--- a/layout/painting/nsDisplayItemTypesList.h
+++ b/layout/painting/nsDisplayItemTypesList.h
@@ -1,14 +1,15 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* 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/. */
 // IWYU pragma: private, include "nsDisplayList.h"
+DECLARE_DISPLAY_ITEM_TYPE(ASYNC_ZOOM, TYPE_RENDERS_NO_IMAGES)
 DECLARE_DISPLAY_ITEM_TYPE(ALT_FEEDBACK, 0)
 DECLARE_DISPLAY_ITEM_TYPE(BACKGROUND, 0)
 DECLARE_DISPLAY_ITEM_TYPE(THEMED_BACKGROUND, TYPE_RENDERS_NO_IMAGES)
 DECLARE_DISPLAY_ITEM_TYPE(BACKGROUND_COLOR, TYPE_RENDERS_NO_IMAGES)
 DECLARE_DISPLAY_ITEM_TYPE(BLEND_CONTAINER, TYPE_RENDERS_NO_IMAGES)
 DECLARE_DISPLAY_ITEM_TYPE(TABLE_BLEND_CONTAINER, TYPE_RENDERS_NO_IMAGES)
 DECLARE_DISPLAY_ITEM_TYPE(BLEND_MODE, TYPE_RENDERS_NO_IMAGES)
 DECLARE_DISPLAY_ITEM_TYPE(TABLE_BLEND_MODE, TYPE_RENDERS_NO_IMAGES)

--- a/layout/painting/nsDisplayList.cpp
+++ b/layout/painting/nsDisplayList.cpp
@@ -7830,16 +7830,45 @@ bool nsDisplayZoom::ComputeVisibility(ns
   removed = removed.ScaleToOtherAppUnitsRoundIn(mAPD, mParentAPD);
   // aVisibleRegion = aVisibleRegion - removed (modulo any simplifications
   // SubtractFromVisibleRegion does)
   aBuilder->SubtractFromVisibleRegion(aVisibleRegion, removed);
 
   return retval;
 }
 
+nsDisplayAsyncZoom::nsDisplayAsyncZoom(nsDisplayListBuilder* aBuilder,
+                                       nsIFrame* aFrame,
+                                       nsDisplayList* aList,
+                                       const ActiveScrolledRoot* aActiveScrolledRoot,
+                                       mozilla::layers::FrameMetrics::ViewID aViewID)
+  : nsDisplayOwnLayer(aBuilder, aFrame, aList, aActiveScrolledRoot)
+  , mViewID(aViewID)
+{
+  MOZ_COUNT_CTOR(nsDisplayAsyncZoom);
+}
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+nsDisplayAsyncZoom::~nsDisplayAsyncZoom() {
+  MOZ_COUNT_DTOR(nsDisplayAsyncZoom);
+}
+#endif
+
+already_AddRefed<Layer>
+nsDisplayAsyncZoom::BuildLayer(nsDisplayListBuilder* aBuilder,
+                               LayerManager* aManager,
+                               const ContainerLayerParameters& aContainerParameters) {
+  RefPtr<Layer> layer =
+    nsDisplayOwnLayer::BuildLayer(aBuilder, aManager, aContainerParameters);
+
+  layer->SetIsAsyncZoomContainer(Some(mViewID));
+
+  return layer.forget();
+}
+
 ///////////////////////////////////////////////////
 // nsDisplayTransform Implementation
 //
 
 // Write #define UNIFIED_CONTINUATIONS here and in
 // TransformReferenceBox::Initialize to have the transform property try
 // to transform content with continuations as one unified block instead of
 // several smaller ones.  This is currently disabled because it doesn't work

--- a/layout/painting/nsDisplayList.h
+++ b/layout/painting/nsDisplayList.h
@@ -6034,16 +6034,61 @@ public:
   int32_t GetChildAppUnitsPerDevPixel() { return mAPD; }
   // Get the app units per dev pixel ratio of the parent document.
   int32_t GetParentAppUnitsPerDevPixel() { return mParentAPD; }
 
 private:
   int32_t mAPD, mParentAPD;
 };
 
+/**
+ * nsDisplayAsyncZoom is used for APZ zooming. It wraps the contents of the
+ * root content document's scroll frame, including fixed position content. It
+ * does not contain the scroll frame's scrollbars. It is clipped to the scroll
+ * frame's scroll port clip. It is not scrolled; only its non-fixed contents
+ * are scrolled. This item creates a container layer.
+ */
+class nsDisplayAsyncZoom : public nsDisplayOwnLayer {
+public:
+  nsDisplayAsyncZoom(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
+                     nsDisplayList* aList,
+                     const ActiveScrolledRoot* aActiveScrolledRoot,
+                     mozilla::layers::FrameMetrics::ViewID aViewID);
+  nsDisplayAsyncZoom(nsDisplayListBuilder* aBuilder,
+                     const nsDisplayAsyncZoom& aOther)
+    : nsDisplayOwnLayer(aBuilder, aOther)
+    , mViewID(aOther.mViewID)
+  {
+    MOZ_COUNT_CTOR(nsDisplayAsyncZoom);
+  }
+
+#ifdef NS_BUILD_REFCNT_LOGGING
+  virtual ~nsDisplayAsyncZoom();
+#endif
+
+  virtual nsDisplayWrapList* Clone(nsDisplayListBuilder* aBuilder) const override
+  {
+    return MakeDisplayItem<nsDisplayAsyncZoom>(aBuilder, *this);
+  }
+
+  virtual already_AddRefed<Layer> BuildLayer(nsDisplayListBuilder* aBuilder,
+                                             LayerManager* aManager,
+                                             const ContainerLayerParameters& aContainerParameters) override;
+  NS_DISPLAY_DECL_NAME("AsyncZoom", TYPE_ASYNC_ZOOM)
+  virtual LayerState GetLayerState(nsDisplayListBuilder* aBuilder,
+                                   LayerManager* aManager,
+                                   const ContainerLayerParameters& aParameters) override
+  {
+    return mozilla::LAYER_ACTIVE_FORCE;
+  }
+
+protected:
+  mozilla::layers::FrameMetrics::ViewID mViewID;
+};
+
 class nsDisplaySVGEffects: public nsDisplayWrapList {
 public:
   nsDisplaySVGEffects(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
                       nsDisplayList* aList, bool aHandleOpacity,
                       const ActiveScrolledRoot* aActiveScrolledRoot,
                       bool aClearClipChain = false);
   nsDisplaySVGEffects(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
                       nsDisplayList* aList, bool aHandleOpacity);