Merging upstream version 125.0.1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

83 files changed, 1131 insertions, 365 deletions

diff --git a/gfx/layers/BuildConstants.h b/gfx/layers/BuildConstants.h
index 6db150d136..cebdd35371 100644
--- a/gfx/layers/BuildConstants.h
+++ b/gfx/layers/BuildConstants.h
@@ -52,6 +52,13 @@ constexpr bool kIsAndroid =
     false;
 #endif
 
+constexpr bool kIsDmd =
+#ifdef MOZ_DMD
+    true;
+#else
+    false;
+#endif
+
 }  // namespace mozilla
 
 #endif  // BUILD_CONSTANTS_H_
diff --git a/gfx/layers/CanvasDrawEventRecorder.cpp b/gfx/layers/CanvasDrawEventRecorder.cpp
index 1bf928b816..af143bf5cb 100644
--- a/gfx/layers/CanvasDrawEventRecorder.cpp
+++ b/gfx/layers/CanvasDrawEventRecorder.cpp
@@ -8,6 +8,11 @@
 
 #include <string.h>
 
+#include "mozilla/dom/WorkerCommon.h"
+#include "mozilla/dom/WorkerPrivate.h"
+#include "mozilla/dom/WorkerRef.h"
+#include "mozilla/dom/WorkerRunnable.h"
+#include "mozilla/layers/TextureRecorded.h"
 #include "mozilla/layers/SharedSurfacesChild.h"
 #include "mozilla/StaticPrefs_gfx.h"
 #include "RecordedCanvasEventImpl.h"
@@ -34,7 +39,9 @@ static Maybe<ShmemAndHandle> CreateAndMapShmem(size_t aSize) {
   return Some(ShmemAndHandle{shmem.forget(), std::move(shmemHandle)});
 }
 
-CanvasDrawEventRecorder::CanvasDrawEventRecorder() {
+CanvasDrawEventRecorder::CanvasDrawEventRecorder(
+    dom::ThreadSafeWorkerRef* aWorkerRef)
+    : mWorkerRef(aWorkerRef), mIsOnWorker(!!aWorkerRef) {
   mDefaultBufferSize = ipc::SharedMemory::PageAlignedSize(
       StaticPrefs::gfx_canvas_remote_default_buffer_size());
   mMaxDefaultBuffers = StaticPrefs::gfx_canvas_remote_max_default_buffers();
@@ -43,7 +50,10 @@ CanvasDrawEventRecorder::CanvasDrawEventRecorder() {
   mDropBufferOnZero = mDropBufferLimit;
 }
 
+CanvasDrawEventRecorder::~CanvasDrawEventRecorder() { MOZ_ASSERT(!mWorkerRef); }
+
 bool CanvasDrawEventRecorder::Init(TextureType aTextureType,
+                                   TextureType aWebglTextureType,
                                    gfx::BackendType aBackendType,
                                    UniquePtr<Helpers> aHelpers) {
   NS_ASSERT_OWNINGTHREAD(CanvasDrawEventRecorder);
@@ -95,7 +105,7 @@ bool CanvasDrawEventRecorder::Init(TextureType aTextureType,
     return false;
   }
 
-  if (!mHelpers->InitTranslator(aTextureType, aBackendType,
+  if (!mHelpers->InitTranslator(aTextureType, aWebglTextureType, aBackendType,
                                 std::move(header->handle),
                                 std::move(bufferHandles), mDefaultBufferSize,
                                 std::move(readerSem), std::move(writerSem))) {
@@ -317,6 +327,106 @@ void CanvasDrawEventRecorder::CheckAndSignalReader() {
   } while (true);
 }
 
+void CanvasDrawEventRecorder::DetachResources() {
+  NS_ASSERT_OWNINGTHREAD(CanvasDrawEventRecorder);
+
+  DrawEventRecorderPrivate::DetachResources();
+
+  {
+    auto lockedPendingDeletions = mPendingDeletions.Lock();
+    mWorkerRef = nullptr;
+  }
+}
+
+void CanvasDrawEventRecorder::QueueProcessPendingDeletionsLocked(
+    RefPtr<CanvasDrawEventRecorder>&& aRecorder) {
+  if (!mWorkerRef) {
+    MOZ_RELEASE_ASSERT(
+        !mIsOnWorker,
+        "QueueProcessPendingDeletionsLocked called after worker shutdown!");
+
+    NS_DispatchToMainThread(NS_NewRunnableFunction(
+        "CanvasDrawEventRecorder::QueueProcessPendingDeletionsLocked",
+        [self = std::move(aRecorder)]() { self->ProcessPendingDeletions(); }));
+    return;
+  }
+
+  if (!NS_IsMainThread()) {
+    NS_DispatchToMainThread(NS_NewRunnableFunction(
+        "CanvasDrawEventRecorder::QueueProcessPendingDeletionsLocked",
+        [self = std::move(aRecorder)]() mutable {
+          self->QueueProcessPendingDeletions(std::move(self));
+        }));
+    return;
+  }
+
+  class ProcessPendingRunnable final : public dom::WorkerRunnable {
+   public:
+    ProcessPendingRunnable(dom::WorkerPrivate* aWorkerPrivate,
+                           RefPtr<CanvasDrawEventRecorder>&& aRecorder)
+        : dom::WorkerRunnable(aWorkerPrivate),
+          mRecorder(std::move(aRecorder)) {}
+
+    bool WorkerRun(JSContext*, dom::WorkerPrivate*) override {
+      RefPtr<CanvasDrawEventRecorder> recorder = std::move(mRecorder);
+      recorder->ProcessPendingDeletions();
+      return true;
+    }
+
+   private:
+    RefPtr<CanvasDrawEventRecorder> mRecorder;
+  };
+
+  auto task = MakeRefPtr<ProcessPendingRunnable>(mWorkerRef->Private(),
+                                                 std::move(aRecorder));
+  if (NS_WARN_IF(!task->Dispatch())) {
+    MOZ_CRASH("ProcessPendingRunnable leaked!");
+  }
+}
+
+void CanvasDrawEventRecorder::QueueProcessPendingDeletions(
+    RefPtr<CanvasDrawEventRecorder>&& aRecorder) {
+  auto lockedPendingDeletions = mPendingDeletions.Lock();
+  if (lockedPendingDeletions->empty()) {
+    // We raced to handle the deletions, and something got there first.
+    return;
+  }
+
+  QueueProcessPendingDeletionsLocked(std::move(aRecorder));
+}
+
+void CanvasDrawEventRecorder::AddPendingDeletion(
+    std::function<void()>&& aPendingDeletion) {
+  PendingDeletionsVector pendingDeletions;
+
+  {
+    auto lockedPendingDeletions = mPendingDeletions.Lock();
+    bool wasEmpty = lockedPendingDeletions->empty();
+    lockedPendingDeletions->emplace_back(std::move(aPendingDeletion));
+
+    MOZ_RELEASE_ASSERT(!mIsOnWorker || mWorkerRef,
+                       "AddPendingDeletion called after worker shutdown!");
+
+    // If we are not on the owning thread, we must queue an event to run the
+    // deletions, if we transitioned from empty to non-empty.
+    if ((mWorkerRef && !mWorkerRef->Private()->IsOnCurrentThread()) ||
+        (!mWorkerRef && !NS_IsMainThread())) {
+      if (wasEmpty) {
+        RefPtr<CanvasDrawEventRecorder> self(this);
+        QueueProcessPendingDeletionsLocked(std::move(self));
+      }
+      return;
+    }
+
+    // Otherwise, we can just run all of them right now.
+    pendingDeletions.swap(*lockedPendingDeletions);
+  }
+
+  for (const auto& pendingDeletion : pendingDeletions) {
+    pendingDeletion();
+  }
+}
+
 void CanvasDrawEventRecorder::StoreSourceSurfaceRecording(
     gfx::SourceSurface* aSurface, const char* aReason) {
   NS_ASSERT_OWNINGTHREAD(CanvasDrawEventRecorder);
diff --git a/gfx/layers/CanvasDrawEventRecorder.h b/gfx/layers/CanvasDrawEventRecorder.h
index a4b1261cfb..c9eacf27ac 100644
--- a/gfx/layers/CanvasDrawEventRecorder.h
+++ b/gfx/layers/CanvasDrawEventRecorder.h
@@ -21,6 +21,10 @@ namespace mozilla {
 
 using EventType = gfx::RecordedEvent::EventType;
 
+namespace dom {
+class ThreadSafeWorkerRef;
+}
+
 namespace layers {
 
 typedef mozilla::ipc::SharedMemoryBasic::Handle Handle;
@@ -31,7 +35,8 @@ class CanvasDrawEventRecorder final : public gfx::DrawEventRecorderPrivate,
  public:
   MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(CanvasDrawEventRecorder, final)
 
-  CanvasDrawEventRecorder();
+  explicit CanvasDrawEventRecorder(dom::ThreadSafeWorkerRef* aWorkerRef);
+  ~CanvasDrawEventRecorder() override;
 
   enum class State : uint32_t {
     Processing,
@@ -68,6 +73,7 @@ class CanvasDrawEventRecorder final : public gfx::DrawEventRecorderPrivate,
     virtual ~Helpers() = default;
 
     virtual bool InitTranslator(TextureType aTextureType,
+                                TextureType aWebglTextureType,
                                 gfx::BackendType aBackendType,
                                 Handle&& aReadHandle,
                                 nsTArray<Handle>&& aBufferHandles,
@@ -89,8 +95,8 @@ class CanvasDrawEventRecorder final : public gfx::DrawEventRecorderPrivate,
     virtual bool RestartReader() = 0;
   };
 
