diff --git a/build.gradle b/build.gradle
index d39a6c271bab..70eed4215840 100644
--- a/build.gradle
+++ b/build.gradle
@@ -67,10 +67,6 @@ if ('multi' == System.env.AB_CD) {
     // dependency chain to fail, since multi isn't a real locale.  To avoid
     // this, if Gradle is invoked with AB_CD=multi, we don't invoke Make at all.
     task generateCodeAndResources()
-} else if (System.env.IS_LANGUAGE_REPACK == '1') {
-    // Single-locale l10n repacks set `IS_LANGUAGE_REPACK=1` and handle resource
-    // and code generation themselves.
-    task generateCodeAndResources()
 } else {
     task generateCodeAndResources(type:Exec) {
         workingDir "${topobjdir}"
diff --git a/dom/html/HTMLMediaElement.cpp b/dom/html/HTMLMediaElement.cpp
index b6e43de999b7..4abfde1e7b75 100644
--- a/dom/html/HTMLMediaElement.cpp
+++ b/dom/html/HTMLMediaElement.cpp
@@ -1486,11 +1486,9 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(HTMLMediaElement, nsGenericHTM
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mAudioTrackList)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mVideoTrackList)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mMediaKeys)
-  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mIncomingMediaKeys)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSelectedVideoStreamTrack)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPendingPlayPromises)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSeekDOMPromise)
-  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSetMediaKeysDOMPromise)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(HTMLMediaElement, nsGenericHTMLElement)
@@ -1517,11 +1515,9 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(HTMLMediaElement, nsGenericHTMLE
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mAudioTrackList)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mVideoTrackList)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mMediaKeys)
-  NS_IMPL_CYCLE_COLLECTION_UNLINK(mIncomingMediaKeys)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mSelectedVideoStreamTrack)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mPendingPlayPromises)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mSeekDOMPromise)
-  NS_IMPL_CYCLE_COLLECTION_UNLINK(mSetMediaKeysDOMPromise)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(HTMLMediaElement)
@@ -1727,7 +1723,6 @@ void HTMLMediaElement::ShutdownDecoder()
 {
   RemoveMediaElementFromURITable();
   NS_ASSERTION(mDecoder, "Must have decoder to shut down");
-  mSetCDMRequest.DisconnectIfExists();
   mWaitingForKeyListener.DisconnectIfExists();
   if (mMediaSource) {
     mMediaSource->CompletePendingTransactions();
@@ -3991,7 +3986,6 @@ HTMLMediaElement::HTMLMediaElement(already_AddRefed<mozilla::dom::NodeInfo>& aNo
     mPlaybackRate(1.0),
     mPreservesPitch(true),
     mPlayed(new TimeRanges(ToSupports(OwnerDoc()))),
-    mAttachingMediaKey(false),
     mCurrentPlayRangeStart(-1.0),
     mLoadedDataFired(false),
     mAutoplaying(true),
@@ -7022,180 +7016,6 @@ HTMLMediaElement::ContainsRestrictedContent()
   return GetMediaKeys() != nullptr;
 }
 
-void
-HTMLMediaElement::SetCDMProxyFailure(const MediaResult& aResult)
-{
-  LOG(LogLevel::Debug, ("%s", __func__));
-  MOZ_ASSERT(mSetMediaKeysDOMPromise);
-
-  ResetSetMediaKeysTempVariables();
-
-  mSetMediaKeysDOMPromise->MaybeReject(aResult.Code(), aResult.Message());
-}
-
-void
-HTMLMediaElement::RemoveMediaKeys()
-{
-  LOG(LogLevel::Debug, ("%s", __func__));
-  // 5.2.3 Stop using the CDM instance represented by the mediaKeys attribute
-  // to decrypt media data and remove the association with the media element.
-  mMediaKeys->Unbind();
-  mMediaKeys = nullptr;
-}
-
-bool
-HTMLMediaElement::TryRemoveMediaKeysAssociation()
-{
-  MOZ_ASSERT(mMediaKeys);
-  LOG(LogLevel::Debug, ("%s", __func__));
-  // 5.2.1 If the user agent or CDM do not support removing the association,
-  // let this object's attaching media keys value be false and reject promise
-  // with a new DOMException whose name is NotSupportedError.
-  // 5.2.2 If the association cannot currently be removed, let this object's
-  // attaching media keys value be false and reject promise with a new
-  // DOMException whose name is InvalidStateError.
-  if (mDecoder) {
-    RefPtr<HTMLMediaElement> self = this;
-    mDecoder->SetCDMProxy(nullptr)
-      ->Then(mAbstractMainThread,
-             __func__,
-             [self]() {
-               self->mSetCDMRequest.Complete();
-
-               self->RemoveMediaKeys();
-               if (self->AttachNewMediaKeys()) {
-                 // No incoming MediaKeys object or MediaDecoder is not created yet.
-                 self->MakeAssociationWithCDMResolved();
-               }
-             },
-             [self](const MediaResult& aResult) {
-               self->mSetCDMRequest.Complete();
-               // 5.2.4 If the preceding step failed, let this object's attaching media
-               // keys value be false and reject promise with a new DOMException whose
-               // name is the appropriate error name.
-               self->SetCDMProxyFailure(aResult);
-             })
-      ->Track(mSetCDMRequest);
-    return false;
-  }
-
-  RemoveMediaKeys();
-  return true;
-}
-
-bool
-HTMLMediaElement::DetachExistingMediaKeys()
-{
-  LOG(LogLevel::Debug, ("%s", __func__));
-  MOZ_ASSERT(mSetMediaKeysDOMPromise);
-  // 5.1 If mediaKeys is not null, CDM instance represented by mediaKeys is
-  // already in use by another media element, and the user agent is unable
-  // to use it with this element, let this object's attaching media keys
-  // value be false and reject promise with a new DOMException whose name
-  // is QuotaExceededError.
-  if (mIncomingMediaKeys && mIncomingMediaKeys->IsBoundToMediaElement()) {
-    SetCDMProxyFailure(MediaResult(
-      NS_ERROR_DOM_QUOTA_EXCEEDED_ERR,
-      "MediaKeys object is already bound to another HTMLMediaElement"));
-    return false;
-  }
-
-  // 5.2 If the mediaKeys attribute is not null, run the following steps:
-  if (mMediaKeys) {
-    return TryRemoveMediaKeysAssociation();
-  }
-  return true;
-}
-
-void
-HTMLMediaElement::MakeAssociationWithCDMResolved()
-{
-  LOG(LogLevel::Debug, ("%s", __func__));
-  MOZ_ASSERT(mSetMediaKeysDOMPromise);
-
-  // 5.4 Set the mediaKeys attribute to mediaKeys.
-  mMediaKeys = mIncomingMediaKeys;
-  // 5.5 Let this object's attaching media keys value be false.
-  ResetSetMediaKeysTempVariables();
-  // 5.6 Resolve promise.
-  mSetMediaKeysDOMPromise->MaybeResolveWithUndefined();
-  mSetMediaKeysDOMPromise = nullptr;
-}
-
-bool
-HTMLMediaElement::TryMakeAssociationWithCDM(CDMProxy* aProxy)
-{
-  LOG(LogLevel::Debug, ("%s", __func__));
-  MOZ_ASSERT(aProxy);
-
-  // 5.3.3 Queue a task to run the "Attempt to Resume Playback If Necessary"
-  // algorithm on the media element.
-  // Note: Setting the CDMProxy on the MediaDecoder will unblock playback.
-  if (mDecoder) {
-    // CDMProxy is set asynchronously in MediaFormatReader, once it's done,
-    // HTMLMediaElement should resolve or reject the DOM promise.
-    RefPtr<HTMLMediaElement> self = this;
-    mDecoder->SetCDMProxy(aProxy)
-      ->Then(mAbstractMainThread,
-             __func__,
-             [self]() {
-               self->mSetCDMRequest.Complete();
-               self->MakeAssociationWithCDMResolved();
-             },
-             [self](const MediaResult& aResult) {
-               self->mSetCDMRequest.Complete();
-               self->SetCDMProxyFailure(aResult);
-             })
-      ->Track(mSetCDMRequest);
-    return false;
-  }
-  return true;
-}
-
-bool
-HTMLMediaElement::AttachNewMediaKeys()
-{
-  LOG(LogLevel::Debug,
-      ("%s incoming MediaKeys(%p)", __func__, mIncomingMediaKeys.get()));
-  MOZ_ASSERT(mSetMediaKeysDOMPromise);
-
-  // 5.3. If mediaKeys is not null, run the following steps:
-  if (mIncomingMediaKeys) {
-    auto cdmProxy = mIncomingMediaKeys->GetCDMProxy();
-    if (!cdmProxy) {
-      SetCDMProxyFailure(MediaResult(
-        NS_ERROR_DOM_INVALID_STATE_ERR,
-        "CDM crashed before binding MediaKeys object to HTMLMediaElement"));
-      return false;
-    }
-
-    // 5.3.1 Associate the CDM instance represented by mediaKeys with the
-    // media element for decrypting media data.
-    if (NS_FAILED(mIncomingMediaKeys->Bind(this))) {
-      // 5.3.2 If the preceding step failed, run the following steps:
-
-      // 5.3.2.1 Set the mediaKeys attribute to null.
-      mMediaKeys = nullptr;
-      // 5.3.2.2 Let this object's attaching media keys value be false.
-      // 5.3.2.3 Reject promise with a new DOMException whose name is
-      // the appropriate error name.
-      SetCDMProxyFailure(
-        MediaResult(NS_ERROR_DOM_INVALID_STATE_ERR,
-                    "Failed to bind MediaKeys object to HTMLMediaElement"));
-      return false;
-    }
-    return TryMakeAssociationWithCDM(cdmProxy);
-  }
-  return true;
-}
-
-void
-HTMLMediaElement::ResetSetMediaKeysTempVariables()
-{
-  mAttachingMediaKey = false;
-  mIncomingMediaKeys = nullptr;
-}
-
 already_AddRefed<Promise>
 HTMLMediaElement::SetMediaKeys(mozilla::dom::MediaKeys* aMediaKeys,
                                ErrorResult& aRv)
@@ -7227,31 +7047,89 @@ HTMLMediaElement::SetMediaKeys(mozilla::dom::MediaKeys* aMediaKeys,
     return promise.forget();
   }
 
+  // Note: Our attaching code is synchronous, so we can skip the following steps.
+
   // 2. If this object's attaching media keys value is true, return a
   // promise rejected with a new DOMException whose name is InvalidStateError.
-  if (mAttachingMediaKey) {
-    promise->MaybeReject(
-      NS_ERROR_DOM_INVALID_STATE_ERR,
-      NS_LITERAL_CSTRING("A MediaKeys object is in attaching operation."));
-    return promise.forget();
-  }
-
   // 3. Let this object's attaching media keys value be true.
-  mAttachingMediaKey = true;
-  mIncomingMediaKeys = aMediaKeys;
-
   // 4. Let promise be a new promise.
-  mSetMediaKeysDOMPromise = promise;
-
   // 5. Run the following steps in parallel:
 
-  // 5.1 & 5.2 & 5.3
-  if (!DetachExistingMediaKeys() || !AttachNewMediaKeys()) {
+  // 5.1 If mediaKeys is not null, CDM instance represented by mediaKeys is
+  // already in use by another media element, and the user agent is unable
+  // to use it with this element, let this object's attaching media keys
+  // value be false and reject promise with a new DOMException whose name
+  // is QuotaExceededError.
+  if (aMediaKeys && aMediaKeys->IsBoundToMediaElement()) {
+    promise->MaybeReject(NS_ERROR_DOM_QUOTA_EXCEEDED_ERR,
+      NS_LITERAL_CSTRING("MediaKeys object is already bound to another HTMLMediaElement"));
     return promise.forget();
   }
 
