(TrackInfo::TrackType) const;
   bool IsEnded() const
   {
     return mEnded;
   }
+  uint32_t Evictable(TrackInfo::TrackType aTrack) const;
   media::TimeUnit Seek(TrackInfo::TrackType aTrack,
                        const media::TimeUnit& aTime,
                        const media::TimeUnit& aFuzz);
   uint32_t SkipToNextRandomAccessPoint(TrackInfo::TrackType aTrack,
                                        const media::TimeUnit& aTimeThreadshold,
                                        const media::TimeUnit& aFuzz,
                                        bool& aFound);
 
@@ -407,16 +408,26 @@ private:
     switch(aTrack) {
       case TrackType::kVideoTrack:
         return mVideoTracks;
       case TrackType::kAudioTrack:
       default:
         return mAudioTracks;
     }
   }
+  const TrackData& GetTracksData(TrackType aTrack) const
+  {
+    switch(aTrack) {
+      case TrackType::kVideoTrack:
+        return mVideoTracks;
+      case TrackType::kAudioTrack:
+      default:
+        return mAudioTracks;
+    }
+  }
   TrackData mVideoTracks;
   TrackData mAudioTracks;
 
   // TaskQueue methods and objects.
   AbstractThread* GetTaskQueue()
   {
     return mTaskQueue;
   }