-  bool Init(TextureType aTextureType, gfx::BackendType aBackendType,
-            UniquePtr<Helpers> aHelpers);
+  bool Init(TextureType aTextureType, TextureType aWebglTextureType,
+            gfx::BackendType aBackendType, UniquePtr<Helpers> aHelpers);
 
   /**
    * Record an event for processing by the CanvasParent's CanvasTranslator.
@@ -98,6 +104,10 @@ class CanvasDrawEventRecorder final : public gfx::DrawEventRecorderPrivate,
    */
   void RecordEvent(const gfx::RecordedEvent& aEvent) final;
 
+  void DetachResources() final;
+
+  void AddPendingDeletion(std::function<void()>&& aPendingDeletion) override;
+
   void StoreSourceSurfaceRecording(gfx::SourceSurface* aSurface,
                                    const char* aReason) final;
 
@@ -134,6 +144,11 @@ class CanvasDrawEventRecorder final : public gfx::DrawEventRecorderPrivate,
 
   void CheckAndSignalReader();
 
+  void QueueProcessPendingDeletions(
+      RefPtr<CanvasDrawEventRecorder>&& aRecorder);
+  void QueueProcessPendingDeletionsLocked(
+      RefPtr<CanvasDrawEventRecorder>&& aRecorder);
+
   size_t mDefaultBufferSize;
   size_t mMaxDefaultBuffers;
   uint32_t mMaxSpinCount;
@@ -173,6 +188,9 @@ class CanvasDrawEventRecorder final : public gfx::DrawEventRecorderPrivate,
 
   UniquePtr<CrossProcessSemaphore> mWriterSemaphore;
   UniquePtr<CrossProcessSemaphore> mReaderSemaphore;
+
+  RefPtr<dom::ThreadSafeWorkerRef> mWorkerRef;
+  bool mIsOnWorker = false;
 };
 
 }  // namespace layers
diff --git a/gfx/layers/FrameMetrics.cpp b/gfx/layers/FrameMetrics.cpp
index 5d82b7f295..86fdd5ffd6 100644
--- a/gfx/layers/FrameMetrics.cpp
+++ b/gfx/layers/FrameMetrics.cpp
@@ -147,12 +147,10 @@ CSSSize FrameMetrics::CalculateCompositedSizeInCssPixels(
   return aCompositionBounds.Size() / aZoom;
 }
 
-std::pair<bool, CSSPoint> FrameMetrics::ApplyAbsoluteScrollUpdateFrom(
-    const ScrollPositionUpdate& aUpdate) {
-  CSSPoint oldVisualOffset = GetVisualScrollOffset();
+bool FrameMetrics::ApplyScrollUpdateFrom(const ScrollPositionUpdate& aUpdate) {
   // In applying a main-thread scroll update, try to preserve the relative
   // offset between the visual and layout viewports.
-  CSSPoint relativeOffset = oldVisualOffset - GetLayoutScrollOffset();
+  CSSPoint relativeOffset = GetVisualScrollOffset() - GetLayoutScrollOffset();
   MOZ_ASSERT(IsRootContent() || relativeOffset == CSSPoint());
   // We need to set the two offsets together, otherwise a subsequent
   // RecalculateLayoutViewportOffset() could see divergent layout and
@@ -160,7 +158,7 @@ std::pair<bool, CSSPoint> FrameMetrics::ApplyAbsoluteScrollUpdateFrom(
   bool offsetChanged = SetLayoutScrollOffset(aUpdate.GetDestination());
   offsetChanged |=
       ClampAndSetVisualScrollOffset(aUpdate.GetDestination() + relativeOffset);
-  return {offsetChanged, GetVisualScrollOffset() - oldVisualOffset};
+  return offsetChanged;
 }
 
 CSSPoint FrameMetrics::ApplyRelativeScrollUpdateFrom(
@@ -168,7 +166,7 @@ CSSPoint FrameMetrics::ApplyRelativeScrollUpdateFrom(
   MOZ_ASSERT(aUpdate.GetType() == ScrollUpdateType::Relative);
   CSSPoint origin = GetVisualScrollOffset();
   CSSPoint delta = (aUpdate.GetDestination() - aUpdate.GetSource());
-  ClampAndSetVisualScrollOffset(origin + delta);
+  SetVisualScrollOffset(origin + delta);
   return GetVisualScrollOffset() - origin;
 }
 
diff --git a/gfx/layers/FrameMetrics.h b/gfx/layers/FrameMetrics.h
index 6b7a41bf25..5d13d36703 100644
--- a/gfx/layers/FrameMetrics.h
+++ b/gfx/layers/FrameMetrics.h
@@ -243,11 +243,9 @@ struct FrameMetrics {
   }
 
   /*
-   * Returns true if the layout scroll offset or visual scroll offset changed
-   * and returns the visual scroll offset change delta.
+   * Returns true if the layout scroll offset or visual scroll offset changed.
    */
-  std::pair<bool, CSSPoint> ApplyAbsoluteScrollUpdateFrom(
-      const ScrollPositionUpdate& aUpdate);
+  bool ApplyScrollUpdateFrom(const ScrollPositionUpdate& aUpdate);
 
   /**
    * Applies the relative scroll offset update contained in aOther to the
@@ -893,6 +891,12 @@ struct ScrollMetadata {
     mScrollUpdates.AppendElements(std::move(aUpdates));
   }
 
+  void PrependUpdates(const nsTArray<ScrollPositionUpdate>& aUpdates) {
+    MOZ_ASSERT(!aUpdates.IsEmpty());
+
+    mScrollUpdates.InsertElementsAt(0, aUpdates);
+  }
+
  private:
   FrameMetrics mMetrics;
 
diff --git a/gfx/layers/ImageContainer.cpp b/gfx/layers/ImageContainer.cpp
index 8a4c03f5a2..bdedccf56d 100644
--- a/gfx/layers/ImageContainer.cpp
+++ b/gfx/layers/ImageContainer.cpp
@@ -34,7 +34,7 @@
 #include "nsProxyRelease.h"
 #include "nsISupportsUtils.h"  // for NS_IF_ADDREF
 
-#ifdef XP_MACOSX
+#ifdef XP_DARWIN
 #  include "MacIOSurfaceImage.h"
 #endif
 
@@ -563,7 +563,7 @@ ImageContainer::GetD3D11YCbCrRecycleAllocator(
 }
 #endif
 
-#ifdef XP_MACOSX
+#ifdef XP_DARWIN
 already_AddRefed<MacIOSurfaceRecycleAllocator>
 ImageContainer::GetMacIOSurfaceRecycleAllocator() {
   RecursiveMutexAutoLock lock(mRecursiveMutex);
diff --git a/gfx/layers/ImageContainer.h b/gfx/layers/ImageContainer.h
index 253ba417eb..6fa12cf195 100644
--- a/gfx/layers/ImageContainer.h
+++ b/gfx/layers/ImageContainer.h
@@ -63,7 +63,7 @@ class MemoryOrShmem;
 class D3D11RecycleAllocator;
 class D3D11YCbCrRecycleAllocator;
 #endif
-#ifdef XP_MACOSX
+#ifdef XP_DARWIN
 class MacIOSurfaceRecycleAllocator;
 #endif
 class SurfaceDescriptorBuffer;
@@ -80,7 +80,7 @@ class GLImage;
 class SharedRGBImage;
 #ifdef MOZ_WIDGET_ANDROID
 class SurfaceTextureImage;
-#elif defined(XP_MACOSX)
+#elif defined(XP_DARWIN)
 class MacIOSurfaceImage;
 #elif MOZ_WIDGET_GTK
 class DMABUFSurfaceImage;
@@ -159,7 +159,7 @@ class Image {
 #ifdef MOZ_WIDGET_ANDROID
   virtual SurfaceTextureImage* AsSurfaceTextureImage() { return nullptr; }
 #endif
-#ifdef XP_MACOSX
+#ifdef XP_DARWIN
   virtual MacIOSurfaceImage* AsMacIOSurfaceImage() { return nullptr; }
 #endif
   virtual PlanarYCbCrImage* AsPlanarYCbCrImage() { return nullptr; }
@@ -191,8 +191,8 @@ class Image {
   virtual ~Image() = default;
 
   mozilla::EnumeratedArray<mozilla::layers::LayersBackend,
-                           mozilla::layers::LayersBackend::LAYERS_LAST,
-                           UniquePtr<ImageBackendData>>
+                           UniquePtr<ImageBackendData>,
+                           size_t(mozilla::layers::LayersBackend::LAYERS_LAST)>
       mBackendData;
 
   void* mImplData;
@@ -530,7 +530,7 @@ class ImageContainer final : public SupportsThreadSafeWeakPtr<ImageContainer> {
       KnowsCompositor* aKnowsCompositor);
 #endif
 