-  // 5.4, 5.5, 5.6
-  MakeAssociationWithCDMResolved();
+  // 5.2 If the mediaKeys attribute is not null, run the following steps:
+  if (mMediaKeys) {
+    // 5.2.1 If the user agent or CDM do not support removing the association,
+    // let this object's attaching media keys value be false and reject promise
+    // with a new DOMException whose name is NotSupportedError.
+
+    // 5.2.2 If the association cannot currently be removed, let this object's
+    // attaching media keys value be false and reject promise with a new
+    // DOMException whose name is InvalidStateError.
+    if (mDecoder) {
+      // We don't support swapping out the MediaKeys once we've started to
+      // setup the playback pipeline. Note this also means we don't need to worry
+      // about handling disassociating the MediaKeys from the MediaDecoder.
+      promise->MaybeReject(NS_ERROR_DOM_INVALID_STATE_ERR,
+        NS_LITERAL_CSTRING("Can't change MediaKeys on HTMLMediaElement after load has started"));
+      return promise.forget();
+    }
+
+    // 5.2.3 Stop using the CDM instance represented by the mediaKeys attribute
+    // to decrypt media data and remove the association with the media element.
+    mMediaKeys->Unbind();
+    mMediaKeys = nullptr;
+
+    // 5.2.4 If the preceding step failed, let this object's attaching media
+    // keys value be false and reject promise with a new DOMException whose
+    // name is the appropriate error name.
+  }
+
+  // 5.3. If mediaKeys is not null, run the following steps:
+  if (aMediaKeys) {
+    if (!aMediaKeys->GetCDMProxy()) {
+      promise->MaybeReject(NS_ERROR_DOM_INVALID_STATE_ERR,
+        NS_LITERAL_CSTRING("CDM crashed before binding MediaKeys object to HTMLMediaElement"));
+      return promise.forget();
+    }
+
+    // 5.3.1 Associate the CDM instance represented by mediaKeys with the
+    // media element for decrypting media data.
+    if (NS_FAILED(aMediaKeys->Bind(this))) {
+      // 5.3.2 If the preceding step failed, run the following steps:
+      // 5.3.2.1 Set the mediaKeys attribute to null.
+      mMediaKeys = nullptr;
+      // 5.3.2.2 Let this object's attaching media keys value be false.
+      // 5.3.2.3 Reject promise with a new DOMException whose name is
+      // the appropriate error name.
+      promise->MaybeReject(NS_ERROR_DOM_INVALID_STATE_ERR,
+                           NS_LITERAL_CSTRING("Failed to bind MediaKeys object to HTMLMediaElement"));
+      return promise.forget();
+    }
+    // 5.3.3 Queue a task to run the "Attempt to Resume Playback If Necessary"
+    // algorithm on the media element.
+    // Note: Setting the CDMProxy on the MediaDecoder will unblock playback.
+    if (mDecoder) {
+      mDecoder->SetCDMProxy(aMediaKeys->GetCDMProxy());
+    }
+  }
+
+  // 5.4 Set the mediaKeys attribute to mediaKeys.
+  mMediaKeys = aMediaKeys;
+
+  // 5.5 Let this object's attaching media keys value be false.
+
+  // 5.6 Resolve promise.
+  promise->MaybeResolveWithUndefined();
 
   // 6. Return promise.
   return promise.forget();
diff --git a/dom/html/HTMLMediaElement.h b/dom/html/HTMLMediaElement.h
index 5a9a1b196f6b..f0eee1e59b2a 100644
--- a/dom/html/HTMLMediaElement.h
+++ b/dom/html/HTMLMediaElement.h
@@ -12,7 +12,6 @@
 #include "MediaEventSource.h"
 #include "SeekTarget.h"
 #include "MediaDecoderOwner.h"
-#include "MediaPromiseDefs.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsIObserver.h"
 #include "mozilla/CORSMode.h"
@@ -1333,15 +1332,6 @@ protected:
                                           const nsAttrValueOrString& aValue,
                                           bool aNotify) override;
 
-  bool DetachExistingMediaKeys();
-  bool TryRemoveMediaKeysAssociation();
-  void RemoveMediaKeys();
-  bool AttachNewMediaKeys();
-  bool TryMakeAssociationWithCDM(CDMProxy* aProxy);
-  void MakeAssociationWithCDMResolved();
-  void SetCDMProxyFailure(const MediaResult& aResult);
-  void ResetSetMediaKeysTempVariables();
-
   // The current decoder. Load() has been called on this decoder.
   // At most one of mDecoder and mSrcStream can be non-null.
   RefPtr<MediaDecoder> mDecoder;
@@ -1544,12 +1534,6 @@ protected:
 
   // Encrypted Media Extension media keys.
   RefPtr<MediaKeys> mMediaKeys;
-  RefPtr<MediaKeys> mIncomingMediaKeys;
-  // The dom promise is used for HTMLMediaElement::SetMediaKeys.
-  RefPtr<DetailedPromise> mSetMediaKeysDOMPromise;
-  // Used to indicate if the MediaKeys attaching operation is on-going or not.
-  bool mAttachingMediaKey;
-  MozPromiseRequestHolder<SetCDMPromise> mSetCDMRequest;
 
   // Stores the time at the start of the current 'played' range.
   double mCurrentPlayRangeStart;
diff --git a/dom/media/MediaDecoder.cpp b/dom/media/MediaDecoder.cpp
index 372fccee243d..f5a42c6ff954 100644
--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -1423,15 +1423,18 @@ MediaDecoder::CanPlayThrough()
   return val;
 }
 
-RefPtr<SetCDMPromise>
+void
 MediaDecoder::SetCDMProxy(CDMProxy* aProxy)
 {
   MOZ_ASSERT(NS_IsMainThread());
-  return InvokeAsync<RefPtr<CDMProxy>>(mReader->OwnerThread(),
-                                       mReader.get(),
-                                       __func__,
-                                       &MediaFormatReader::SetCDMProxy,
-                                       aProxy);
+  RefPtr<CDMProxy> proxy = aProxy;
+  RefPtr<MediaFormatReader> reader = mReader;
+  nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction(
+    "MediaFormatReader::SetCDMProxy",
+    [reader, proxy]() {
+    reader->SetCDMProxy(proxy);
+    });
+  mReader->OwnerThread()->Dispatch(r.forget());
 }
 
 bool
diff --git a/dom/media/MediaDecoder.h b/dom/media/MediaDecoder.h
index 8030ea5bb9b7..fbdc0a22d620 100644
--- a/dom/media/MediaDecoder.h
+++ b/dom/media/MediaDecoder.h
@@ -12,7 +12,6 @@
 #include "MediaDecoderOwner.h"
 #include "MediaEventSource.h"
 #include "MediaMetadataManager.h"
-#include "MediaPromiseDefs.h"
 #include "MediaResource.h"
 #include "MediaStatistics.h"
 #include "MediaStreamGraph.h"
@@ -356,7 +355,7 @@ private:
     return mAbstractMainThread;
   }
 
-  RefPtr<SetCDMPromise> SetCDMProxy(CDMProxy* aProxy);
+  void SetCDMProxy(CDMProxy* aProxy);
 
   void EnsureTelemetryReported();
 
diff --git a/dom/media/MediaFormatReader.cpp b/dom/media/MediaFormatReader.cpp
index 10bee6876221..082580daf1ad 100644
--- a/dom/media/MediaFormatReader.cpp
+++ b/dom/media/MediaFormatReader.cpp
@@ -1228,10 +1228,6 @@ MediaFormatReader::Shutdown()
   mMetadataPromise.RejectIfExists(NS_ERROR_DOM_MEDIA_CANCELED, __func__);
   mSeekPromise.RejectIfExists(NS_ERROR_DOM_MEDIA_CANCELED, __func__);
   mSkipRequest.DisconnectIfExists();
-  mSetCDMPromise.RejectIfExists(
-    MediaResult(NS_ERROR_DOM_INVALID_STATE_ERR,
-                "MediaFormatReader is shutting down"),
-    __func__);
 
   if (mAudio.HasPromise()) {
     mAudio.RejectPromise(NS_ERROR_DOM_MEDIA_CANCELED, __func__);
@@ -1322,101 +1318,23 @@ MediaFormatReader::Init()
   return NS_OK;
 }
 
-bool
-MediaFormatReader::ResolveSetCDMPromiseIfDone(TrackType aTrack)
-{
-  // When a CDM proxy is set, MFR would shutdown the existing MediaDataDecoder
-  // and would create new one for specific track in the next Update.
-  MOZ_ASSERT(OnTaskQueue());
-
-  if (mSetCDMPromise.IsEmpty()) {
-    return true;
-  }
-
-  MOZ_ASSERT(mCDMProxy);
-  if (mSetCDMForTracks.contains(aTrack)) {
-    mSetCDMForTracks -= aTrack;
-  }
-
-  if (mSetCDMForTracks.isEmpty()) {
-    LOGV("%s : Done ", __func__);
-    mSetCDMPromise.Resolve(/* aIgnored = */ true, __func__);
-    ScheduleUpdate(TrackInfo::kAudioTrack);
-    ScheduleUpdate(TrackInfo::kVideoTrack);
-    return true;
-  }
-  LOGV("%s : %s track is ready.", __func__, TrackTypeToStr(aTrack));
-  return false;
-}
-
 void
-MediaFormatReader::PrepareToSetCDMForTrack(TrackType aTrack)
-{
-  MOZ_ASSERT(OnTaskQueue());
-  LOGV("%s : %s", __func__, TrackTypeToStr(aTrack));
-
-  mSetCDMForTracks += aTrack;
-  if (mCDMProxy) {
-    // An old cdm proxy exists, so detaching old cdm proxy by shutting down
-    // MediaDataDecoder.
-    ShutdownDecoder(aTrack);
-  }
-  ScheduleUpdate(aTrack);
-}
-
-bool
-MediaFormatReader::IsDecoderWaitingForCDM(TrackType aTrack)
-{
-  MOZ_ASSERT(OnTaskQueue());
-  return IsEncrypted() && mSetCDMForTracks.contains(aTrack) && !mCDMProxy;
-}
-
-RefPtr<SetCDMPromise>
 MediaFormatReader::SetCDMProxy(CDMProxy* aProxy)
 {
-  MOZ_ASSERT(OnTaskQueue());
-  LOGV("SetCDMProxy (%p)", aProxy);
-
-  if (mShutdown) {
-    return SetCDMPromise::CreateAndReject(
-      MediaResult(NS_ERROR_DOM_INVALID_STATE_ERR,
-                  "MediaFormatReader is shutting down"),
-      __func__);
-  }
-
-  mSetCDMPromise.RejectIfExists(
-    MediaResult(NS_ERROR_DOM_INVALID_STATE_ERR,
-                "Another new CDM proxy is being set."),
-    __func__);
-
-  // Shutdown all decoders as switching CDM proxy indicates that it's
-  // inappropriate for the existing decoders to continue decoding via the old
-  // CDM proxy.
-  if (HasAudio()) {
-    PrepareToSetCDMForTrack(TrackInfo::kAudioTrack);
-  }
-  if (HasVideo()) {
-    PrepareToSetCDMForTrack(TrackInfo::kVideoTrack);
-  }
-
-  mCDMProxy = aProxy;
-
-  if (IsEncrypted() && !mCDMProxy) {
-    // Release old PDMFactory which contains an EMEDecoderModule.
-    mPlatform = nullptr;
-  }
-
-  if (!mInitDone || mSetCDMForTracks.isEmpty() || !mCDMProxy) {
-    // 1) MFR is not initialized yet or
-    // 2) Demuxer is initialized without active audio and video or
-    // 3) A null cdm proxy is set
-    // the promise can be resolved directly.
-    mSetCDMForTracks.clear();
-    return SetCDMPromise::CreateAndResolve(/* aIgnored = */ true, __func__);
-  }
-
-  RefPtr<SetCDMPromise> p = mSetCDMPromise.Ensure(__func__);
-  return p;
+  RefPtr<CDMProxy> proxy = aProxy;
+  RefPtr<MediaFormatReader> self = this;
+  nsCOMPtr<nsIRunnable> r =
+    NS_NewRunnableFunction("MediaFormatReader::SetCDMProxy", [=]() {
+      MOZ_ASSERT(self->OnTaskQueue());
+      self->mCDMProxy = proxy;
+      if (HasAudio()) {
+        self->ScheduleUpdate(TrackInfo::kAudioTrack);
+      }
+      if (HasVideo()) {
+        self->ScheduleUpdate(TrackInfo::kVideoTrack);
+      }
+    });
+  OwnerThread()->Dispatch(r.forget());
 }
 
 bool
@@ -2473,13 +2391,6 @@ MediaFormatReader::Update(TrackType aTrack)
       LOG("Rejecting %s promise: WAITING_FOR_DATA due to waiting for key",
           TrackTypeToStr(aTrack));
       decoder.RejectPromise(NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA, __func__);
-    } else if (IsDecoderWaitingForCDM(aTrack)) {
-      // Rejecting the promise could lead to entering buffering state for MDSM,
-      // once a qualified(with the same key system and sessions created by the
-      // same InitData) new cdm proxy is set, decoding can be resumed.
-      LOG("Rejecting %s promise: WAITING_FOR_DATA due to waiting for CDM",
-          TrackTypeToStr(aTrack));
-      decoder.RejectPromise(NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA, __func__);
     }
   }
 
@@ -2537,7 +2448,7 @@ MediaFormatReader::Update(TrackType aTrack)
 
