--- a/dom/media/DecoderTraits.cpp
+++ b/dom/media/DecoderTraits.cpp
@@ -48,16 +48,19 @@
 
 #include "WaveDecoder.h"
 #include "WaveDemuxer.h"
 #include "WaveReader.h"
 
 #include "ADTSDecoder.h"
 #include "ADTSDemuxer.h"
 
+#include "FlacDecoder.h"
+#include "FlacDemuxer.h"
+
 #include "nsPluginHost.h"
 #include "MediaPrefs.h"
 
 namespace mozilla
 {
 
 template <class String>
 static bool
@@ -315,16 +318,23 @@ IsAACSupportedType(const nsACString& aTy
 
 static bool
 IsWAVSupportedType(const nsACString& aType,
                    const nsAString& aCodecs = EmptyString())
 {
   return WaveDecoder::CanHandleMediaType(aType, aCodecs);
 }
 
+static bool
+IsFlacSupportedType(const nsACString& aType,
+                   const nsAString& aCodecs = EmptyString())
+{
+  return FlacDecoder::CanHandleMediaType(aType, aCodecs);
+}
+
 /* static */
 bool DecoderTraits::ShouldHandleMediaType(const char* aMIMEType,
                                           DecoderDoctorDiagnostics* aDiagnostics)
 {
   if (IsWaveType(nsDependentCString(aMIMEType))) {
     // We should not return true for Wave types, since there are some
     // Wave codecs actually in use in the wild that we don't support, and
     // we should allow those to be handled by plugins or helper apps.
@@ -395,16 +405,19 @@ DecoderTraits::CanHandleCodecsType(const
   }
 #endif
   if (IsMP3SupportedType(nsDependentCString(aMIMEType), aRequestedCodecs)) {
     return CANPLAY_YES;
   }
   if (IsAACSupportedType(nsDependentCString(aMIMEType), aRequestedCodecs)) {
     return CANPLAY_YES;
   }
+  if (IsFlacSupportedType(nsDependentCString(aMIMEType), aRequestedCodecs)) {
+    return CANPLAY_YES;
+  }
 #ifdef MOZ_OMX_DECODER
   if (IsOmxSupportedType(nsDependentCString(aMIMEType))) {
     if (nsDependentCString(aMIMEType).EqualsASCII("audio/mpeg")) {
       codecList = gMpegAudioCodecs;
 #ifdef MOZ_OMX_WEBM_DECODER
     } else if (nsDependentCString(aMIMEType).EqualsASCII("audio/webm") ||
                nsDependentCString(aMIMEType).EqualsASCII("video/webm")) {
       codecList = gOMXWebMCodecs;
@@ -488,16 +501,19 @@ DecoderTraits::CanHandleMediaType(const 
   }
 #endif
   if (IsMP3SupportedType(nsDependentCString(aMIMEType))) {
     return CANPLAY_MAYBE;
   }
   if (IsAACSupportedType(nsDependentCString(aMIMEType))) {
     return CANPLAY_MAYBE;
   }
+  if (IsFlacSupportedType(nsDependentCString(aMIMEType))) {
+    return CANPLAY_MAYBE;
+  }
 #ifdef MOZ_OMX_DECODER
   if (IsOmxSupportedType(nsDependentCString(aMIMEType))) {
     return CANPLAY_MAYBE;
   }
 #endif
 #ifdef MOZ_DIRECTSHOW
   if (DirectShowDecoder::GetSupportedCodecs(nsDependentCString(aMIMEType), nullptr)) {
     return CANPLAY_MAYBE;
@@ -545,16 +561,20 @@ InstantiateDecoder(const nsACString& aTy
   if (IsOggSupportedType(aType)) {
     decoder = new OggDecoder(aOwner);
     return decoder.forget();
   }
   if (IsWaveType(aType)) {
     decoder = new WaveDecoder(aOwner);
     return decoder.forget();
   }
+  if (IsFlacSupportedType(aType)) {
+    decoder = new FlacDecoder(aOwner);
+    return decoder.forget();
+  }
 #ifdef MOZ_OMX_DECODER
   if (IsOmxSupportedType(aType)) {
     // we are discouraging Web and App developers from using those formats in
     // gB2GOnlyTypes, thus we only allow them to be played on WebApps.
     if (IsB2GSupportOnlyType(aType)) {
       dom::HTMLMediaElement* element = aOwner->GetMediaElement();
       if (!element) {
         return nullptr;
@@ -629,16 +649,19 @@ MediaDecoderReader* DecoderTraits::Creat
     decoderReader = new MediaFormatReader(aDecoder, new mp3::MP3Demuxer(aDecoder->GetResource()));
   } else
   if (IsAACSupportedType(aType)) {
     decoderReader = new MediaFormatReader(aDecoder, new ADTSDemuxer(aDecoder->GetResource()));
   } else
   if (IsWAVSupportedType(aType)) {
     decoderReader = new MediaFormatReader(aDecoder, new WAVDemuxer(aDecoder->GetResource()));
   } else
+  if (IsFlacSupportedType(aType)) {
+    decoderReader = new MediaFormatReader(aDecoder, new FlacDemuxer(aDecoder->GetResource()));
+  } else
 #ifdef MOZ_RAW
   if (IsRawType(aType)) {
     decoderReader = new RawReader(aDecoder);
   } else
 #endif
   if (IsOggSupportedType(aType)) {
     decoderReader = MediaPrefs::OggFormatReader() ?
       static_cast<MediaDecoderReader*>(new MediaFormatReader(aDecoder, new OggDemuxer(aDecoder->GetResource()))) :
@@ -696,15 +719,16 @@ bool DecoderTraits::IsSupportedInVideoDo
 #ifdef MOZ_ANDROID_OMX
     (MediaDecoder::IsAndroidMediaPluginEnabled() && IsAndroidMediaType(aType)) ||
 #endif
 #ifdef MOZ_FMP4
     IsMP4SupportedType(aType, /* DecoderDoctorDiagnostics* */ nullptr) ||
 #endif
     IsMP3SupportedType(aType) ||
     IsAACSupportedType(aType) ||
+    IsFlacSupportedType(aType) ||
 #ifdef MOZ_DIRECTSHOW
     IsDirectShowSupportedType(aType) ||
 #endif
     false;
 }
 
 } // namespace mozilla

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -543,16 +543,17 @@ pref("media.mediasource.mp4.enabled", tr
 pref("media.mediasource.webm.enabled", false);
 #else
 pref("media.mediasource.webm.enabled", true);
 #endif
 pref("media.mediasource.webm.audio.enabled", true);
 
 // Use new MediaFormatReader architecture for plain ogg.
 pref("media.format-reader.ogg", true);
+pref("media.flac.enabled", true);
 
 pref("media.benchmark.vp9.threshold", 150);
 pref("media.benchmark.frames", 300);
 pref("media.benchmark.timeout", 1000);
 
 #ifdef MOZ_WEBSPEECH
 pref("media.webspeech.recognition.enable", false);
 pref("media.webspeech.synth.enabled", false);