-#ifdef XP_MACOSX
+#ifdef XP_DARWIN
   already_AddRefed<MacIOSurfaceRecycleAllocator>
   GetMacIOSurfaceRecycleAllocator();
 #endif
@@ -618,7 +618,7 @@ class ImageContainer final : public SupportsThreadSafeWeakPtr<ImageContainer> {
   RefPtr<D3D11YCbCrRecycleAllocator> mD3D11YCbCrRecycleAllocator
       MOZ_GUARDED_BY(mRecursiveMutex);
 #endif
-#ifdef XP_MACOSX
+#ifdef XP_DARWIN
   RefPtr<MacIOSurfaceRecycleAllocator> mMacIOSurfaceRecycleAllocator
       MOZ_GUARDED_BY(mRecursiveMutex);
 #endif
diff --git a/gfx/layers/NativeLayerCA.h b/gfx/layers/NativeLayerCA.h
index 1424c1251f..b41ac36c23 100644
--- a/gfx/layers/NativeLayerCA.h
+++ b/gfx/layers/NativeLayerCA.h
@@ -6,7 +6,7 @@
 #ifndef mozilla_layers_NativeLayerCA_h
 #define mozilla_layers_NativeLayerCA_h
 
-#include <IOSurface/IOSurface.h>
+#include <IOSurface/IOSurfaceRef.h>
 
 #include <deque>
 #include <unordered_map>
@@ -39,7 +39,9 @@ class RenderMacIOSurfaceTextureHost;
 
 namespace layers {
 
+#ifdef XP_MACOSX
 class NativeLayerRootSnapshotterCA;
+#endif
 class SurfacePoolHandleCA;
 
 enum class VideoLowPowerType {
@@ -102,8 +104,10 @@ class NativeLayerRootCA : public NativeLayerRoot {
   bool CommitToScreen() override;
 
   void CommitOffscreen();
+#ifdef XP_MACOSX
   void OnNativeLayerRootSnapshotterDestroyed(
       NativeLayerRootSnapshotterCA* aNativeLayerRootSnapshotter);
+#endif
 
   // Enters a mode during which CommitToScreen(), when called on a non-main
   // thread, will not apply any updates to the CALayer tree.
@@ -139,7 +143,7 @@ class NativeLayerRootCA : public NativeLayerRoot {
 
   void SetWindowIsFullscreen(bool aFullscreen);
 
-  VideoLowPowerType CheckVideoLowPower(const MutexAutoLock& aProofOfLock);
+  VideoLowPowerType CheckVideoLowPower();
 
  protected:
   explicit NativeLayerRootCA(CALayer* aLayer);
@@ -149,7 +153,8 @@ class NativeLayerRootCA : public NativeLayerRoot {
     explicit Representation(CALayer* aRootCALayer);
     ~Representation();
     void Commit(WhichRepresentation aRepresentation,
-                const nsTArray<RefPtr<NativeLayerCA>>& aSublayers);
+                const nsTArray<RefPtr<NativeLayerCA>>& aSublayers,
+                bool aWindowIsFullscreen);
     CALayer* mRootCALayer = nullptr;  // strong
     bool mMutatedLayerStructure = false;
   };
@@ -160,7 +165,9 @@ class NativeLayerRootCA : public NativeLayerRoot {
   Mutex mMutex MOZ_UNANNOTATED;  // protects all other fields
   Representation mOnscreenRepresentation;
   Representation mOffscreenRepresentation;
+#ifdef XP_MACOSX
   NativeLayerRootSnapshotterCA* mWeakSnapshotter = nullptr;
+#endif
   nsTArray<RefPtr<NativeLayerCA>> mSublayers;  // in z-order
   float mBackingScale = 1.0f;
   bool mMutated = false;
@@ -188,6 +195,7 @@ class NativeLayerRootCA : public NativeLayerRoot {
 
 class RenderSourceNLRS;
 
+#ifdef XP_MACOSX
 class NativeLayerRootSnapshotterCA final : public NativeLayerRootSnapshotter {
  public:
   static UniquePtr<NativeLayerRootSnapshotterCA> Create(
@@ -217,6 +225,7 @@ class NativeLayerRootSnapshotterCA final : public NativeLayerRootSnapshotter {
   RefPtr<RenderSourceNLRS> mSnapshot;
   CARenderer* mRenderer = nullptr;  // strong
 };
+#endif
 
 // NativeLayerCA wraps a CALayer and lets you draw to it. It ensures that only
 // fully-drawn frames make their way to the screen, by maintaining a swap chain
@@ -260,6 +269,8 @@ class NativeLayerCA : public NativeLayer {
 
   void AttachExternalImage(wr::RenderTextureHost* aExternalImage) override;
 
+  void SetRootWindowIsFullscreen(bool aFullscreen);
+
  protected:
   friend class NativeLayerRootCA;
 
@@ -324,7 +335,8 @@ class NativeLayerCA : public NativeLayer {
   Maybe<SurfaceWithInvalidRegion> GetUnusedSurfaceAndCleanUp(
       const MutexAutoLock& aProofOfLock);
 
-  bool IsVideo(const MutexAutoLock& aProofOfLock);
+  bool IsVideo();
+  bool IsVideoAndLocked(const MutexAutoLock& aProofOfLock);
   bool ShouldSpecializeVideo(const MutexAutoLock& aProofOfLock);
   bool HasExtent() const { return mHasExtent; }
   void SetHasExtent(bool aHasExtent) { mHasExtent = aHasExtent; }
@@ -468,10 +480,10 @@ class NativeLayerCA : public NativeLayer {
   bool mSurfaceIsFlipped = false;
   CFTypeRefPtr<CGColorRef> mColor;
   const bool mIsOpaque = false;
+  bool mRootWindowIsFullscreen = false;
   bool mSpecializeVideo = false;
   bool mHasExtent = false;
   bool mIsDRM = false;
-  bool mIsTextureHostVideo = false;
 
 #ifdef NIGHTLY_BUILD
   // Track the consistency of our caller's API usage. Layers that are drawn
diff --git a/gfx/layers/NativeLayerCA.mm b/gfx/layers/NativeLayerCA.mm
index bd0b50e91b..42a889184e 100644
--- a/gfx/layers/NativeLayerCA.mm
+++ b/gfx/layers/NativeLayerCA.mm
@@ -5,10 +5,12 @@
 
 #include "mozilla/layers/NativeLayerCA.h"
 
-#import <AppKit/NSAnimationContext.h>
-#import <AppKit/NSColor.h>
+#ifdef XP_MACOSX
+#  import <AppKit/NSAnimationContext.h>
+#  import <AppKit/NSColor.h>
+#  import <OpenGL/gl.h>
+#endif
 #import <AVFoundation/AVFoundation.h>
-#import <OpenGL/gl.h>
 #import <QuartzCore/QuartzCore.h>
 
 #include <algorithm>
@@ -19,7 +21,11 @@
 
 #include "gfxUtils.h"
 #include "GLBlitHelper.h"
-#include "GLContextCGL.h"
+#ifdef XP_MACOSX
+#  include "GLContextCGL.h"
+#else
+#  include "GLContextEAGL.h"
+#endif
 #include "GLContextProvider.h"
 #include "MozFramebuffer.h"
 #include "mozilla/gfx/Swizzle.h"
@@ -45,7 +51,9 @@ using gfx::IntSize;
 using gfx::Matrix4x4;
 using gfx::SurfaceFormat;
 using gl::GLContext;
+#ifdef XP_MACOSX
 using gl::GLContextCGL;
+#endif
 
 static Maybe<Telemetry::LABELS_GFX_MACOS_VIDEO_LOW_POWER>
 VideoLowPowerTypeToTelemetryType(VideoLowPowerType aVideoLowPower) {
@@ -150,13 +158,23 @@ class AsyncReadbackBufferNLRS
 // protection, see bug 1585523.
 struct MOZ_STACK_CLASS AutoCATransaction final {
   AutoCATransaction() {
+#ifdef XP_MACOSX
     [NSAnimationContext beginGrouping];
+#else
+    [CATransaction begin];
+#endif
     // By default, mutating a CALayer property triggers an animation which
     // smoothly transitions the property to the new value. We don't need these
     // animations, and this call turns them off:
     [CATransaction setDisableActions:YES];
   }
-  ~AutoCATransaction() { [NSAnimationContext endGrouping]; }
+  ~AutoCATransaction() {
+#ifdef XP_MACOSX
+    [NSAnimationContext endGrouping];
+#else
+    [CATransaction commit];
+#endif
+  }
 };
 
 /* static */ already_AddRefed<NativeLayerRootCA>
@@ -178,9 +196,9 @@ static CALayer* MakeOffscreenRootCALayer() {
   // down).
   AutoCATransaction transaction;
   CALayer* layer = [CALayer layer];
-  layer.position = NSZeroPoint;
-  layer.bounds = NSZeroRect;
-  layer.anchorPoint = NSZeroPoint;
+  layer.position = CGPointZero;
+  layer.bounds = CGRectZero;
+  layer.anchorPoint = CGPointZero;
   layer.contentsGravity = kCAGravityTopLeft;
   layer.masksToBounds = YES;
   layer.geometryFlipped = YES;
@@ -226,6 +244,7 @@ void NativeLayerRootCA::AppendLayer(NativeLayer* aLayer) {
 
   mSublayers.AppendElement(layerCA);
   layerCA->SetBackingScale(mBackingScale);
+  layerCA->SetRootWindowIsFullscreen(mWindowIsFullscreen);
   ForAllRepresentations(
       [&](Representation& r) { r.mMutatedLayerStructure = true; });
 }
@@ -257,6 +276,7 @@ void NativeLayerRootCA::SetLayers(
     RefPtr<NativeLayerCA> layerCA = layer->AsNativeLayerCA();
     MOZ_RELEASE_ASSERT(layerCA);
     layerCA->SetBackingScale(mBackingScale);
+    layerCA->SetRootWindowIsFullscreen(mWindowIsFullscreen);
     layersCA.AppendElement(std::move(layerCA));
   }
 