   LOGV("Update(%s) ni=%d no=%d in:%" PRIu64 " out:%" PRIu64
        " qs=%u decoding:%d flushing:%d desc:%s pending:%u waiting:%d eos:%d "
-       "ds:%d sid:%u waitcdm:%d",
+       "ds:%d sid:%u",
        TrackTypeToStr(aTrack),
        needInput,
        needOutput,
@@ -2551,10 +2462,9 @@ MediaFormatReader::Update(TrackType aTrack)
        decoder.mWaitingForData,
        decoder.mDemuxEOS,
        int32_t(decoder.mDrainState),
-       decoder.mLastStreamSourceID,
-       IsDecoderWaitingForCDM(aTrack));
+       decoder.mLastStreamSourceID);
 
-  if (IsWaitingOnCDMResource() || !ResolveSetCDMPromiseIfDone(aTrack)) {
+  if (IsWaitingOnCDMResource()) {
     // If the content is encrypted, MFR won't start to create decoder until
     // CDMProxy is set.
     return;
@@ -2564,9 +2474,7 @@ MediaFormatReader::Update(TrackType aTrack)
        (!decoder.mTimeThreshold || decoder.mTimeThreshold.ref().mWaiting)) ||
       (decoder.mWaitingForKey && decoder.mDecodeRequest.Exists())) {
     // Nothing more we can do at present.
-    LOGV("Still waiting for data or key. data(%d)/key(%d)",
-         decoder.mWaitingForData,
-         decoder.mWaitingForKey);
+    LOGV("Still waiting for data or key.");
     return;
   }
 
diff --git a/dom/media/MediaFormatReader.h b/dom/media/MediaFormatReader.h
index 9446aea75d5b..822b22cf3c0e 100644
--- a/dom/media/MediaFormatReader.h
+++ b/dom/media/MediaFormatReader.h
@@ -18,7 +18,6 @@
 #include "MediaDataDemuxer.h"
 #include "MediaMetadataManager.h"
 #include "MediaPrefs.h"
-#include "MediaPromiseDefs.h"
 #include "nsAutoPtr.h"
 #include "PDMFactory.h"
 #include "SeekTarget.h"
@@ -92,6 +91,7 @@ class MediaFormatReader final
   static const bool IsExclusive = true;
   typedef TrackInfo::TrackType TrackType;
   typedef MozPromise<bool, MediaResult, IsExclusive> NotifyDataArrivedPromise;
+
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaFormatReader)
 
 public:
@@ -194,7 +194,7 @@ public:
   // cases like MSE.
   bool UseBufferingHeuristics() const { return mTrackDemuxersMayBlock; }
 
-  RefPtr<SetCDMPromise> SetCDMProxy(CDMProxy* aProxy);
+  void SetCDMProxy(CDMProxy* aProxy);
 
   // Returns a string describing the state of the decoder data.
   // Used for debugging purposes.
@@ -792,12 +792,6 @@ private:
 
   // Used in bug 1393399 for telemetry.
   const MediaDecoderOwnerID mMediaDecoderOwnerID;
-
-  bool ResolveSetCDMPromiseIfDone(TrackType aTrack);
-  void PrepareToSetCDMForTrack(TrackType aTrack);
-  MozPromiseHolder<SetCDMPromise> mSetCDMPromise;
-  TrackSet mSetCDMForTracks{};
-  bool IsDecoderWaitingForCDM(TrackType aTrack);
 };
 
 } // namespace mozilla
diff --git a/dom/media/MediaPromiseDefs.h b/dom/media/MediaPromiseDefs.h
deleted file mode 100644
index 59654923b832..000000000000
--- a/dom/media/MediaPromiseDefs.h
+++ /dev/null
@@ -1,19 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* vim:set ts=2 sw=2 sts=2 et cindent: */
-/* 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 MediaPromiseDefs_h_
-#define MediaPromiseDefs_h_
-
-#include "MediaResult.h"
-#include "mozilla/MozPromise.h"
-
-namespace mozilla {
-
-using SetCDMPromise =
-  MozPromise<bool /* aIgnored */, MediaResult, /* IsExclusive */ true>;
-
-} // namespace mozilla
-
-#endif
diff --git a/dom/media/moz.build b/dom/media/moz.build
index b61e9df35c4c..551067a6b5e0 100644
--- a/dom/media/moz.build
+++ b/dom/media/moz.build
@@ -121,7 +121,6 @@ EXPORTS += [
     'MediaMetadataManager.h',
     'MediaMIMETypes.h',
     'MediaPrefs.h',
-    'MediaPromiseDefs.h',
     'MediaQueue.h',
     'MediaRecorder.h',
     'MediaResource.h',
diff --git a/dom/media/platforms/wmf/DXVA2Manager.cpp b/dom/media/platforms/wmf/DXVA2Manager.cpp
index 112aa40cfb38..575d4d8b1717 100644
--- a/dom/media/platforms/wmf/DXVA2Manager.cpp
+++ b/dom/media/platforms/wmf/DXVA2Manager.cpp
@@ -929,7 +929,7 @@ D3D11DXVA2Manager::CopyToImage(IMFSample* aVideoSample,
   NS_ENSURE_TRUE(client, E_FAIL);
 
   RefPtr<IDXGIKeyedMutex> mutex;
-  HRESULT hr;
+  HRESULT hr = S_OK;
   RefPtr<ID3D11Texture2D> texture = image->GetTexture();
 
   texture->QueryInterface((IDXGIKeyedMutex**)getter_AddRefs(mutex));
@@ -987,7 +987,9 @@ D3D11DXVA2Manager::CopyToImage(IMFSample* aVideoSample,
     // It appears some race-condition may allow us to arrive here even when mSyncObject
     // is null. It's better to avoid that crash.
     client->SyncWithObject(mSyncObject);
-    mSyncObject->Synchronize();
+    if (!mSyncObject->Synchronize(true)) {
+      return DXGI_ERROR_DEVICE_RESET;
+    }
   }
 
   image.forget(aOutImage);
diff --git a/dom/media/platforms/wmf/WMFMediaDataDecoder.cpp b/dom/media/platforms/wmf/WMFMediaDataDecoder.cpp
index 65ec9598ae14..405bd467bc09 100644
--- a/dom/media/platforms/wmf/WMFMediaDataDecoder.cpp
+++ b/dom/media/platforms/wmf/WMFMediaDataDecoder.cpp
@@ -115,6 +115,10 @@ WMFMediaDataDecoder::ProcessError(HRESULT aError, const char* aReason)
     SendTelemetry(aError);
     mRecordedError = true;
   }
+
+  //TODO: For the error DXGI_ERROR_DEVICE_RESET, we could return
+  // NS_ERROR_DOM_MEDIA_NEED_NEW_DECODER to get the latest device. Maybe retry
+  // up to 3 times.
   return DecodePromise::CreateAndReject(
     MediaResult(NS_ERROR_DOM_MEDIA_DECODE_ERR,
                 RESULT_DETAIL("%s:%x", aReason, aError)),
@@ -127,7 +131,10 @@ WMFMediaDataDecoder::ProcessDecode(MediaRawData* aSample)
   DecodedData results;
   HRESULT hr = mMFTManager->Input(aSample);
   if (hr == MF_E_NOTACCEPTING) {
-    ProcessOutput(results);
+    hr = ProcessOutput(results);
+    if (FAILED(hr)) {
+      return ProcessError(hr, "MFTManager::Output(1)");
+    }
     hr = mMFTManager->Input(aSample);
   }
 
@@ -143,7 +150,7 @@ WMFMediaDataDecoder::ProcessDecode(MediaRawData* aSample)
   if (SUCCEEDED(hr) || hr == MF_E_TRANSFORM_NEED_MORE_INPUT) {
     return DecodePromise::CreateAndResolve(Move(results), __func__);
   }
-  return ProcessError(hr, "MFTManager::Output");
+  return ProcessError(hr, "MFTManager::Output(2)");
 }
 