@@ -306,47 +326,48 @@ bool NativeLayerRootCA::CommitToScreen() {
       return false;
     }
 
-    mOnscreenRepresentation.Commit(WhichRepresentation::ONSCREEN, mSublayers);
+    mOnscreenRepresentation.Commit(WhichRepresentation::ONSCREEN, mSublayers,
+                                   mWindowIsFullscreen);
 
     mCommitPending = false;
+  }
 
-    if (StaticPrefs::gfx_webrender_debug_dump_native_layer_tree_to_file()) {
-      static uint32_t sFrameID = 0;
-      uint32_t frameID = sFrameID++;
-
-      NSString* dirPath =
-          [NSString stringWithFormat:@"%@/Desktop/nativelayerdumps-%d",
-                                     NSHomeDirectory(), getpid()];
-      if ([NSFileManager.defaultManager createDirectoryAtPath:dirPath
-                                  withIntermediateDirectories:YES
-                                                   attributes:nil
-                                                        error:nullptr]) {
-        NSString* filename =
-            [NSString stringWithFormat:@"frame-%d.html", frameID];
-        NSString* filePath = [dirPath stringByAppendingPathComponent:filename];
-        DumpLayerTreeToFile([filePath UTF8String]);
-      } else {
-        NSLog(@"Failed to create directory %@", dirPath);
-      }
+  if (StaticPrefs::gfx_webrender_debug_dump_native_layer_tree_to_file()) {
+    static uint32_t sFrameID = 0;
+    uint32_t frameID = sFrameID++;
+
+    NSString* dirPath =
+        [NSString stringWithFormat:@"%@/Desktop/nativelayerdumps-%d",
+                                   NSHomeDirectory(), getpid()];
+    if ([NSFileManager.defaultManager createDirectoryAtPath:dirPath
+                                withIntermediateDirectories:YES
+                                                 attributes:nil
+                                                      error:nullptr]) {
+      NSString* filename =
+          [NSString stringWithFormat:@"frame-%d.html", frameID];
+      NSString* filePath = [dirPath stringByAppendingPathComponent:filename];
+      DumpLayerTreeToFile([filePath UTF8String]);
+    } else {
+      NSLog(@"Failed to create directory %@", dirPath);
     }
+  }
 
-    // Decide if we are going to emit telemetry about video low power on this
-    // commit.
-    static const int32_t TELEMETRY_COMMIT_PERIOD =
-        StaticPrefs::gfx_core_animation_low_power_telemetry_frames_AtStartup();
-    mTelemetryCommitCount =
-        (mTelemetryCommitCount + 1) % TELEMETRY_COMMIT_PERIOD;
-    if (mTelemetryCommitCount == 0) {
-      // Figure out if we are hitting video low power mode.
-      VideoLowPowerType videoLowPower = CheckVideoLowPower(lock);
-      EmitTelemetryForVideoLowPower(videoLowPower);
-    }
+  // Decide if we are going to emit telemetry about video low power on this
+  // commit.
+  static const int32_t TELEMETRY_COMMIT_PERIOD =
+      StaticPrefs::gfx_core_animation_low_power_telemetry_frames_AtStartup();
+  mTelemetryCommitCount = (mTelemetryCommitCount + 1) % TELEMETRY_COMMIT_PERIOD;
+  if (mTelemetryCommitCount == 0) {
+    // Figure out if we are hitting video low power mode.
+    VideoLowPowerType videoLowPower = CheckVideoLowPower();
+    EmitTelemetryForVideoLowPower(videoLowPower);
   }
 
   return true;
 }
 
 UniquePtr<NativeLayerRootSnapshotter> NativeLayerRootCA::CreateSnapshotter() {
+#ifdef XP_MACOSX
   MutexAutoLock lock(mMutex);
   MOZ_RELEASE_ASSERT(!mWeakSnapshotter,
                      "No NativeLayerRootSnapshotter for this NativeLayerRoot "
@@ -358,18 +379,24 @@ UniquePtr<NativeLayerRootSnapshotter> NativeLayerRootCA::CreateSnapshotter() {
     mWeakSnapshotter = cr.get();
   }
   return cr;
+#else
+  return nullptr;
+#endif
 }
 
+#ifdef XP_MACOSX
 void NativeLayerRootCA::OnNativeLayerRootSnapshotterDestroyed(
     NativeLayerRootSnapshotterCA* aNativeLayerRootSnapshotter) {
   MutexAutoLock lock(mMutex);
   MOZ_RELEASE_ASSERT(mWeakSnapshotter == aNativeLayerRootSnapshotter);
   mWeakSnapshotter = nullptr;
 }
+#endif
 
 void NativeLayerRootCA::CommitOffscreen() {
   MutexAutoLock lock(mMutex);
-  mOffscreenRepresentation.Commit(WhichRepresentation::OFFSCREEN, mSublayers);
+  mOffscreenRepresentation.Commit(WhichRepresentation::OFFSCREEN, mSublayers,
+                                  mWindowIsFullscreen);
 }
 
 template <typename F>
@@ -394,7 +421,8 @@ NativeLayerRootCA::Representation::~Representation() {
 
 void NativeLayerRootCA::Representation::Commit(
     WhichRepresentation aRepresentation,
-    const nsTArray<RefPtr<NativeLayerCA>>& aSublayers) {
+    const nsTArray<RefPtr<NativeLayerCA>>& aSublayers,
+    bool aWindowIsFullscreen) {
   bool mustRebuild = mMutatedLayerStructure;
   if (!mustRebuild) {
     // Check which type of update we need to do, if any.
@@ -439,7 +467,7 @@ void NativeLayerRootCA::Representation::Commit(
     mustRebuild |= layer->WillUpdateAffectLayers(aRepresentation);
     layer->ApplyChanges(aRepresentation, NativeLayerCA::UpdateType::All);
     CALayer* caLayer = layer->UnderlyingCALayer(aRepresentation);
-    if (!caLayer.masksToBounds || !NSIsEmptyRect(caLayer.bounds)) {
+    if (!caLayer.masksToBounds || !CGRectIsEmpty(caLayer.bounds)) {
       // This layer has an extent. If it didn't before, we need to rebuild.
       mustRebuild |= !layer->HasExtent();
       layer->SetHasExtent(true);
@@ -472,6 +500,7 @@ void NativeLayerRootCA::Representation::Commit(
   mMutatedLayerStructure = false;
 }
 
+#ifdef XP_MACOSX
 /* static */ UniquePtr<NativeLayerRootSnapshotterCA>
 NativeLayerRootSnapshotterCA::Create(NativeLayerRootCA* aLayerRoot,
                                      CALayer* aRootCALayer) {
@@ -498,6 +527,7 @@ NativeLayerRootSnapshotterCA::Create(NativeLayerRootCA* aLayerRoot,
       new NativeLayerRootSnapshotterCA(aLayerRoot, std::move(gl),
                                        aRootCALayer));
 }
+#endif
 
 void NativeLayerRootCA::DumpLayerTreeToFile(const char* aPath) {
   MutexAutoLock lock(mMutex);
@@ -519,7 +549,15 @@ void NativeLayerRootCA::DumpLayerTreeToFile(const char* aPath) {
 }
 
 void NativeLayerRootCA::SetWindowIsFullscreen(bool aFullscreen) {
-  mWindowIsFullscreen = aFullscreen;
+  MutexAutoLock lock(mMutex);
+
+  if (mWindowIsFullscreen != aFullscreen) {
+    mWindowIsFullscreen = aFullscreen;
+
+    for (auto layer : mSublayers) {
+      layer->SetRootWindowIsFullscreen(mWindowIsFullscreen);
+    }
+  }
 }
 
 /* static */ bool IsCGColorOpaqueBlack(CGColorRef aColor) {
@@ -541,8 +579,7 @@ void NativeLayerRootCA::SetWindowIsFullscreen(bool aFullscreen) {
   return components[componentCount - 1] >= 1.0f;
 }
 
-VideoLowPowerType NativeLayerRootCA::CheckVideoLowPower(
-    const MutexAutoLock& aProofOfLock) {
+VideoLowPowerType NativeLayerRootCA::CheckVideoLowPower() {
   // This deteremines whether the current layer contents qualify for the
   // macOS Core Animation video low power mode. Those requirements are
   // summarized at
@@ -572,7 +609,7 @@ VideoLowPowerType NativeLayerRootCA::CheckVideoLowPower(
 
       secondCALayer = topCALayer;
       topCALayer = topLayer->UnderlyingCALayer(WhichRepresentation::ONSCREEN);
-      topLayerIsVideo = topLayer->IsVideo(aProofOfLock);
+      topLayerIsVideo = topLayer->IsVideo();
       if (topLayerIsVideo) {
         ++videoLayerCount;
       }
@@ -641,6 +678,7 @@ VideoLowPowerType NativeLayerRootCA::CheckVideoLowPower(
   return VideoLowPowerType::LowPower;
 }
 
+#ifdef XP_MACOSX
 NativeLayerRootSnapshotterCA::NativeLayerRootSnapshotterCA(
     NativeLayerRootCA* aLayerRoot, RefPtr<GLContext>&& aGL,
     CALayer* aRootCALayer)
@@ -779,6 +817,7 @@ NativeLayerRootSnapshotterCA::CreateAsyncReadbackBuffer(const IntSize& aSize) {
                    LOCAL_GL_STREAM_READ);
   return MakeAndAddRef<AsyncReadbackBufferNLRS>(mGL, aSize, bufferHandle);
 }
+#endif
 
 NativeLayerCA::NativeLayerCA(const IntSize& aSize, bool aIsOpaque,
                              SurfacePoolHandleCA* aSurfacePoolHandle)
@@ -796,8 +835,9 @@ NativeLayerCA::NativeLayerCA(bool aIsOpaque)
       mIsOpaque(aIsOpaque) {
 #ifdef NIGHTLY_BUILD
   if (StaticPrefs::gfx_core_animation_specialize_video_log()) {
-    NSLog(@"VIDEO_LOG: NativeLayerCA: %p is being created to host an external "
-          @"image, which may force a video layer rebuild.",
+    NSLog(@"VIDEO_LOG: NativeLayerCA: %p is being created to host video, which "
+          @"will force a video "
+          @"layer rebuild.",
           this);
   }
 #endif
@@ -824,7 +864,7 @@ NativeLayerCA::~NativeLayerCA() {
   if (mHasEverAttachExternalImage &&
       StaticPrefs::gfx_core_animation_specialize_video_log()) {
     NSLog(@"VIDEO_LOG: ~NativeLayerCA: %p is being destroyed after hosting "
-          @"an external image.",
+          @"video.",
           this);
   }
 #endif
@@ -862,9 +902,6 @@ void NativeLayerCA::AttachExternalImage(wr::RenderTextureHost* aExternalImage) {
     return;
   }
 
-  // Determine if TextureHost is a video surface.
-  mIsTextureHostVideo = gfx::Info(mTextureHost->GetFormat())->isYuv;
-
   gfx::IntSize oldSize = mSize;
   mSize = texture->GetSize(0);
   bool changedSizeAndDisplayRect = (mSize != oldSize);
@@ -896,15 +933,18 @@ void NativeLayerCA::AttachExternalImage(wr::RenderTextureHost* aExternalImage) {
   });
 }
 
-bool NativeLayerCA::IsVideo(const MutexAutoLock& aProofOfLock) {
-  // If we have a texture host, we've checked to see if it's providing video.
-  // And if we don't have a texture host, it isn't video, so we just check
-  // the value we've computed.
-  return mIsTextureHostVideo;
+bool NativeLayerCA::IsVideo() {
+  // Anything with a texture host is considered a video source.
+  return mTextureHost;
+}
+
+bool NativeLayerCA::IsVideoAndLocked(const MutexAutoLock& aProofOfLock) {
+  // Anything with a texture host is considered a video source.
+  return mTextureHost;
 }
 
 bool NativeLayerCA::ShouldSpecializeVideo(const MutexAutoLock& aProofOfLock) {
-  if (!IsVideo(aProofOfLock)) {
+  if (!IsVideoAndLocked(aProofOfLock)) {
     // Only videos are eligible.
     return false;
   }
@@ -934,7 +974,49 @@ bool NativeLayerCA::ShouldSpecializeVideo(const MutexAutoLock& aProofOfLock) {
     return true;
   }
 
-  return StaticPrefs::gfx_core_animation_specialize_video();
+  // Beyond this point, we return true if-and-only-if we think we can achieve
+  // the power-saving "detached mode" of the macOS compositor.
+
+  if (!StaticPrefs::gfx_core_animation_specialize_video()) {
+    // Pref must be set.
+    return false;
+  }
+
+  if (pixelFormat != kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange &&
+      pixelFormat != kCVPixelFormatType_420YpCbCr8BiPlanarFullRange) {
+    // The video is not in one of the formats that qualifies for detachment.
+    return false;
+  }
+
+  // It will only detach if we're fullscreen.
+  return mRootWindowIsFullscreen;
+}
+
+void NativeLayerCA::SetRootWindowIsFullscreen(bool aFullscreen) {
+  if (mRootWindowIsFullscreen == aFullscreen) {
+    return;
+  }
+
+  MutexAutoLock lock(mMutex);
+
+  mRootWindowIsFullscreen = aFullscreen;
+
+  bool oldSpecializeVideo = mSpecializeVideo;
+  mSpecializeVideo = ShouldSpecializeVideo(lock);
+  bool changedSpecializeVideo = (mSpecializeVideo != oldSpecializeVideo);
+
+  if (changedSpecializeVideo) {
+#ifdef NIGHTLY_BUILD
+    if (StaticPrefs::gfx_core_animation_specialize_video_log()) {
+      NSLog(@"VIDEO_LOG: SetRootWindowIsFullscreen: %p is forcing a video "
+            @"layer rebuild.",
+            this);
+    }
+#endif
+
+    ForAllRepresentations(
+        [&](Representation& r) { r.mMutatedSpecializeVideo = true; });
+  }
 }
 
 void NativeLayerCA::SetSurfaceIsFlipped(bool aIsFlipped) {
@@ -1328,8 +1410,6 @@ void NativeLayerCA::NotifySurfaceReady() {
       mInProgressSurface,
       "NotifySurfaceReady called without preceding call to NextSurface");
 
-  mIsTextureHostVideo = false;
-
   if (mInProgressLockedIOSurface) {
     mInProgressLockedIOSurface->Unlock(false);
     mInProgressLockedIOSurface = nullptr;
@@ -1385,7 +1465,7 @@ void NativeLayerCA::ForAllRepresentations(F aFn) {
 NativeLayerCA::UpdateType NativeLayerCA::HasUpdate(
     WhichRepresentation aRepresentation) {
   MutexAutoLock lock(mMutex);
-  return GetRepresentation(aRepresentation).HasUpdate(IsVideo(lock));
+  return GetRepresentation(aRepresentation).HasUpdate(IsVideoAndLocked(lock));
 }
 
 /* static */
@@ -1430,7 +1510,7 @@ bool NativeLayerCA::ApplyChanges(WhichRepresentation aRepresentation,
       .ApplyChanges(aUpdate, mSize, mIsOpaque, mPosition, mTransform,
                     mDisplayRect, mClipRect, mBackingScale, mSurfaceIsFlipped,
                     mSamplingFilter, mSpecializeVideo, surface, mColor, mIsDRM,
-                    IsVideo(lock));
+                    IsVideo());
 }
 
 CALayer* NativeLayerCA::UnderlyingCALayer(WhichRepresentation aRepresentation) {
@@ -1457,8 +1537,10 @@ static NSString* NSStringForOSType(OSType type) {
   CFRelease(surfaceValues);
 
   if (aBuffer) {
+#ifdef XP_MACOSX
     CGColorSpaceRef colorSpace = CVImageBufferGetColorSpace(aBuffer);
     NSLog(@"ColorSpace is %@.\n", colorSpace);
+#endif
 
     CFDictionaryRef bufferAttachments =
         CVBufferGetAttachments(aBuffer, kCVAttachmentMode_ShouldPropagate);
@@ -1512,7 +1594,7 @@ bool NativeLayerCA::Representation::EnqueueSurface(IOSurfaceRef aSurfaceRef) {
     return false;
   }
 
-#ifdef NIGHTLY_BUILD
+#if defined(NIGHTLY_BUILD) && defined(XP_MACOSX)
   if (StaticPrefs::gfx_core_animation_specialize_video_check_color_space()) {
     // Ensure the resulting pixel buffer has a color space. If it doesn't, then
     // modify the surface and create the buffer again.
@@ -1764,10 +1846,10 @@ bool NativeLayerCA::Representation::ApplyChanges(
     mOpaquenessTintLayer.contentsGravity = kCAGravityTopLeft;
     if (aIsOpaque) {
       mOpaquenessTintLayer.backgroundColor =
-          [[[NSColor greenColor] colorWithAlphaComponent:0.5] CGColor];
+          CGColorCreateGenericRGB(0, 1, 0, 0.5);
     } else {
       mOpaquenessTintLayer.backgroundColor =
-          [[[NSColor redColor] colorWithAlphaComponent:0.5] CGColor];
+          CGColorCreateGenericRGB(1, 0, 0, 0.5);
     }
     [mWrappingCALayer addSublayer:mOpaquenessTintLayer];
   } else if (!shouldTintOpaqueness && mOpaquenessTintLayer) {
diff --git a/gfx/layers/PersistentBufferProvider.cpp b/gfx/layers/PersistentBufferProvider.cpp
index 0e02501a4a..d79c8cdca1 100644
--- a/gfx/layers/PersistentBufferProvider.cpp
+++ b/gfx/layers/PersistentBufferProvider.cpp
@@ -663,14 +663,15 @@ PersistentBufferProviderShared::BorrowSnapshot(gfx::DrawTarget* aTarget) {
 
   if (mDrawTarget) {
     auto back = GetTexture(mBack);
-    MOZ_ASSERT(back && back->IsLocked());
+    if (NS_WARN_IF(!back) || NS_WARN_IF(!back->IsLocked())) {
+      return nullptr;
+    }
     mSnapshot = back->BorrowSnapshot();
     return do_AddRef(mSnapshot);
   }
 
   auto front = GetTexture(mFront);
-  if (!front || front->IsLocked()) {
-    MOZ_ASSERT(false);
+  if (NS_WARN_IF(!front) || NS_WARN_IF(front->IsLocked())) {
     return nullptr;
   }
 
diff --git a/gfx/layers/RemoteTextureMap.cpp b/gfx/layers/RemoteTextureMap.cpp
index fa0cfd33f5..3fe3b13deb 100644
--- a/gfx/layers/RemoteTextureMap.cpp
+++ b/gfx/layers/RemoteTextureMap.cpp
@@ -369,7 +369,11 @@ void RemoteTextureMap::PushTexture(
         aTextureId, aTextureHost, std::move(aTextureData),
         std::move(aResourceWrapper));
 