 HRESULT
diff --git a/dom/media/test/bipbop_225w_175kbps.mp4^headers^ b/dom/media/test/bipbop_225w_175kbps.mp4^headers^
deleted file mode 100644
index 4030ea1d3ddb..000000000000
--- a/dom/media/test/bipbop_225w_175kbps.mp4^headers^
+++ /dev/null
@@ -1 +0,0 @@
-Cache-Control: no-store
diff --git a/dom/media/test/crashtests/crashtests.list b/dom/media/test/crashtests/crashtests.list
index 5f2d363bb92f..3fde1fdb2387 100644
--- a/dom/media/test/crashtests/crashtests.list
+++ b/dom/media/test/crashtests/crashtests.list
@@ -108,6 +108,6 @@ load oscillator-ended-1.html
 load oscillator-ended-2.html
 skip-if(Android&&AndroidVersion=='22') load video-replay-after-audio-end.html # bug 1315125, bug 1358876
 # This needs to run at the end to avoid leaking busted state into other tests.
-load 691096-1.html
+skip-if(Android) load 691096-1.html # Bug 1365451
 load 1236639.html
 test-pref(media.navigator.permission.disabled,true) load 1388372.html
diff --git a/dom/media/test/mochitest.ini b/dom/media/test/mochitest.ini
index a505b97e1864..3fb833716700 100644
--- a/dom/media/test/mochitest.ini
+++ b/dom/media/test/mochitest.ini
@@ -74,8 +74,6 @@ support-files =
   bipbop-cenc-videoinit.mp4^headers^
   bipbop-cenc-video-10s.mp4
   bipbop-cenc-video-10s.mp4^headers^
-  bipbop_225w_175kbps.mp4
-  bipbop_225w_175kbps.mp4^headers^
   bipbop_225w_175kbps-cenc-audio-key1-1.m4s
   bipbop_225w_175kbps-cenc-audio-key1-1.m4s^headers^
   bipbop_225w_175kbps-cenc-audio-key1-2.m4s
@@ -760,8 +758,6 @@ skip-if = toolkit == 'android' # bug 1149374
 skip-if = toolkit == 'android' # bug 1149374
 [test_eme_detach_media_keys.html]
 skip-if = toolkit == 'android' # bug 1149374
-[test_eme_detach_reattach_same_mediakeys_during_playback.html]
-skip-if = toolkit == 'android' # bug 1149374
 [test_eme_initDataTypes.html]
 skip-if = toolkit == 'android' # bug 1149374
 [test_eme_missing_pssh.html]
@@ -787,8 +783,6 @@ skip-if = toolkit == 'android' # bug 1149374
 [test_eme_stream_capture_blocked_case3.html]
 tags=msg capturestream
 skip-if = toolkit == 'android' # bug 1149374
-[test_eme_unsetMediaKeys_then_capture.html]
-skip-if = toolkit == 'android' # bug 1149374
 [test_eme_waitingforkey.html]
 skip-if = toolkit == 'android' # bug 1149374
 [test_empty_resource.html]
@@ -849,6 +843,7 @@ tags=msg
 skip-if = android_version == '17' # android(bug 1232305)
 tags=msg
 [test_mediarecorder_record_addtracked_stream.html]
+skip-if = toolkit == 'android' # Bug 1408241
 tags=msg capturestream
 [test_mediarecorder_record_audiocontext.html]
 skip-if = android_version == '17' # android(bug 1232305)
diff --git a/dom/media/test/test_eme_detach_reattach_same_mediakeys_during_playback.html b/dom/media/test/test_eme_detach_reattach_same_mediakeys_during_playback.html
deleted file mode 100644
index 89b14d96ff02..000000000000
--- a/dom/media/test/test_eme_detach_reattach_same_mediakeys_during_playback.html
+++ /dev/null
@@ -1,144 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<head>
-  <title>Test Encrypted Media Extensions</title>
-  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
-  <script type="text/javascript" src="manifest.js"></script>
-  <script type="text/javascript" src="http://test1.mochi.test:8888/tests/dom/media/test/eme.js"></script>
-</head>
-<body>
-<pre id="test">
-<video id="v" controls></video>
-<script class="testbody" type="text/javascript">
-var manager = new MediaTestManager;
-
-var EMEmanifest = [
-  {
-    name:"bipbop 10s",
-    tracks: [
-      {
-          name:"video",
-          type:"video/mp4; codecs=\"avc1.4d4015\"",
-          fragments:[ "bipbop-cenc-video-10s.mp4",
-                    ]
-      }
-    ],
-    keys: {
-      "7e571d037e571d037e571d037e571d11" : "7e5733337e5733337e5733337e573311",
-    },
-    sessionType:"temporary",
-    sessionCount:1,
-    duration:10.01
-  },
-];
-
-function sleep(time) {
-  return new Promise((resolve) => setTimeout(resolve, time));
-}
-
-// To check if playback can be blocked and resumed correctly after
-// detaching original mediakeys and reattach it back.
-function startTest(test, token)
-{
-  manager.started(token);
-
-  var mk_ori;
-  let finish = new EMEPromise;
-
-  let v = document.getElementById("v");
-  let sessions = [];
-  function onSessionCreated(session) {
-    sessions.push(session);
-  }
-
-  function closeSessions() {
-    let p = new EMEPromise;
-    Promise.all(sessions.map(s => s.close()))
-    .then(p.resolve, p.reject);
-    return p.promise;
-  }
-
-  function setMediaKeysToElement(mk, solve, reject) {
-    v.setMediaKeys(mk).then(solve, reject);
-  }
-
-  function ReattachOriMediaKeys() {
-    function onOriMediaKeysSetOK() {
-      ok(true, TimeStamp(token) + " (ENCRYPTED) Set original MediaKeys back OK!");
-    }
-    function onOriMediaKeysSetFailed() {
-      ok(false, " Failed to set original mediakeys back.");
-    }
-
-    function onCanPlayAgain(ev) {
-      Promise.all([closeSessions()])
-      .then(() => {
-        ok(true, " (ENCRYPTED) Playback can be resumed.");
-        manager.finished(token);
-      }, () => {
-        ok(false, TimeStamp(token) + " Sessions are closed incorrectly.");
-        manager.finished(token);
-      });
-    }
-
-    once(v, "canplay", onCanPlayAgain);
-    setMediaKeysToElement(mk_ori, onOriMediaKeysSetOK, onOriMediaKeysSetFailed)
-  }
-
-  function triggerSeek() {
-    v.currentTime = v.duration / 2;
-  }
-
-  function onCanPlay(ev) {
-    function onSetMediaKeysToNullOK() {
-      ok(true, TimeStamp(token) + " Set MediaKeys to null. OK!");
-
-      triggerSeek();
-
-      SimpleTest.requestFlakyTimeout("To reattach mediakeys back again in 5s.");
-      sleep(5000).then(ReattachOriMediaKeys);
-    }
-    function onSetMediaKeysToNullFailed() {
-      ok(false, TimeStamp(token) + " Set MediaKeys to null. FAILED!");
-    }
-
-    SimpleTest.requestFlakyTimeout("To detach mediakeys after receiving 'canplay' event in 2s");
-    sleep(2000).then(() => {
-      setMediaKeysToElement(null, onSetMediaKeysToNullOK, onSetMediaKeysToNullFailed);
-    });
-  }
-
-  once(v, "canplay", onCanPlay);
-
-  var p1 = LoadInitData(v, test, token);
-  var p2 = CreateAndSetMediaKeys(v, test, token);
-  var p3 = LoadTest(test, v, token);
-  Promise.all([p1, p2, p3])
-  .then(values => {
-    let initData = values[0];
-    // stash the mediakeys
-    mk_ori = v.mediaKeys;
-    initData.map(ev => {
-      let session = v.mediaKeys.createSession();
-      onSessionCreated(session);
-      MakeRequest(test, token, ev, session);
-    });
-  })
-  .then(() => {
-    return finish.promise;
-  })
-  .catch(reason => ok(false, reason))
-}
-
-function beginTest() {
-  manager.runTests(EMEmanifest, startTest);
-}
-
-SimpleTest.waitForExplicitFinish();
-SetupEMEPref(beginTest);
-
-</script>
-</pre>
-</body>
-</html>
diff --git a/dom/media/test/test_eme_unsetMediaKeys_then_capture.html b/dom/media/test/test_eme_unsetMediaKeys_then_capture.html
deleted file mode 100644
index 1cb1614f311b..000000000000
--- a/dom/media/test/test_eme_unsetMediaKeys_then_capture.html
+++ /dev/null
@@ -1,117 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<head>
-  <title>Test Encrypted Media Extensions</title>
-  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
-  <script type="text/javascript" src="manifest.js"></script>
-  <script type="text/javascript" src="http://test1.mochi.test:8888/tests/dom/media/test/eme.js"></script>
-</head>
-<body>
-<pre id="test">
-<script class="testbody" type="text/javascript">
-var manager = new MediaTestManager;
-
-// Test that if we can capture a video frame while playing clear content after
-// removing the MediaKeys object which was used for a previous encrypted content
-// playback on the same video element
-function startTest(test, token)
-{
-  manager.started(token);
-  var sessions = [];
-  function onSessionCreated(session) {
-    sessions.push(session);
-  }
-
-  function closeSessions() {
-    let p = new EMEPromise;
-    Promise.all(sessions.map(s => s.close()))
-    .then(p.resolve, p.reject);
-    return p.promise;
-  }
-
-  let v = document.createElement("video");
-  document.body.appendChild(v);
-
-  let finish = new EMEPromise;
-
-  function onVideoEnded(ev) {
-    ok(true, TimeStamp(token) + " (ENCRYPTED) content playback ended.");
-    v.removeEventListener("ended", onVideoEnded);
-
-    function playClearVideo() {
-      var p1 = once(v, 'ended', (e) => {
-        ok(true, TimeStamp(token) + " (CLEAR) content playback ended.");
-        console.log(" bipbop.mp4 playback ended !!");
-      });
-      var p2 = once(v, 'loadeddata', (e) => {
-        ok(true, TimeStamp(token) + " Receiving event 'loadeddata' for (CLEAR) content.");
-        canvasElem = document.createElement('canvas');
-        document.body.appendChild(canvasElem);
-        ctx2d = canvasElem.getContext('2d');
-
-        var gotTypeError = false;
-        try {
-          ctx2d.drawImage(v, 0, 0);
-        } catch (e) {
-          if (e instanceof TypeError) {
-            gotTypeError = true;
-          }
-        }
-        ok(!gotTypeError, TimeStamp(token) + " Canvas2D context drawImage succeed.")
-      });
-      v.src = 'bipbop_225w_175kbps.mp4';
-      v.play();
-      Promise.all([p1, p2, closeSessions()]).then(() => {
-        manager.finished(token);
-      }, () => {
-        ok(false, TimeStamp(token) + " Something wrong.");
-        manager.finished(token);
-      });
-    }
-
-    Promise.all(sessions.map(s => s.close()))
-    .then(() => {
-      v.setMediaKeys(null)
-      .then(() => {
-        ok(true, TimeStamp(token) + " Setting MediaKeys to null.");
-        playClearVideo();
-      }, () => {
-        ok(false, TimeStamp(token) + " Setting MediaKeys to null.");
-      });;
-    });
-  }
-
-  v.addEventListener("ended", onVideoEnded);
-
-  // Create a MediaKeys object and set to HTMLMediaElement then start the playback.
-  Promise.all([
-    LoadInitData(v, test, token),
-    CreateAndSetMediaKeys(v, test, token),
-    LoadTest(test, v, token)])
-  .then(values => {
-    let initData = values[0];
-    v.play();
-    initData.map(ev => {
-      let session = v.mediaKeys.createSession();
-      onSessionCreated(session);
-      MakeRequest(test, token, ev, session);
-    });
-  })
-  .then(() => {
-    return finish.promise;
-  })
-  .catch(reason => ok(false, reason))
-}
-
-function beginTest() {
-  manager.runTests(gEMETests, startTest);
-}
-
-SimpleTest.waitForExplicitFinish();
-SetupEMEPref(beginTest);
-
-</script>
-</pre>
-</body>
-</html>
diff --git a/gfx/layers/SyncObject.h b/gfx/layers/SyncObject.h
index e7c454570a72..874b30f75445 100644
--- a/gfx/layers/SyncObject.h
+++ b/gfx/layers/SyncObject.h
@@ -28,14 +28,15 @@ public:
 
   static already_AddRefed<SyncObjectHost> CreateSyncObjectHost(
 #ifdef XP_WIN
-                                                                       ID3D11Device* aDevice = nullptr
+                                                               ID3D11Device* aDevice = nullptr
 #endif
-                                                                      );
+                                                              );
 
   virtual bool Init() = 0;
 
   virtual SyncHandle GetSyncHandle() = 0;
 
+  // Return false for failed synchronization.
   virtual bool Synchronize() = 0;
 
 protected:
@@ -50,9 +51,9 @@ public:
 
   static already_AddRefed<SyncObjectClient> CreateSyncObjectClient(SyncHandle aHandle
 #ifdef XP_WIN
-                                                                     , ID3D11Device* aDevice = nullptr
+                                                                   , ID3D11Device* aDevice = nullptr
 #endif
-                                                                    );
+                                                                  );
 
   enum class SyncType {
     D3D11,
@@ -60,7 +61,8 @@ public:
 
   virtual SyncType GetSyncType() = 0;
 
-  virtual void Synchronize() = 0;
+  // Return false for failed synchronization.
+  virtual bool Synchronize(bool aFallible = false) = 0;
 
   virtual bool IsSyncObjectValid() = 0;
 
diff --git a/gfx/layers/d3d11/TextureD3D11.cpp b/gfx/layers/d3d11/TextureD3D11.cpp
index ad95eeeb1104..407f589723e5 100644
--- a/gfx/layers/d3d11/TextureD3D11.cpp
+++ b/gfx/layers/d3d11/TextureD3D11.cpp
@@ -1697,7 +1697,7 @@ SyncObjectD3D11Client::SyncObjectD3D11Client(SyncHandle aSyncHandle, ID3D11Devic
 }
 
 bool
-SyncObjectD3D11Client::Init()
+SyncObjectD3D11Client::Init(bool aFallible)
 {
   if (mKeyedMutex) {
     return true;
@@ -1709,7 +1709,7 @@ SyncObjectD3D11Client::Init()
     (void**)(ID3D11Texture2D**)getter_AddRefs(mSyncTexture));
   if (FAILED(hr) || !mSyncTexture) {
     gfxCriticalNote << "Failed to OpenSharedResource for SyncObjectD3D11: " << hexa(hr);
-    if (ShouldDevCrashOnSyncInitFailure()) {
+    if (!aFallible && ShouldDevCrashOnSyncInitFailure()) {
       gfxDevCrash(LogReason::D3D11FinalizeFrame) << "Without device reset: " << hexa(hr);
     }
     return false;
@@ -1719,8 +1719,13 @@ SyncObjectD3D11Client::Init()
   if (FAILED(hr) || !mKeyedMutex) {
     // Leave both the critical error and MOZ_CRASH for now; the critical error lets
     // us "save" the hr value.  We will probably eventually replace this with gfxDevCrash.
-    gfxCriticalError() << "Failed to get KeyedMutex (2): " << hexa(hr);
-    MOZ_CRASH("GFX: Cannot get D3D11 KeyedMutex");
+    if (!aFallible) {
+      gfxCriticalError() << "Failed to get KeyedMutex (2): " << hexa(hr);
+      MOZ_CRASH("GFX: Cannot get D3D11 KeyedMutex");
+    } else {
+      gfxCriticalNote << "Failed to get KeyedMutex (3): " << hexa(hr);
+    }
+    return false;
   }
 
   return true;
@@ -1747,8 +1752,8 @@ SyncObjectD3D11Client::IsSyncObjectValid()
 // into our sync object and only use a lock for this sync object.
 // This way, we don't have to sync every texture we send to the compositor.
 // We only have to do this once per transaction.
-void
-SyncObjectD3D11Client::Synchronize()
+bool
+SyncObjectD3D11Client::Synchronize(bool aFallible)
 {
   // Since this can be called from either the Paint or Main thread.
   // We don't want this to race since we initialize the sync texture here
@@ -1756,10 +1761,10 @@ SyncObjectD3D11Client::Synchronize()
   MutexAutoLock syncLock(mSyncLock);
 
   if (!mSyncedTextures.size()) {
-    return;
+    return true;
   }
-  if (!Init()) {
-    return;
+  if (!Init(aFallible)) {
+    return false;
   }
 
   HRESULT hr;
@@ -1768,9 +1773,14 @@ SyncObjectD3D11Client::Synchronize()
   if (hr == WAIT_TIMEOUT) {
     if (DeviceManagerDx::Get()->HasDeviceReset()) {
       gfxWarning() << "AcquireSync timed out because of device reset.";
-      return;
+      return false;
     }
-    gfxDevCrash(LogReason::D3D11SyncLock) << "Timeout on the D3D11 sync lock";
+    if (aFallible) {
+      gfxWarning() << "Timeout on the D3D11 sync lock.";
+    } else {
+      gfxDevCrash(LogReason::D3D11SyncLock) << "Timeout on the D3D11 sync lock.";
+    }
+    return false;
   }
 
   D3D11_BOX box;
@@ -1782,13 +1792,13 @@ SyncObjectD3D11Client::Synchronize()
 
   if (dev == DeviceManagerDx::Get()->GetContentDevice()) {
     if (DeviceManagerDx::Get()->HasDeviceReset()) {
-      return;
+      return false;
     }
   }
 
   if (dev != mDevice) {
     gfxWarning() << "Attempt to sync texture from invalid device.";
-    return;
+    return false;
   }
 