-    MOZ_ASSERT(owner->mLatestTextureId < aTextureId);
+    MOZ_ASSERT(owner->mLatestPushedTextureId < aTextureId);
+    if (owner->mLatestPushedTextureId < aTextureId) {
+      owner->mLatestPushedTextureId = aTextureId;
+    }
+    MOZ_ASSERT(owner->mLatestUsingTextureId < aTextureId);
 
     owner->mWaitingTextureDataHolders.push_back(std::move(textureData));
 
@@ -898,9 +902,9 @@ void RemoteTextureMap::UpdateTexture(const MonitorAutoLock& aProofOfLock,
                                      const RemoteTextureId aTextureId) {
   MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
   MOZ_ASSERT(aOwner);
-  MOZ_ASSERT(aTextureId >= aOwner->mLatestTextureId);
+  MOZ_ASSERT(aTextureId >= aOwner->mLatestUsingTextureId);
 
-  if (aTextureId == aOwner->mLatestTextureId) {
+  if (aTextureId == aOwner->mLatestUsingTextureId) {
     // No need to update texture.
     return;
   }
@@ -913,7 +917,7 @@ void RemoteTextureMap::UpdateTexture(const MonitorAutoLock& aProofOfLock,
     }
     MOZ_RELEASE_ASSERT(front->mTextureHost);
     aOwner->mLatestTextureHost = front->mTextureHost;
-    aOwner->mLatestTextureId = front->mTextureId;
+    aOwner->mLatestUsingTextureId = front->mTextureId;
 
     UniquePtr<TextureDataHolder> holder = std::move(front);
     aOwner->mWaitingTextureDataHolders.pop_front();
@@ -962,10 +966,42 @@ void RemoteTextureMap::GetAllRenderingReadyCallbacks(
   MOZ_ASSERT(aOwner->mRenderingReadyCallbackHolders.empty());
 }
 
+bool RemoteTextureMap::WaitForRemoteTextureOwner(
+    RemoteTextureHostWrapper* aTextureHostWrapper) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  MOZ_ASSERT(aTextureHostWrapper);
+
+  const auto& ownerId = aTextureHostWrapper->mOwnerId;
+  const auto& forPid = aTextureHostWrapper->mForPid;
+
+  MonitorAutoLock lock(mMonitor);
+
+  auto* owner = GetTextureOwner(lock, ownerId, forPid);
+  // If there is no texture owner yet, then we might need to wait for one to
+  // be created, if allowed. If so, we must also wait for an initial texture
+  // host to be created so we can use it.
+  if (!owner || (!owner->mLatestTextureHost &&
+                 owner->mWaitingTextureDataHolders.empty())) {
+    const TimeDuration timeout = TimeDuration::FromMilliseconds(10000);
+    while (!owner || (!owner->mLatestTextureHost &&
+                      owner->mWaitingTextureDataHolders.empty())) {
+      if (owner && (owner->mIsContextLost || owner->mDeferUnregister)) {
+        // If the context was lost, no further updates are expected.
+        return false;
+      }
+      CVStatus status = mMonitor.Wait(timeout);
+      if (status == CVStatus::Timeout) {
+        return false;
+      }
+      owner = GetTextureOwner(lock, ownerId, forPid);
+    }
+  }
+  return true;
+}
+
 bool RemoteTextureMap::GetRemoteTexture(
     RemoteTextureHostWrapper* aTextureHostWrapper,
-    std::function<void(const RemoteTextureInfo&)>&& aReadyCallback,
-    bool aWaitForRemoteTextureOwner) {
+    std::function<void(const RemoteTextureInfo&)>&& aReadyCallback) {
   MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
   MOZ_ASSERT(aTextureHostWrapper);
 
@@ -983,27 +1019,8 @@ bool RemoteTextureMap::GetRemoteTexture(
     MonitorAutoLock lock(mMonitor);
 
     auto* owner = GetTextureOwner(lock, ownerId, forPid);
-    // If there is no texture owner yet, then we might need to wait for one to
-    // be created, if allowed. If so, we must also wait for an initial texture
-    // host to be created so we can use it.
-    if (!owner || (aWaitForRemoteTextureOwner && !owner->mLatestTextureHost &&
-                   owner->mWaitingTextureDataHolders.empty())) {
-      if (!aWaitForRemoteTextureOwner) {
-        return false;
-      }
-      const TimeDuration timeout = TimeDuration::FromMilliseconds(10000);
-      while (!owner || (!owner->mLatestTextureHost &&
-                        owner->mWaitingTextureDataHolders.empty())) {
-        if (owner && (owner->mIsContextLost || owner->mDeferUnregister)) {
-          // If the context was lost, no further updates are expected.
-          return false;
-        }
-        CVStatus status = mMonitor.Wait(timeout);
-        if (status == CVStatus::Timeout) {
-          return false;
-        }
-        owner = GetTextureOwner(lock, ownerId, forPid);
-      }
+    if (!owner) {
+      return false;
     }
 
     UpdateTexture(lock, owner, textureId);
@@ -1014,7 +1031,7 @@ bool RemoteTextureMap::GetRemoteTexture(
       return false;
     }
 
-    if (textureId == owner->mLatestTextureId) {
+    if (textureId == owner->mLatestUsingTextureId) {
       MOZ_ASSERT(owner->mLatestTextureHost);
       MOZ_ASSERT(owner->mLatestTextureHost->GetSize() == size);
       if (owner->mLatestTextureHost->GetSize() != size) {
@@ -1034,7 +1051,7 @@ bool RemoteTextureMap::GetRemoteTexture(
     }
 
     // Update mRemoteTextureHost
-    if (textureId == owner->mLatestTextureId) {
+    if (textureId == owner->mLatestUsingTextureId) {
       const auto key = std::pair(forPid, textureId);
       auto it = mRemoteTextureHostWrapperHolders.find(key);
       if (it != mRemoteTextureHostWrapperHolders.end() &&
@@ -1195,16 +1212,9 @@ bool RemoteTextureMap::CheckRemoteTextureReady(
     return true;
   }
 
-  if (it->second->mRemoteTextureHost) {
+  if (owner->mLatestPushedTextureId >= aInfo.mTextureId) {
     return true;
   }
-  MOZ_ASSERT(!it->second->mRemoteTextureHost);
-
-  // Check if RemoteTextureId is as expected.
-  if (!owner->mRenderingReadyCallbackHolders.empty()) {
-    auto& front = owner->mRenderingReadyCallbackHolders.front();
-    MOZ_RELEASE_ASSERT(aInfo.mTextureId >= front->mTextureId);
-  }
 
   auto callbackHolder = MakeUnique<RenderingReadyCallbackHolder>(
       aInfo.mTextureId, std::move(aCallback));
@@ -1234,9 +1244,8 @@ bool RemoteTextureMap::WaitRemoteTextureReady(const RemoteTextureInfo& aInfo) {
   }
 
   const TimeDuration timeout = TimeDuration::FromMilliseconds(1000);
-  TextureHost* remoteTexture = it->second->mRemoteTextureHost;
 
-  while (!remoteTexture) {
+  while (owner->mLatestPushedTextureId < aInfo.mTextureId) {
     CVStatus status = mMonitor.Wait(timeout);
     if (status == CVStatus::Timeout) {
       MOZ_ASSERT_UNREACHABLE("unexpected to be called");
@@ -1251,14 +1260,11 @@ bool RemoteTextureMap::WaitRemoteTextureReady(const RemoteTextureInfo& aInfo) {
       return false;
     }
 
-    remoteTexture = it->second->mRemoteTextureHost;
-    if (!remoteTexture) {
-      auto* owner = GetTextureOwner(lock, aInfo.mOwnerId, aInfo.mForPid);
-      // When owner is alreay unregistered, remote texture will not be pushed.
-      if (!owner || owner->mIsContextLost) {
-        // This could happen with IPC abnormal shutdown
-        return false;
-      }
+    auto* owner = GetTextureOwner(lock, aInfo.mOwnerId, aInfo.mForPid);
+    // When owner is alreay unregistered, remote texture will not be pushed.
+    if (!owner || owner->mIsContextLost) {
+      // This could happen with IPC abnormal shutdown
+      return false;
     }
   }
 
diff --git a/gfx/layers/RemoteTextureMap.h b/gfx/layers/RemoteTextureMap.h
index a60bfd4c3c..8aee1c6f7d 100644
--- a/gfx/layers/RemoteTextureMap.h
+++ b/gfx/layers/RemoteTextureMap.h
@@ -304,13 +304,14 @@ class RemoteTextureMap {
   void NotifyContextRestored(const RemoteTextureOwnerIdSet& aOwnerIds,
                              const base::ProcessId aForPid);
 
+  bool WaitForRemoteTextureOwner(RemoteTextureHostWrapper* aTextureHostWrapper);
+
   // Get remote texture's TextureHost for RemoteTextureHostWrapper.
   //
   // return true when aReadyCallback will be called.
   bool GetRemoteTexture(
       RemoteTextureHostWrapper* aTextureHostWrapper,
-      std::function<void(const RemoteTextureInfo&)>&& aReadyCallback,
-      bool aWaitForRemoteTextureOwner = false);
+      std::function<void(const RemoteTextureInfo&)>&& aReadyCallback);
 
   bool WaitForTxn(const RemoteTextureOwnerId aOwnerId,
                   const base::ProcessId aForPid, RemoteTextureTxnType aTxnType,
@@ -403,7 +404,8 @@ class RemoteTextureMap {
     std::deque<UniquePtr<RenderingReadyCallbackHolder>>
         mRenderingReadyCallbackHolders;
 
-    RemoteTextureId mLatestTextureId = {0};
+    RemoteTextureId mLatestPushedTextureId = {0};
+    RemoteTextureId mLatestUsingTextureId = {0};
     CompositableTextureHostRef mLatestTextureHost;
     CompositableTextureHostRef mLatestRenderedTextureHost;
     // Holds compositable refs to TextureHosts of RenderTextureHosts that are
diff --git a/gfx/layers/SurfacePool.h b/gfx/layers/SurfacePool.h
index eecb398d85..6be3718af5 100644
--- a/gfx/layers/SurfacePool.h
+++ b/gfx/layers/SurfacePool.h
@@ -31,7 +31,7 @@ class SurfacePool {
  public:
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SurfacePool);
 
-#if defined(XP_MACOSX) || defined(MOZ_WAYLAND)
+#if defined(XP_DARWIN) || defined(MOZ_WAYLAND)
   static RefPtr<SurfacePool> Create(size_t aPoolSizeLimit);
 #endif
 
diff --git a/gfx/layers/SurfacePoolCA.h b/gfx/layers/SurfacePoolCA.h
index 97344f7d06..265782df9e 100644
--- a/gfx/layers/SurfacePoolCA.h
+++ b/gfx/layers/SurfacePoolCA.h
@@ -6,7 +6,7 @@
 #ifndef mozilla_layers_SurfacePoolCA_h
 #define mozilla_layers_SurfacePoolCA_h
 
-#include <IOSurface/IOSurface.h>
+#include <IOSurface/IOSurfaceRef.h>
 
 #include <deque>
 #include <unordered_map>
diff --git a/gfx/layers/SurfacePoolCA.mm b/gfx/layers/SurfacePoolCA.mm
index 47b2663ed7..4e012350f0 100644
--- a/gfx/layers/SurfacePoolCA.mm
+++ b/gfx/layers/SurfacePoolCA.mm
@@ -6,6 +6,7 @@
 #include "mozilla/layers/SurfacePoolCA.h"
 
 #import <CoreVideo/CVPixelBuffer.h>
+#include <IOSurface/IOSurfaceTypes.h>
 
 #include <algorithm>
 #include <unordered_set>
@@ -16,7 +17,12 @@
 #include "mozilla/StaticMutex.h"
 #include "mozilla/StaticPrefs_gfx.h"
 
-#include "GLContextCGL.h"
+#ifdef XP_MACOSX
+#  include "GLContextCGL.h"
+#else
+#  include "GLContextEAGL.h"
+#endif
+
 #include "MozFramebuffer.h"
 #include "ScopedGLHelpers.h"
 
@@ -28,7 +34,11 @@ using gfx::IntRect;
 using gfx::IntRegion;
 using gfx::IntSize;
 using gl::GLContext;
+#ifdef XP_MACOSX
 using gl::GLContextCGL;
+#else
+using gl::GLContextEAGL;
+#endif
 
 /* static */ RefPtr<SurfacePool> SurfacePool::Create(size_t aPoolSizeLimit) {
   return new SurfacePoolCA(aPoolSizeLimit);
@@ -306,8 +316,13 @@ Maybe<GLuint> SurfacePoolCA::LockedPool::GetFramebufferForSurface(
       "Framebuffer creation", GRAPHICS_TileAllocation,
       nsPrintfCString("%dx%d", entry.mSize.width, entry.mSize.height));
 
+#ifdef XP_MACOSX
   RefPtr<GLContextCGL> cgl = GLContextCGL::Cast(aGL);
   MOZ_RELEASE_ASSERT(cgl, "Unexpected GLContext type");
+#else
+  RefPtr<GLContextEAGL> eagl = GLContextEAGL::Cast(aGL);
+  MOZ_RELEASE_ASSERT(eagl, "Unexpected GLContext type");
+#endif
 
   if (!aGL->MakeCurrent()) {
     // Context may have been destroyed.
@@ -318,10 +333,14 @@ Maybe<GLuint> SurfacePoolCA::LockedPool::GetFramebufferForSurface(
   {
     const gl::ScopedBindTexture bindTex(aGL, tex,
                                         LOCAL_GL_TEXTURE_RECTANGLE_ARB);
+#ifdef XP_MACOSX
     CGLTexImageIOSurface2D(cgl->GetCGLContext(), LOCAL_GL_TEXTURE_RECTANGLE_ARB,
                            LOCAL_GL_RGBA, entry.mSize.width, entry.mSize.height,
                            LOCAL_GL_BGRA, LOCAL_GL_UNSIGNED_INT_8_8_8_8_REV,
                            entry.mIOSurface.get(), 0);
+#else
+    MOZ_CRASH("unimplemented");
+#endif
   }
 
   auto fb =
diff --git a/gfx/layers/apz/src/APZCTreeManager.cpp b/gfx/layers/apz/src/APZCTreeManager.cpp
index d28392b716..ef3cde3596 100644
--- a/gfx/layers/apz/src/APZCTreeManager.cpp
+++ b/gfx/layers/apz/src/APZCTreeManager.cpp
@@ -62,6 +62,8 @@
 mozilla::LazyLogModule mozilla::layers::APZCTreeManager::sLog("apz.manager");
 #define APZCTM_LOG(...) \
   MOZ_LOG(APZCTreeManager::sLog, LogLevel::Debug, (__VA_ARGS__))
+#define APZCTM_LOGV(...) \
+  MOZ_LOG(APZCTreeManager::sLog, LogLevel::Verbose, (__VA_ARGS__))
 
 static mozilla::LazyLogModule sApzKeyLog("apz.key");
 #define APZ_KEY_LOG(...) MOZ_LOG(sApzKeyLog, LogLevel::Debug, (__VA_ARGS__))
@@ -83,10 +85,10 @@ typedef CompositorBridgeParent::LayerTreeState LayerTreeState;
 struct APZCTreeManager::TreeBuildingState {
   TreeBuildingState(LayersId aRootLayersId, bool aIsFirstPaint,
                     LayersId aOriginatingLayersId, APZTestData* aTestData,
-                    uint32_t aPaintSequence)
+                    uint32_t aPaintSequence, bool aIsTestLoggingEnabled)
       : mIsFirstPaint(aIsFirstPaint),
         mOriginatingLayersId(aOriginatingLayersId),
-        mPaintLogger(aTestData, aPaintSequence) {
+        mPaintLogger(aTestData, aPaintSequence, aIsTestLoggingEnabled) {
     CompositorBridgeParent::CallWithIndirectShadowTree(
         aRootLayersId, [this](LayerTreeState& aState) -> void {
           mCompositorController = aState.GetCompositorController();
@@ -158,6 +160,9 @@ struct APZCTreeManager::TreeBuildingState {
   // cumulative EventRegionsOverride flags from the reflayers, and is used to
   // apply them to descendant layers.
   std::stack<EventRegionsOverride> mOverrideFlags;
+
+  // Wether the APZC correspoinding to the originating LayersId was updated.
+  bool mOriginatingLayersIdUpdated = false;
 };
 
 class APZCTreeManager::CheckerboardFlushObserver : public nsIObserver {
@@ -391,8 +396,7 @@ void APZCTreeManager::SetAllowedTouchBehavior(
     uint64_t aInputBlockId, const nsTArray<TouchBehaviorFlags>& aValues) {
   if (!APZThreadUtils::IsControllerThread()) {
     APZThreadUtils::RunOnControllerThread(
-        NewRunnableMethod<uint64_t,
-                          StoreCopyPassByLRef<nsTArray<TouchBehaviorFlags>>>(
+        NewRunnableMethod<uint64_t, nsTArray<TouchBehaviorFlags>>(
             "layers::APZCTreeManager::SetAllowedTouchBehavior", this,
             &APZCTreeManager::SetAllowedTouchBehavior, aInputBlockId,
             aValues.Clone()));
@@ -420,9 +424,11 @@ void APZCTreeManager::SetBrowserGestureResponse(
   mInputQueue->SetBrowserGestureResponse(aInputBlockId, aResponse);
 }
 