   RefPtr<ID3D11DeviceContext> ctx;
@@ -1799,6 +1809,8 @@ SyncObjectD3D11Client::Synchronize()
   }
 
   mSyncedTextures.clear();
+
+  return true;
 }
 
 uint32_t
diff --git a/gfx/layers/d3d11/TextureD3D11.h b/gfx/layers/d3d11/TextureD3D11.h
index 035e52fdc0d8..2858268ec833 100644
--- a/gfx/layers/d3d11/TextureD3D11.h
+++ b/gfx/layers/d3d11/TextureD3D11.h
@@ -478,7 +478,7 @@ class SyncObjectD3D11Client : public SyncObjectClient
 public:
   explicit SyncObjectD3D11Client(SyncHandle aSyncHandle, ID3D11Device* aDevice);
 
-  virtual void Synchronize() override;
+  virtual bool Synchronize(bool aFallible) override;
 
   virtual bool IsSyncObjectValid() override;
 
@@ -487,7 +487,7 @@ public:
   void RegisterTexture(ID3D11Texture2D* aTexture);
 
 private:
-  bool Init();
+  bool Init(bool aFallible);
 
   SyncHandle mSyncHandle;
   RefPtr<ID3D11Device> mDevice;
diff --git a/js/src/gc/GCRuntime.h b/js/src/gc/GCRuntime.h
index 4d19f5269228..e9f404f84e11 100644
--- a/js/src/gc/GCRuntime.h
+++ b/js/src/gc/GCRuntime.h
@@ -1210,10 +1210,11 @@ class GCRuntime
     AtomMarkingRuntime atomMarking;
 
   private:
-    // When empty, chunks reside in the emptyChunks pool and are re-used as
-    // needed or eventually expired if not re-used. The emptyChunks pool gets
-    // refilled from the background allocation task heuristically so that empty
-    // chunks should always available for immediate allocation without syscalls.
+    // When chunks are empty, they reside in the emptyChunks pool and are
+    // re-used as needed or eventually expired if not re-used. The emptyChunks
+    // pool gets refilled from the background allocation task heuristically so
+    // that empty chunks should always be available for immediate allocation
+    // without syscalls.
     GCLockData<ChunkPool> emptyChunks_;
 
     // Chunks which have had some, but not all, of their arenas allocated live
diff --git a/js/src/gc/Nursery.cpp b/js/src/gc/Nursery.cpp
index 1ea06efde9b1..6132c8accb68 100644
--- a/js/src/gc/Nursery.cpp
+++ b/js/src/gc/Nursery.cpp
@@ -116,7 +116,8 @@ js::Nursery::Nursery(JSRuntime* rt)
   , currentStartPosition_(0)
   , currentEnd_(0)
   , currentChunk_(0)
-  , maxNurseryChunks_(0)
+  , maxChunkCount_(0)
+  , chunkCountLimit_(0)
   , previousPromotionRate_(0)
   , profileThreshold_(0)
   , enableProfiling_(false)
@@ -140,15 +141,18 @@ js::Nursery::init(uint32_t maxNurseryBytes, AutoLockGCBgAlloc& lock)
         return false;
 
     /* maxNurseryBytes parameter is rounded down to a multiple of chunk size. */
-    maxNurseryChunks_ = maxNurseryBytes >> ChunkShift;
+    chunkCountLimit_ = maxNurseryBytes >> ChunkShift;
 
     /* If no chunks are specified then the nursery is permanently disabled. */
-    if (maxNurseryChunks_ == 0)
+    if (chunkCountLimit_ == 0)
         return true;
 
-    updateNumChunksLocked(1, lock);
-    if (numChunks() == 0)
+    maxChunkCount_ = 1;
+    if (!allocateNextChunk(0, lock)) {
+        maxChunkCount_ = 0;
         return false;
+    }
+    /* After this point the Nursery has been enabled */
 
     setCurrentChunk(0);
     setStartPosition();
@@ -192,12 +196,17 @@ js::Nursery::enable()
 {
     MOZ_ASSERT(isEmpty());
     MOZ_ASSERT(!runtime()->gc.isVerifyPreBarriersEnabled());
-    if (isEnabled() || !maxChunks())
+    if (isEnabled() || !chunkCountLimit())
         return;
 
-    updateNumChunks(1);
-    if (numChunks() == 0)
-        return;
+    {
+        AutoLockGCBgAlloc lock(runtime());
+        maxChunkCount_ = 1;
+        if (!allocateNextChunk(0, lock)) {
+            maxChunkCount_ = 0;
+            return;
+        }
+    }
 
     setCurrentChunk(0);
     setStartPosition();
@@ -215,8 +224,12 @@ js::Nursery::disable()
     MOZ_ASSERT(isEmpty());
     if (!isEnabled())
         return;
-    updateNumChunks(0);
+
+    freeChunksFrom(0);
+    maxChunkCount_ = 0;
+
     currentEnd_ = 0;
+
     runtime()->gc.storeBuffer().disable();
 }
 
@@ -237,7 +250,7 @@ js::Nursery::isEmpty() const
 void
 js::Nursery::enterZealMode() {
     if (isEnabled())
-        updateNumChunks(maxNurseryChunks_);
+        maxChunkCount_ = chunkCountLimit();
 }
 
 void
@@ -303,9 +316,19 @@ js::Nursery::allocate(size_t size)
 #endif
 
     if (currentEnd() < position() + size) {
-        if (currentChunk_ + 1 == numChunks())
+        unsigned chunkno = currentChunk_ + 1;
+        MOZ_ASSERT(chunkno <= chunkCountLimit());
+        MOZ_ASSERT(chunkno <= maxChunkCount());
+        MOZ_ASSERT(chunkno <= allocatedChunkCount());
+        if (chunkno == maxChunkCount())
             return nullptr;
-        setCurrentChunk(currentChunk_ + 1);
+        if (MOZ_UNLIKELY(chunkno == allocatedChunkCount())) {
+            AutoLockGCBgAlloc lock(runtime());
+            if (!allocateNextChunk(chunkno, lock))
+                return nullptr;
+            MOZ_ASSERT(chunkno < allocatedChunkCount());
+        }
+        setCurrentChunk(chunkno);
     }
 
     void* thing = (void*)position();
@@ -524,6 +547,7 @@ js::Nursery::renderProfileJSON(JSONPrinter& json) const
     json.property("bytes_used", previousGC.nurseryUsedBytes);
     json.property("cur_capacity", previousGC.nurseryCapacity);
     json.property("new_capacity", spaceToEnd());
+    json.property("lazy_capacity", allocatedChunkCount() * ChunkSize);
 
     json.beginObjectProperty("phase_times");
 
@@ -686,7 +710,7 @@ js::Nursery::collect(JS::gcreason::Reason reason)
     // Disable the nursery if the user changed the configuration setting.  The
     // nursery can only be re-enabled by resetting the configurationa and
     // restarting firefox.
-    if (maxNurseryChunks_ == 0)
+    if (chunkCountLimit_ == 0)
         disable();
 
     endProfile(ProfileKey::Total);
@@ -709,7 +733,7 @@ js::Nursery::collect(JS::gcreason::Reason reason)
         fprintf(stderr, "MinorGC: %20s %5.1f%% %4u        ",
                 JS::gcreason::ExplainReason(reason),
                 promotionRate * 100,
-                numChunks());
+                maxChunkCount());
         printProfileDurations(profileDurations_);
 
         if (reportTenurings_) {
@@ -914,18 +938,18 @@ js::Nursery::clear()
 {
 #ifdef JS_GC_ZEAL
     /* Poison the nursery contents so touching a freed object will crash. */
-    for (unsigned i = 0; i < numChunks(); i++)
+    for (unsigned i = 0; i < allocatedChunkCount(); i++)
         chunk(i).poisonAndInit(runtime(), JS_SWEPT_NURSERY_PATTERN);
 
     if (runtime()->hasZealMode(ZealMode::GenerationalGC)) {
         /* Only reset the alloc point when we are close to the end. */
-        if (currentChunk_ + 1 == numChunks())
+        if (currentChunk_ + 1 == maxChunkCount())
             setCurrentChunk(0);
     } else
 #endif
     {
 #ifdef JS_CRASH_DIAGNOSTICS
-        for (unsigned i = 0; i < numChunks(); ++i)
+        for (unsigned i = 0; i < allocatedChunkCount(); ++i)
             chunk(i).poisonAndInit(runtime(), JS_SWEPT_NURSERY_PATTERN);
 #endif
         setCurrentChunk(0);
@@ -938,7 +962,7 @@ js::Nursery::clear()
 size_t
 js::Nursery::spaceToEnd() const
 {
-    unsigned lastChunk = numChunks() - 1;
+    unsigned lastChunk = maxChunkCount() - 1;
 
     MOZ_ASSERT(lastChunk >= currentStartChunk_);
     MOZ_ASSERT(currentStartPosition_ - chunk(currentStartChunk_).start() <= NurseryChunkUsableSize);
@@ -946,7 +970,7 @@ js::Nursery::spaceToEnd() const
     size_t bytes = (chunk(currentStartChunk_).end() - currentStartPosition_) +
                    ((lastChunk - currentStartChunk_) * NurseryChunkUsableSize);
 
-    MOZ_ASSERT(bytes <= numChunks() * NurseryChunkUsableSize);
+    MOZ_ASSERT(bytes <= maxChunkCount() * NurseryChunkUsableSize);
 
     return bytes;
 }
@@ -954,14 +978,40 @@ js::Nursery::spaceToEnd() const
 MOZ_ALWAYS_INLINE void
 js::Nursery::setCurrentChunk(unsigned chunkno)
 {
-    MOZ_ASSERT(chunkno < maxChunks());
-    MOZ_ASSERT(chunkno < numChunks());
+    MOZ_ASSERT(chunkno < chunkCountLimit());
+    MOZ_ASSERT(chunkno < allocatedChunkCount());
     currentChunk_ = chunkno;
     position_ = chunk(chunkno).start();
     currentEnd_ = chunk(chunkno).end();
     chunk(chunkno).poisonAndInit(runtime(), JS_FRESH_NURSERY_PATTERN);
 }
 
+bool
+js::Nursery::allocateNextChunk(const unsigned chunkno,
+    AutoLockGCBgAlloc& lock)
+{
+    const unsigned priorCount = allocatedChunkCount();
+    const unsigned newCount = priorCount + 1;
+
+    MOZ_ASSERT((chunkno == currentChunk_ + 1) || (chunkno == 0 && allocatedChunkCount() == 0));
+    MOZ_ASSERT(chunkno == allocatedChunkCount());
+    MOZ_ASSERT(chunkno < chunkCountLimit());
+    MOZ_ASSERT(chunkno < maxChunkCount());
+
+    if (!chunks_.resize(newCount))
+        return false;
+
+    Chunk* newChunk;
+    newChunk = runtime()->gc.getOrAllocChunk(lock);
+    if (!newChunk) {
+        chunks_.shrinkTo(priorCount);
+        return false;
+    }
+
+    chunks_[chunkno] = NurseryChunk::fromChunk(newChunk);
+    return true;
+}
+
 MOZ_ALWAYS_INLINE void
 js::Nursery::setStartPosition()
 {
@@ -998,23 +1048,25 @@ js::Nursery::maybeResizeNursery(JS::gcreason::Reason reason)
         float(previousGC.tenuredBytes) / float(previousGC.nurseryCapacity);
 
     newMaxNurseryChunks = runtime()->gc.tunables.gcMaxNurseryBytes() >> ChunkShift;
-    if (newMaxNurseryChunks != maxNurseryChunks_) {
-        maxNurseryChunks_ = newMaxNurseryChunks;
+    if (newMaxNurseryChunks != chunkCountLimit_) {
+        chunkCountLimit_ = newMaxNurseryChunks;
         /* The configured maximum nursery size is changing */
-        const int extraChunks = numChunks() - newMaxNurseryChunks;
-        if (extraChunks > 0) {
+        if (maxChunkCount() > newMaxNurseryChunks) {
             /* We need to shrink the nursery */
-            shrinkAllocableSpace(extraChunks);
+            shrinkAllocableSpace(newMaxNurseryChunks);
 
             previousPromotionRate_ = promotionRate;
             return;
         }
     }
 
-    if (promotionRate > GrowThreshold)
+    if (promotionRate > GrowThreshold) {
+        // The GC nursery is an optimization and so if we fail to allocate
+        // nursery chunks we do not report an error.
         growAllocableSpace();
-    else if (promotionRate < ShrinkThreshold && previousPromotionRate_ < ShrinkThreshold)
-        shrinkAllocableSpace(1);
+    } else if (promotionRate < ShrinkThreshold && previousPromotionRate_ < ShrinkThreshold) {
+        shrinkAllocableSpace(maxChunkCount() - 1);
+    }
 
     previousPromotionRate_ = promotionRate;
 }
@@ -1022,72 +1074,46 @@ js::Nursery::maybeResizeNursery(JS::gcreason::Reason reason)
 void
 js::Nursery::growAllocableSpace()
 {
-    updateNumChunks(Min(numChunks() * 2, maxNurseryChunks_));
+    maxChunkCount_ = Min(maxChunkCount() * 2, chunkCountLimit());
 }
 
 void
-js::Nursery::shrinkAllocableSpace(unsigned removeNumChunks)
+js::Nursery::freeChunksFrom(unsigned firstFreeChunk)
+{
+    MOZ_ASSERT(firstFreeChunk < chunks_.length());
+    {
+        AutoLockGC lock(runtime());
+        for (unsigned i = firstFreeChunk; i < chunks_.length(); i++)
+            runtime()->gc.recycleChunk(chunk(i).toChunk(runtime()), lock);
+    }
+    chunks_.shrinkTo(firstFreeChunk);
+}
+
+void
+js::Nursery::shrinkAllocableSpace(unsigned newCount)
 {
 #ifdef JS_GC_ZEAL
     if (runtime()->hasZealMode(ZealMode::GenerationalGC))
         return;
 #endif
-    updateNumChunks(Max(numChunks() - removeNumChunks, 1u));
+
+    // Don't shrink the nursery to zero (use Nursery::disable() instead) and
+    // don't attempt to shrink it to the same size.
+    if ((newCount == 0) || (newCount == maxChunkCount()))
+        return;
+
+    MOZ_ASSERT(newCount < maxChunkCount());
+
+    if (newCount < allocatedChunkCount())
+        freeChunksFrom(newCount);
+
+    maxChunkCount_ = newCount;
 }
 
 void
 js::Nursery::minimizeAllocableSpace()
 {
-#ifdef JS_GC_ZEAL
-    if (runtime()->hasZealMode(ZealMode::GenerationalGC))
-        return;
-#endif
-    updateNumChunks(1);
-}
-
-void
-js::Nursery::updateNumChunks(unsigned newCount)
-{
-    if (numChunks() != newCount) {
-        AutoLockGCBgAlloc lock(runtime());
-        updateNumChunksLocked(newCount, lock);
-    }
-}
-
-void
-js::Nursery::updateNumChunksLocked(unsigned newCount,
-                                   AutoLockGCBgAlloc& lock)
-{
-    // The GC nursery is an optimization and so if we fail to allocate nursery
-    // chunks we do not report an error.
-
-    MOZ_ASSERT(newCount <= maxChunks());
-
-    unsigned priorCount = numChunks();
-    MOZ_ASSERT(priorCount != newCount);
-
-    if (newCount < priorCount) {
-        // Shrink the nursery and free unused chunks.
-        for (unsigned i = newCount; i < priorCount; i++)
-            runtime()->gc.recycleChunk(chunk(i).toChunk(runtime()), lock);
-        chunks_.shrinkTo(newCount);
-        return;
-    }
-
-    // Grow the nursery and allocate new chunks.
-    if (!chunks_.resize(newCount))
-        return;
-
-    for (unsigned i = priorCount; i < newCount; i++) {
-        auto newChunk = runtime()->gc.getOrAllocChunk(lock);
-        if (!newChunk) {
-            chunks_.shrinkTo(i);
-            return;
-        }
-
-        chunks_[i] = NurseryChunk::fromChunk(newChunk);
-        chunk(i).poisonAndInit(runtime(), JS_FRESH_NURSERY_PATTERN);
-    }
+    shrinkAllocableSpace(1);
 }
 
 bool
diff --git a/js/src/gc/Nursery.h b/js/src/gc/Nursery.h
index 0af23e62254d..d52d60e8628f 100644
--- a/js/src/gc/Nursery.h
+++ b/js/src/gc/Nursery.h
@@ -141,15 +141,22 @@ class Nursery
 
     MOZ_MUST_USE bool init(uint32_t maxNurseryBytes, AutoLockGCBgAlloc& lock);
 
-    unsigned maxChunks() const { return maxNurseryChunks_; }
-    unsigned numChunks() const { return chunks_.length(); }
+    unsigned chunkCountLimit() const { return chunkCountLimit_; }
 
-    bool exists() const { return maxChunks() != 0; }
-    size_t nurserySize() const { return maxChunks() << ChunkShift; }
+    // Number of allocated (ready to use) chunks.
+    unsigned allocatedChunkCount() const { return chunks_.length(); }
+
+    // Total number of chunks and the capacity of the nursery. Chunks will be
+    // lazilly allocated and added to the chunks array up to this limit, after
+    // that the nursery must be collected, this limit may be raised during
+    // collection.
+    unsigned maxChunkCount() const { return maxChunkCount_; }
+
+    bool exists() const { return chunkCountLimit() != 0; }
 
     void enable();
     void disable();
-    bool isEnabled() const { return numChunks() != 0; }
+    bool isEnabled() const { return maxChunkCount() != 0; }
 
     /* Return true if no allocations have been made since the last collection. */
     bool isEmpty() const;
@@ -234,7 +241,7 @@ class Nursery
     MOZ_MUST_USE bool queueDictionaryModeObjectToSweep(NativeObject* obj);
 
     size_t sizeOfHeapCommitted() const {
-        return numChunks() * gc::ChunkSize;
+        return allocatedChunkCount() * gc::ChunkSize;
     }
     size_t sizeOfMallocedBuffers(mozilla::MallocSizeOf mallocSizeOf) const {
         if (!mallocedBuffers.initialized())
@@ -253,7 +260,7 @@ class Nursery
     MOZ_ALWAYS_INLINE size_t freeSpace() const {
         MOZ_ASSERT(currentEnd_ - position_ <= NurseryChunkUsableSize);
         return (currentEnd_ - position_) +
-               (numChunks() - currentChunk_ - 1) * NurseryChunkUsableSize;
+               (maxChunkCount() - currentChunk_ - 1) * NurseryChunkUsableSize;
     }
 
 #ifdef JS_GC_ZEAL
@@ -311,8 +318,18 @@ class Nursery
     /* The index of the chunk that is currently being allocated from. */
     unsigned currentChunk_;
 
-    /* Maximum number of chunks to allocate for the nursery. */
-    unsigned maxNurseryChunks_;
+    /*
+     * The nursery may grow the chunks_ vector up to this size without a
+     * collection.  This allows the nursery to grow lazilly.  This limit may
+     * change during maybeResizeNursery() each collection.
+     */
+    unsigned maxChunkCount_;
+
+    /*
+     * This limit is fixed by configuration.  It represents the maximum size
+     * the nursery is permitted to tune itself to in maybeResizeNursery();
+     */
+    unsigned chunkCountLimit_;
 
     /* Promotion rate for the previous minor collection. */
     float previousPromotionRate_;
@@ -419,8 +436,6 @@ class Nursery
     Canary* lastCanary_;
 #endif
 
-    NurseryChunk* allocChunk();
-
     NurseryChunk& chunk(unsigned index) const {
         return *chunks_[index];
     }
@@ -428,9 +443,12 @@ class Nursery
     void setCurrentChunk(unsigned chunkno);
     void setStartPosition();
 
-    void updateNumChunks(unsigned newCount);
-    void updateNumChunksLocked(unsigned newCount,
-                               AutoLockGCBgAlloc& lock);
+    /*
+     * Allocate the next chunk, or the first chunk for initialization.
+     * Callers will probably want to call setCurrentChunk(0) next.
+     */
+    MOZ_MUST_USE bool allocateNextChunk(unsigned chunkno,
+        AutoLockGCBgAlloc& lock);
 
     MOZ_ALWAYS_INLINE uintptr_t currentEnd() const;
 
@@ -483,9 +501,13 @@ class Nursery
     /* Change the allocable space provided by the nursery. */
     void maybeResizeNursery(JS::gcreason::Reason reason);
     void growAllocableSpace();
-    void shrinkAllocableSpace(unsigned removeNumChunks);
+    void shrinkAllocableSpace(unsigned newCount);
     void minimizeAllocableSpace();
 
+    // Free the chunks starting at firstFreeChunk until the end of the chunks
+    // vector. Shrinks the vector but does not update maxChunkCount().
+    void freeChunksFrom(unsigned firstFreeChunk);
+
     /* Profile recording and printing. */
     void maybeClearProfileDurations();
     void startProfile(ProfileKey key);
diff --git a/mobile/android/config/mozconfigs/android-aarch64/l10n-nightly b/mobile/android/config/mozconfigs/android-aarch64/l10n-nightly
index 0d2c0b4b7527..35d9ca226329 100644
--- a/mobile/android/config/mozconfigs/android-aarch64/l10n-nightly
+++ b/mobile/android/config/mozconfigs/android-aarch64/l10n-nightly
@@ -2,21 +2,39 @@ NO_NDK=1
 
 . "$topsrcdir/mobile/android/config/mozconfigs/common"
 
-. "$topsrcdir/mobile/android/config/mozconfigs/android-aarch64/nightly"
-
 # L10n
 ac_add_options --with-l10n-base=../../l10n-central
 
-# Don't autoclobber l10n, as this can lead to missing binaries and broken builds
-# Bug 1283438
-mk_add_options AUTOCLOBBER=
-
 . "$topsrcdir/build/mozconfig.no-compile"
 
 # Global options
 ac_add_options --disable-tests
 
+# Android
+ac_add_options --with-android-min-sdk=21
+ac_add_options --target=aarch64-linux-android
+
 ac_add_options --enable-updater
 ac_add_options --enable-update-channel=${MOZ_UPDATE_CHANNEL}
 
+export MOZILLA_OFFICIAL=1
+
+ac_add_options --with-branding=mobile/android/branding/nightly
+
+ac_add_options --disable-stdcxx-compat
+
+# Don't autoclobber l10n, as this can lead to missing binaries and broken builds
+# Bug 1283438
+mk_add_options AUTOCLOBBER=
+
+# Disable Keyfile Loading (and checks) since l10n doesn't need these keys
+# This overrides the settings in the common android mozconfig
+ac_add_options --without-mozilla-api-keyfile
+ac_add_options --without-google-api-keyfile
+ac_add_options --without-adjust-sdk-keyfile
+ac_add_options --without-leanplum-sdk-keyfile
+ac_add_options --without-pocket-api-keyfile
+# Similarly explicitly disable install tracking for l10n, we'll inherit from en-US
+export MOZ_INSTALL_TRACKING=
+
 . "$topsrcdir/mobile/android/config/mozconfigs/common.override"
diff --git a/mobile/android/config/mozconfigs/android-api-16/l10n-nightly b/mobile/android/config/mozconfigs/android-api-16/l10n-nightly
index bdd0bb41acfa..4144dfa19daf 100644
--- a/mobile/android/config/mozconfigs/android-api-16/l10n-nightly
+++ b/mobile/android/config/mozconfigs/android-api-16/l10n-nightly
@@ -2,21 +2,44 @@ NO_NDK=1
 
 . "$topsrcdir/mobile/android/config/mozconfigs/common"
 
-. "$topsrcdir/mobile/android/config/mozconfigs/android-api-16/nightly"
-
 # L10n
 ac_add_options --with-l10n-base=../../l10n-central
 
-# Don't autoclobber l10n, as this can lead to missing binaries and broken builds
-# Bug 1283438
-mk_add_options AUTOCLOBBER=
-
 . "$topsrcdir/build/mozconfig.no-compile"
 
 # Global options
 ac_add_options --disable-tests
 
+# Android
+# Warning: Before increasing the with-android-min-sdk value, please note several places in and out
+# of tree have to be changed. Otherwise, places like Treeherder or archive.mozilla.org will
+# advertise a bad API level. This may confuse people. As an example, please look at bug 1384482.
+# If you think you can't handle the whole set of changes, please reach out to the Release
+# Engineering team.
+ac_add_options --with-android-min-sdk=16
+ac_add_options --target=arm-linux-androideabi
+
 ac_add_options --enable-updater
 ac_add_options --enable-update-channel=${MOZ_UPDATE_CHANNEL}
 
+export MOZILLA_OFFICIAL=1
+
+ac_add_options --with-branding=mobile/android/branding/nightly
+
+ac_add_options --disable-stdcxx-compat
+
+# Don't autoclobber l10n, as this can lead to missing binaries and broken builds
+# Bug 1283438
+mk_add_options AUTOCLOBBER=
+
+# Disable Keyfile Loading (and checks) since l10n doesn't need these keys
+# This overrides the settings in the common android mozconfig
+ac_add_options --without-mozilla-api-keyfile
+ac_add_options --without-google-api-keyfile
+ac_add_options --without-adjust-sdk-keyfile
+ac_add_options --without-leanplum-sdk-keyfile
+ac_add_options --without-pocket-api-keyfile
+# Similarly explicitly disable install tracking for l10n, we'll inherit from en-US
+export MOZ_INSTALL_TRACKING=
+
 . "$topsrcdir/mobile/android/config/mozconfigs/common.override"
diff --git a/mobile/android/config/mozconfigs/android-x86/l10n-nightly b/mobile/android/config/mozconfigs/android-x86/l10n-nightly
index c4cac7ceb010..118d3407ceca 100644
--- a/mobile/android/config/mozconfigs/android-x86/l10n-nightly
+++ b/mobile/android/config/mozconfigs/android-x86/l10n-nightly
@@ -2,21 +2,34 @@ NO_NDK=1
 
 . "$topsrcdir/mobile/android/config/mozconfigs/common"
 
-. "$topsrcdir/mobile/android/config/mozconfigs/android-x86/nightly"
-
 # L10n
 ac_add_options --with-l10n-base=../../l10n-central
 
-# Don't autoclobber l10n, as this can lead to missing binaries and broken builds
-# Bug 1283438
-mk_add_options AUTOCLOBBER=
-
 . "$topsrcdir/build/mozconfig.no-compile"
 
 # Global options
 ac_add_options --disable-tests
 
+# Android
+# Warning: Before increasing the with-android-min-sdk value, please note several places in and out
+# of tree have to be changed. Otherwise, places like Treeherder or archive.mozilla.org will
+# advertise a bad API level. This may confuse people. As an example, please look at bug 1384482.
+# If you think you can't handle the whole set of changes, please reach out to the Release
+# Engineering team.
+ac_add_options --target=i386-linux-android
+ac_add_options --with-android-min-sdk=16
+
 ac_add_options --enable-updater
 ac_add_options --enable-update-channel=${MOZ_UPDATE_CHANNEL}
 
+export MOZILLA_OFFICIAL=1
+
+ac_add_options --with-branding=mobile/android/branding/nightly
+
+ac_add_options --disable-stdcxx-compat
+
+# Don't autoclobber l10n, as this can lead to missing binaries and broken builds
+# Bug 1283438
+mk_add_options AUTOCLOBBER=
+
 . "$topsrcdir/mobile/android/config/mozconfigs/common.override"
diff --git a/mobile/android/geckoview/build.gradle b/mobile/android/geckoview/build.gradle
index ee0281423fd4..3a39c41014e0 100644
--- a/mobile/android/geckoview/build.gradle
+++ b/mobile/android/geckoview/build.gradle
@@ -55,8 +55,7 @@ android {
         // TODO: ensure these fields always agree with mobile/android/geckoview/BuildConfig.java.in,
         // either by diffing the processed files or by generating the output from a single source.
         buildConfigField 'String', "GRE_MILESTONE", "\"${mozconfig.substs.GRE_MILESTONE}\""
-        // This should really come from the included binaries, but that's not easy.
-        buildConfigField 'String', "MOZ_APP_ABI", mozconfig.substs['COMPILE_ENVIRONMENT'] ? "\"${ mozconfig.substs.TARGET_XPCOM_ABI}\"" : '"arm-eabi-gcc3"';
+        buildConfigField 'String', "MOZ_APP_ABI", "\"${mozconfig.substs.TARGET_XPCOM_ABI}\"";
         buildConfigField 'String', "MOZ_APP_BASENAME", "\"${mozconfig.substs.MOZ_APP_BASENAME}\"";
 
         // For the benefit of future archaeologists:
diff --git a/mobile/android/gradle/with_gecko_binaries.gradle b/mobile/android/gradle/with_gecko_binaries.gradle
index 9b8bc53074f1..5b067f3d96cc 100644
--- a/mobile/android/gradle/with_gecko_binaries.gradle
+++ b/mobile/android/gradle/with_gecko_binaries.gradle
@@ -152,32 +152,25 @@ ext.configureVariantWithJNIWrappers = { variant, module ->
     // suggest that it is.  It certainly doesn't hurt.
     def prepareDependenciesTask = tasks.getByName("prepare${variant.name.capitalize()}Dependencies")
 
-    def wrapperTask
-    if (System.env.IS_LANGUAGE_REPACK == '1') {
-        // Single-locale l10n repacks set `IS_LANGUAGE_REPACK=1` and don't
-        // really have a build environment.
-        wrapperTask = task("generateJNIWrappersFor${module}${variant.name.capitalize()}")
-    } else {
-        wrapperTask = task("generateJNIWrappersFor${module}${variant.name.capitalize()}", type: JavaExec) {
-            classpath "${topobjdir}/build/annotationProcessors/annotationProcessors.jar"
-    
-            // Configure the classpath at evaluation-time, not at
-            // configuration-time: see above comment.
-            doFirst {
-                classpath variant.javaCompile.classpath
-                // Include android.jar.
-                classpath variant.javaCompile.options.bootClasspath
-            }
-    
-            main = 'org.mozilla.gecko.annotationProcessors.AnnotationProcessor'
-            args module
-            args jarTask.outputs.files.iterator().next()
-    
-            workingDir "${topobjdir}/mobile/android/base"
-    
-            dependsOn jarTask
-            dependsOn prepareDependenciesTask
+    def wrapperTask = task("generateJNIWrappersFor${module}${variant.name.capitalize()}", type: JavaExec) {
+        classpath "${topobjdir}/build/annotationProcessors/annotationProcessors.jar"
+
+        // Configure the classpath at evaluation-time, not at
+        // configuration-time: see above comment.
+        doFirst {
+            classpath variant.javaCompile.classpath
+            // Include android.jar.
+            classpath variant.javaCompile.options.bootClasspath
         }
+
+        main = 'org.mozilla.gecko.annotationProcessors.AnnotationProcessor'
+        args module
+        args jarTask.outputs.files.iterator().next()
+
+        workingDir "${topobjdir}/mobile/android/base"
+
+        dependsOn jarTask
+        dependsOn prepareDependenciesTask
     }
 
     if (module == 'Generated') {
diff --git a/modules/libpref/Preferences.cpp b/modules/libpref/Preferences.cpp
index b203a2722b6a..1c8520d04c10 100644
--- a/modules/libpref/Preferences.cpp
+++ b/modules/libpref/Preferences.cpp
@@ -3263,7 +3263,7 @@ class ValueObserver final
   : public nsIObserver
   , public ValueObserverHashKey
 {
-  ~ValueObserver() { Preferences::RemoveObserver(this, mPrefName.get()); }
+  ~ValueObserver() = default;
 
 public:
   NS_DECL_ISUPPORTS
@@ -4681,8 +4681,7 @@ pref_InitInitialObjects()
 
   if (!strcmp(NS_STRINGIFY(MOZ_UPDATE_CHANNEL), "nightly") ||
       !strcmp(NS_STRINGIFY(MOZ_UPDATE_CHANNEL), "aurora") ||
-      !strcmp(NS_STRINGIFY(MOZ_UPDATE_CHANNEL), "beta") ||
-      developerBuild) {
+      !strcmp(NS_STRINGIFY(MOZ_UPDATE_CHANNEL), "beta") || developerBuild) {
     PREF_SetBoolPref(kTelemetryPref, true, true);
   } else {
     PREF_SetBoolPref(kTelemetryPref, false, true);
@@ -4951,13 +4950,13 @@ NotifyObserver(const char* aPref, void* aClosure)
 }
 
 static void
-RegisterPriorityCallback(PrefChangedFunc aCallback,
-                         const char* aPref,
-                         void* aClosure)
+RegisterCallbackHelper(PrefChangedFunc aCallback,
+                       const char* aPref,
+                       void* aClosure,
+                       Preferences::MatchKind aMatchKind,
+                       bool aIsPriority)
 {
-  MOZ_ASSERT(Preferences::IsServiceAvailable());
-
-  ValueObserverHashKey hashKey(aPref, aCallback, Preferences::ExactMatch);
+  ValueObserverHashKey hashKey(aPref, aCallback, aMatchKind);
   RefPtr<ValueObserver> observer;
   gObserverTable->Get(&hashKey, getter_AddRefs(observer));
   if (observer) {
@@ -4965,15 +4964,27 @@ RegisterPriorityCallback(PrefChangedFunc aCallback,
     return;
   }
 
-  observer = new ValueObserver(aPref, aCallback, Preferences::ExactMatch);
+  observer = new ValueObserver(aPref, aCallback, aMatchKind);
   observer->AppendClosure(aClosure);
-  PREF_RegisterCallback(aPref,
-                        NotifyObserver,
-                        static_cast<nsIObserver*>(observer),
-                        /* isPriority */ true);
+  PREF_RegisterCallback(
+    aPref, NotifyObserver, static_cast<nsIObserver*>(observer), aIsPriority);
   gObserverTable->Put(observer, observer);
 }
 
+// RegisterVarCacheCallback uses high priority callbacks to ensure that cache
+// observers are called prior to ordinary pref observers. Doing this ensures
+// that ordinary observers will never get stale values from cache variables.
+static void
+RegisterVarCacheCallback(PrefChangedFunc aCallback,
+                         const char* aPref,
+                         void* aClosure)
+{
+  MOZ_ASSERT(Preferences::IsServiceAvailable());
+
+  RegisterCallbackHelper(
+    aCallback, aPref, aClosure, Preferences::ExactMatch, /* isPriority */ true);
+}
+
 /* static */ nsresult
 Preferences::RegisterCallback(PrefChangedFunc aCallback,
                               const char* aPref,
@@ -4983,20 +4994,8 @@ Preferences::RegisterCallback(PrefChangedFunc aCallback,
   MOZ_ASSERT(aCallback);
   NS_ENSURE_TRUE(InitStaticMembers(), NS_ERROR_NOT_AVAILABLE);
 
-  ValueObserverHashKey hashKey(aPref, aCallback, aMatchKind);
-  RefPtr<ValueObserver> observer;
-  gObserverTable->Get(&hashKey, getter_AddRefs(observer));
-  if (observer) {
-    observer->AppendClosure(aClosure);
-    return NS_OK;
-  }
-
-  observer = new ValueObserver(aPref, aCallback, aMatchKind);
-  observer->AppendClosure(aClosure);
-  nsresult rv = AddStrongObserver(observer, aPref);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  gObserverTable->Put(observer, observer);
+  RegisterCallbackHelper(
+    aCallback, aPref, aClosure, aMatchKind, /* isPriority */ false);
   return NS_OK;
 }
 
@@ -5037,15 +5036,14 @@ Preferences::UnregisterCallback(PrefChangedFunc aCallback,
   observer->RemoveClosure(aClosure);
   if (observer->HasNoClosures()) {
     // Delete the callback since its list of closures is empty.
+    MOZ_ALWAYS_SUCCEEDS(
+      PREF_UnregisterCallback(aPref, NotifyObserver, observer));
+
     gObserverTable->Remove(observer);
   }
   return NS_OK;
 }
 
-// We insert cache observers using RegisterPriorityCallback to ensure they are
-// called prior to ordinary pref observers. Doing this ensures that ordinary
-// observers will never get stale values from cache variables.
-
 static void
 BoolVarChanged(const char* aPref, void* aClosure)
 {
@@ -5076,7 +5074,7 @@ Preferences::AddBoolVarCache(bool* aCache, const char* aPref, bool aDefault)
   data->mCacheLocation = aCache;
   data->mDefaultValueBool = aDefault;
   CacheDataAppendElement(data);
-  RegisterPriorityCallback(BoolVarChanged, aPref, data);
+  RegisterVarCacheCallback(BoolVarChanged, aPref, data);
   return NS_OK;
 }
 
@@ -5103,7 +5101,7 @@ Preferences::AddIntVarCache(int32_t* aCache,
   data->mCacheLocation = aCache;
   data->mDefaultValueInt = aDefault;
   CacheDataAppendElement(data);
-  RegisterPriorityCallback(IntVarChanged, aPref, data);
+  RegisterVarCacheCallback(IntVarChanged, aPref, data);
   return NS_OK;
 }
 
@@ -5130,7 +5128,7 @@ Preferences::AddUintVarCache(uint32_t* aCache,
   data->mCacheLocation = aCache;
   data->mDefaultValueUint = aDefault;
   CacheDataAppendElement(data);
-  RegisterPriorityCallback(UintVarChanged, aPref, data);
+  RegisterVarCacheCallback(UintVarChanged, aPref, data);
   return NS_OK;
 }
 
@@ -5159,7 +5157,7 @@ Preferences::AddAtomicUintVarCache(Atomic<uint32_t, Order>* aCache,
   data->mCacheLocation = aCache;
   data->mDefaultValueUint = aDefault;
   CacheDataAppendElement(data);
-  RegisterPriorityCallback(AtomicUintVarChanged<Order>, aPref, data);
+  RegisterVarCacheCallback(AtomicUintVarChanged<Order>, aPref, data);
   return NS_OK;
 }
 
@@ -5192,7 +5190,7 @@ Preferences::AddFloatVarCache(float* aCache, const char* aPref, float aDefault)
   data->mCacheLocation = aCache;
   data->mDefaultValueFloat = aDefault;
   CacheDataAppendElement(data);
-  RegisterPriorityCallback(FloatVarChanged, aPref, data);
+  RegisterVarCacheCallback(FloatVarChanged, aPref, data);
   return NS_OK;
 }
 
diff --git a/netwerk/cookie/nsCookieService.cpp b/netwerk/cookie/nsCookieService.cpp
index 0502905355a7..5142ad24e5c9 100644
--- a/netwerk/cookie/nsCookieService.cpp
+++ b/netwerk/cookie/nsCookieService.cpp
@@ -1338,6 +1338,8 @@ nsCookieService::TryInitDB(bool aRecreateDB)
       // No more upgrades. Update the schema version.
       rv = mDefaultDBState->syncConn->SetSchemaVersion(COOKIES_SCHEMA_VERSION);
       NS_ENSURE_SUCCESS(rv, RESULT_RETRY);
+
+      Telemetry::Accumulate(Telemetry::MOZ_SQLITE_COOKIES_OLD_SCHEMA, dbSchemaVersion);
       MOZ_FALLTHROUGH;
 
     case COOKIES_SCHEMA_VERSION:
@@ -1429,6 +1431,7 @@ nsCookieService::TryInitDB(bool aRecreateDB)
       gCookieService->ImportCookies(oldCookieFile);
       oldCookieFile->Remove(false);
       gCookieService->mDBState = initialState;
+      Telemetry::Accumulate(Telemetry::MOZ_SQLITE_COOKIES_OLD_SCHEMA, 0);
     });
 
   NS_DispatchToMainThread(runnable);
diff --git a/taskcluster/ci/l10n/kind.yml b/taskcluster/ci/l10n/kind.yml
index 482c15d36484..a2304fdb525b 100644
--- a/taskcluster/ci/l10n/kind.yml
+++ b/taskcluster/ci/l10n/kind.yml
@@ -46,10 +46,6 @@ job-template:
          android-api-16-l10n:
            in-tree: android-build
          win.*: null
-   secrets:
-      by-build-platform:
-         default: false
-         android-api-16-l10n: true
    toolchains:
       by-build-platform:
          default: []
@@ -114,8 +110,7 @@ job-template:
       actions:
          by-build-platform:
             default: [clone-locales list-locales setup repack summary]
-            android-api-16-l10n: [get-secrets
-                                  clone-locales list-locales setup repack
+            android-api-16-l10n: [clone-locales list-locales setup repack
                                   upload-repacks summary]
       script:
          by-build-platform:
diff --git a/taskcluster/ci/nightly-l10n/kind.yml b/taskcluster/ci/nightly-l10n/kind.yml
index 0d04fdda8ed8..f8688f3f6adb 100644
--- a/taskcluster/ci/nightly-l10n/kind.yml
+++ b/taskcluster/ci/nightly-l10n/kind.yml
@@ -49,10 +49,6 @@ job-template:
          android-api-16-nightly:
            in-tree: android-build
          win.*: null
-   secrets:
-      by-build-platform:
-         default: false
-         android-api-16-nightly: true
    toolchains:
       by-build-platform:
          default: []
@@ -175,8 +171,7 @@ job-template:
          by-build-platform:
             default: ['clone-locales', 'list-locales', 'setup', 'repack',
                       'submit-to-balrog', 'summary']
-            android-api-16-nightly: ['get-secrets',
-                                     'clone-locales', 'list-locales', 'setup', 'repack',
+            android-api-16-nightly: ['clone-locales', 'list-locales', 'setup', 'repack',
                                      'upload-repacks', 'submit-to-balrog', 'summary']
       script:
          by-build-platform:
diff --git a/taskcluster/taskgraph/transforms/l10n.py b/taskcluster/taskgraph/transforms/l10n.py
index 75fbe83b49cc..42e9fc781175 100644
--- a/taskcluster/taskgraph/transforms/l10n.py
+++ b/taskcluster/taskgraph/transforms/l10n.py
@@ -107,13 +107,6 @@ l10n_description_schema = Schema({
 
     Optional('toolchains'): _by_platform([basestring]),
 
-    # The set of secret names to which the task has access; these are prefixed
-    # with `project/releng/gecko/{treeherder.kind}/level-{level}/`.  Setting
-    # this will enable any worker features required and set the task's scopes
-    # appropriately.  `true` here means ['*'], all secrets.  Not supported on
-    # Windows
-    Required('secrets', default=False): _by_platform(Any(bool, [basestring])),
-
     # Information for treeherder
     Required('treeherder'): {
         # Platform to display the task on in treeherder
@@ -258,7 +251,6 @@ def handle_keyed_by(config, jobs):
         "description",
         "run-time",
         "docker-image",
-        "secrets",
         "toolchains",
         "tooltool",
         "env",
@@ -393,7 +385,6 @@ def make_job_description(config, jobs):
                 'script': job['mozharness']['script'],
                 'actions': job['mozharness']['actions'],
                 'options': job['mozharness']['options'],
-                'secrets': job['secrets'],
             },
             'attributes': job['attributes'],
             'treeherder': {
diff --git a/testing/mozharness/configs/single_locale/tc_android-api-16.py b/testing/mozharness/configs/single_locale/tc_android-api-16.py
index a551b13bb5cd..509754d0fe9e 100644
--- a/testing/mozharness/configs/single_locale/tc_android-api-16.py
+++ b/testing/mozharness/configs/single_locale/tc_android-api-16.py
@@ -15,37 +15,4 @@ config = {
     },
     "mozilla_dir": "src/",
     "simple_name_move": True,
-    'secret_files': [
-        {'filename': '/builds/gapi.data',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/gapi.data',
-         'min_scm_level': 1},
-        {'filename': '/builds/mozilla-fennec-geoloc-api.key',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/mozilla-fennec-geoloc-api.key',
-         'min_scm_level': 2, 'default': 'try-build-has-no-secrets'},
-        {'filename': '/builds/adjust-sdk.token',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/adjust-sdk.token',
-         'min_scm_level': 2, 'default': 'try-build-has-no-secrets'},
-        {'filename': '/builds/adjust-sdk-beta.token',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/adjust-sdk-beta.token',
-         'min_scm_level': 2, 'default': 'try-build-has-no-secrets'},
-        {'filename': '/builds/leanplum-sdk-release.token',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/leanplum-sdk-release.token',
-         'min_scm_level': 2, 'default': 'try-build-has-no-secrets'},
-        {'filename': '/builds/leanplum-sdk-beta.token',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/leanplum-sdk-beta.token',
-         'min_scm_level': 2, 'default': 'try-build-has-no-secrets'},
-        {'filename': '/builds/leanplum-sdk-nightly.token',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/leanplum-sdk-nightly.token',
-         'min_scm_level': 2, 'default': 'try-build-has-no-secrets'},
-        {'filename': '/builds/pocket-api-release.token',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/pocket-api-release.token',
-         'min_scm_level': 2, 'default': 'try-build-has-no-secrets'},
-        {'filename': '/builds/pocket-api-beta.token',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/pocket-api-beta.token',
-         'min_scm_level': 2, 'default': 'try-build-has-no-secrets'},
-        {'filename': '/builds/pocket-api-nightly.token',
-         'secret_name': 'project/releng/gecko/build/level-%(scm-level)s/pocket-api-nightly.token',
-         'min_scm_level': 2, 'default': 'try-build-has-no-secrets'},
-
-    ],
 }
diff --git a/testing/mozharness/scripts/mobile_l10n.py b/testing/mozharness/scripts/mobile_l10n.py
index bc3fb748f992..10bda50a8793 100755
--- a/testing/mozharness/scripts/mobile_l10n.py
+++ b/testing/mozharness/scripts/mobile_l10n.py
@@ -38,7 +38,6 @@ from mozharness.mozilla.tooltool import TooltoolMixin
 from mozharness.base.vcs.vcsbase import MercurialScript
 from mozharness.mozilla.l10n.locales import LocalesMixin
 from mozharness.mozilla.mock import MockMixin
-from mozharness.mozilla.secrets import SecretsMixin
 from mozharness.mozilla.updates.balrog import BalrogMixin
 from mozharness.base.python import VirtualenvMixin
 from mozharness.mozilla.taskcluster_helper import Taskcluster
@@ -48,7 +47,7 @@ from mozharness.mozilla.taskcluster_helper import Taskcluster
 class MobileSingleLocale(MockMixin, LocalesMixin, ReleaseMixin,
                          MobileSigningMixin, TransferMixin, TooltoolMixin,
                          BuildbotMixin, PurgeMixin, MercurialScript, BalrogMixin,
-                         VirtualenvMixin, SecretsMixin):
+                         VirtualenvMixin):
     config_options = [[
         ['--locale', ],
         {"action": "extend",
@@ -125,7 +124,6 @@ class MobileSingleLocale(MockMixin, LocalesMixin, ReleaseMixin,
     def __init__(self, require_config_file=True):
         buildscript_kwargs = {
             'all_actions': [
-                "get-secrets",
                 "clobber",
                 "pull",
                 "clone-locales",
@@ -187,20 +185,6 @@ class MobileSingleLocale(MockMixin, LocalesMixin, ReleaseMixin,
         if 'MOZ_SIGNING_SERVERS' in os.environ:
             repack_env['MOZ_SIGN_CMD'] = \
                 subprocess.list2cmdline(self.query_moz_sign_cmd(formats=['jar']))
-
-        if self.query_is_nightly() or self.query_is_nightly_promotion():
-            if self.query_is_nightly():
-                # Nightly promotion needs to set update_channel but not do all
-                # the 'IS_NIGHTLY' automation parts, like uploading symbols
-                # (for now).
-                repack_env["IS_NIGHTLY"] = "yes"
-            # In branch_specifics.py we might set update_channel explicitly.
-            if c.get('update_channel'):
-                repack_env["MOZ_UPDATE_CHANNEL"] = c['update_channel']
-            else:  # Let's just give the generic channel based on branch.
-                repack_env["MOZ_UPDATE_CHANNEL"] = \
-                    "nightly-%s" % (c['branch'],)
-
         self.repack_env = repack_env
         return self.repack_env
 
diff --git a/toolkit/components/telemetry/Histograms.json b/toolkit/components/telemetry/Histograms.json
index f0e0db8a4b53..0cec3d613fba 100644
--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -4426,6 +4426,15 @@
     "n_buckets": 10,
     "description": "Time spent on SQLite read() (ms) *** No longer needed (bug 1156565). Delete histogram and accumulation code! ***"
   },
+  "MOZ_SQLITE_COOKIES_OLD_SCHEMA": {
+    "record_in_processes": ["main"],
+    "expires_in_version": "62",
+    "kind": "enumerated",
+    "n_values": 10,
+    "bug_numbers": [1412218],
+    "alert_emails": ["necko@mozilla.com", "junior@mozilla.com"],
+    "description": "Old schema version of the cookie database. 0 for having legacy cookies.txt."
+  },
   "MOZ_SQLITE_COOKIES_BLOCK_MAIN_THREAD_MS": {
     "record_in_processes": ["main"],
     "expires_in_version": "never",
diff --git a/toolkit/mozapps/installer/upload-files-APK.mk b/toolkit/mozapps/installer/upload-files-APK.mk
index 10279a8ae828..9bc3fc49cb4b 100644
--- a/toolkit/mozapps/installer/upload-files-APK.mk
+++ b/toolkit/mozapps/installer/upload-files-APK.mk
@@ -94,7 +94,6 @@ repackage_fennec = \
       $(UNPACKAGE) \
       $(GECKO_APP_AP_PATH)/gecko-nodeps.ap_ \
     --omnijar $(MOZ_PKG_DIR)/$(OMNIJAR_NAME) \
-    --classes-dex $(GECKO_APP_AP_PATH)/classes.dex \
     --output $(PACKAGE:.apk=-unsigned-unaligned.apk) && \
   $(call RELEASE_SIGN_ANDROID_APK,$(PACKAGE:.apk=-unsigned-unaligned.apk),$(PACKAGE))