-void APZCTreeManager::UpdateHitTestingTree(
-    const WebRenderScrollDataWrapper& aRoot, bool aIsFirstPaint,
-    LayersId aOriginatingLayersId, uint32_t aPaintSequenceNumber) {
+APZCTreeManager::OriginatingLayersIdUpdated
+APZCTreeManager::UpdateHitTestingTree(const WebRenderScrollDataWrapper& aRoot,
+                                      bool aIsFirstPaint,
+                                      LayersId aOriginatingLayersId,
+                                      uint32_t aPaintSequenceNumber) {
   AssertOnUpdaterThread();
 
   RecursiveMutexAutoLock lock(mTreeLock);
@@ -430,7 +436,8 @@ void APZCTreeManager::UpdateHitTestingTree(
   // For testing purposes, we log some data to the APZTestData associated with
   // the layers id that originated this update.
   APZTestData* testData = nullptr;
-  if (StaticPrefs::apz_test_logging_enabled()) {
+  const bool testLoggingEnabled = StaticPrefs::apz_test_logging_enabled();
+  if (testLoggingEnabled) {
     MutexAutoLock lock(mTestDataLock);
     UniquePtr<APZTestData> ptr = MakeUnique<APZTestData>();
     auto result =
@@ -440,7 +447,7 @@ void APZCTreeManager::UpdateHitTestingTree(
   }
 
   TreeBuildingState state(mRootLayersId, aIsFirstPaint, aOriginatingLayersId,
-                          testData, aPaintSequenceNumber);
+                          testData, aPaintSequenceNumber, testLoggingEnabled);
 
   // We do this business with collecting the entire tree into an array because
   // otherwise it's very hard to determine which APZC instances need to be
@@ -730,6 +737,8 @@ void APZCTreeManager::UpdateHitTestingTree(
     mRootNode->Dump("  ");
   }
   SendSubtreeTransformsToChromeMainThread(nullptr);
+
+  return OriginatingLayersIdUpdated{state.mOriginatingLayersIdUpdated};
 }
 
 void APZCTreeManager::UpdateFocusState(LayersId aRootLayerTreeId,
@@ -763,7 +772,7 @@ void APZCTreeManager::SampleForWebRender(const Maybe<VsyncId>& aVsyncId,
     controller->ScheduleRenderOnCompositorThread(
         wr::RenderReasons::ANIMATED_PROPERTY);
   }
-  APZCTM_LOG(
+  APZCTM_LOGV(
       "APZCTreeManager(%p)::SampleForWebRender, want more composites: %d\n",
       this, (activeAnimations && controller));
 
@@ -1231,6 +1240,10 @@ HitTestingTreeNode* APZCTreeManager::PrepareNodeForLayer(
       "Found APZC %p for layer %p with identifiers %" PRIx64 " %" PRId64 "\n",
       apzc.get(), aLayer.GetLayer(), uint64_t(guid.mLayersId), guid.mScrollId);
 
+  if (aLayersId == aState.mOriginatingLayersId) {
+    aState.mOriginatingLayersIdUpdated = true;
+  }
+
   // If we haven't encountered a layer already with the same metrics, then we
   // need to do the full reuse-or-make-an-APZC algorithm, which is contained
   // inside the block below.
@@ -1522,6 +1535,11 @@ APZEventResult APZCTreeManager::ReceiveInputEvent(
     }
     case MOUSE_INPUT: {
       MouseInput& mouseInput = aEvent.AsMouseInput();
+      MOZ_LOG(APZCTreeManager::sLog,
+              mouseInput.mType == MouseInput::MOUSE_MOVE ? LogLevel::Verbose
+                                                         : LogLevel::Debug,
+              ("Received mouse input type %d at %s\n", (int)mouseInput.mType,
+               ToString(mouseInput.mOrigin).c_str()));
       mouseInput.mHandledByAPZ = true;
 
       SetCurrentMousePosition(mouseInput.mOrigin);
@@ -1613,6 +1631,9 @@ APZEventResult APZCTreeManager::ReceiveInputEvent(
 
       // Do this before early return for Fission hit testing.
       ScrollWheelInput& wheelInput = aEvent.AsScrollWheelInput();
+      APZCTM_LOG("Received wheel input at %s with delta (%f, %f)\n",
+                 ToString(wheelInput.mOrigin).c_str(), wheelInput.mDeltaX,
+                 wheelInput.mDeltaY);
       state.mHit = GetTargetAPZC(wheelInput.mOrigin);
 
       wheelInput.mHandledByAPZ = WillHandleInput(wheelInput);
@@ -1674,6 +1695,9 @@ APZEventResult APZCTreeManager::ReceiveInputEvent(
 
       // Do this before early return for Fission hit testing.
       PanGestureInput& panInput = aEvent.AsPanGestureInput();
+      APZCTM_LOG("Received pan gesture input type %d at %s with delta %s\n",
+                 (int)panInput.mType, ToString(panInput.mPanStartPoint).c_str(),
+                 ToString(panInput.mPanDisplacement).c_str());
       state.mHit = GetTargetAPZC(panInput.mPanStartPoint);
 
       panInput.mHandledByAPZ = WillHandleInput(panInput);
@@ -2021,6 +2045,18 @@ APZEventResult APZCTreeManager::InputHandlingState::Finish(
 
 void APZCTreeManager::ProcessTouchInput(InputHandlingState& aState,
                                         MultiTouchInput& aInput) {
+  APZCTM_LOG("Received touch input type %d with touch points [%s]\n",
+             (int)aInput.mType,
+             [&] {
+               nsCString result;
+               for (const auto& touch : aInput.mTouches) {
+                 result.AppendPrintf("%s",
+                                     ToString(touch.mScreenPoint).c_str());
+               }
+               return result;
+             }()
+                 .get());
+
   aInput.mHandledByAPZ = true;
   nsTArray<TouchBehaviorFlags> touchBehaviors;
   HitTestingTreeNodeAutoLock hitScrollbarNode;
diff --git a/gfx/layers/apz/src/APZCTreeManager.h b/gfx/layers/apz/src/APZCTreeManager.h
index ff9bba51ca..71d35fd5a6 100644
--- a/gfx/layers/apz/src/APZCTreeManager.h
+++ b/gfx/layers/apz/src/APZCTreeManager.h
@@ -190,10 +190,13 @@ class APZCTreeManager : public IAPZCTreeManager, public APZInputBridge {
    *                             this layer update. Note that every child
    *                             process' layer subtree has its own sequence
    *                             numbers.
+   * @return OriginatingLayersIdUpdated whether the given
+   * |aOriginatingLayersId|'s data was processed.
    */
-  void UpdateHitTestingTree(const WebRenderScrollDataWrapper& aRoot,
-                            bool aIsFirstPaint, LayersId aOriginatingLayersId,
-                            uint32_t aPaintSequenceNumber);
+  enum class OriginatingLayersIdUpdated : bool { No, Yes };
+  OriginatingLayersIdUpdated UpdateHitTestingTree(
+      const WebRenderScrollDataWrapper& aRoot, bool aIsFirstPaint,
+      LayersId aOriginatingLayersId, uint32_t aPaintSequenceNumber);
 
   /**
    * Called when webrender is enabled, from the sampler thread. This function
diff --git a/gfx/layers/apz/src/APZUpdater.cpp b/gfx/layers/apz/src/APZUpdater.cpp
index 2bbad6e1a7..2f1b551f3a 100644
--- a/gfx/layers/apz/src/APZUpdater.cpp
+++ b/gfx/layers/apz/src/APZUpdater.cpp
@@ -191,14 +191,38 @@ void APZUpdater::UpdateScrollDataAndTreeState(
             auto isFirstPaint = aScrollData.IsFirstPaint();
             auto paintSequenceNumber = aScrollData.GetPaintSequenceNumber();
 
+            auto previous = self->mScrollData.find(aOriginatingLayersId);
+            // If there's the previous scroll data which hasn't yet been
+            // processed, we need to merge the previous scroll position updates
+            // into the latest one.
+            if (previous != self->mScrollData.end()) {
+              WebRenderScrollData& previousData = previous->second;
+              if (previousData.GetWasUpdateSkipped()) {
+                MOZ_ASSERT(previousData.IsFirstPaint());
+                aScrollData.PrependUpdates(previousData);
+              }
+            }
+
             self->mScrollData[aOriginatingLayersId] = std::move(aScrollData);
             auto root = self->mScrollData.find(aRootLayerTreeId);
             if (root == self->mScrollData.end()) {
               return;
             }
-            self->mApz->UpdateHitTestingTree(
-                WebRenderScrollDataWrapper(*self, &(root->second)),
-                isFirstPaint, aOriginatingLayersId, paintSequenceNumber);
+            if ((self->mApz->UpdateHitTestingTree(
+                     WebRenderScrollDataWrapper(*self, &(root->second)),
+                     isFirstPaint, aOriginatingLayersId, paintSequenceNumber) ==
+                 APZCTreeManager::OriginatingLayersIdUpdated::No) &&
+                isFirstPaint) {
+              // If the given |aOriginatingLayersId| data wasn't used for
+              // updating, it's likly that the parent process hasn't yet
+              // received the LayersId as "ReferentId", thus we need to process
+              // it in a subsequent update where we got the "ReferentId".
+              //
+              // NOTE: We restrict the above previous scroll data prepending to
+              // the first paint case, otherwise the cumulative scroll data may
+              // be exploded if we have never received the "ReferenceId".
+              self->mScrollData[aOriginatingLayersId].SetWasUpdateSkipped();
+            }
           }));
 }
 
diff --git a/gfx/layers/apz/src/AsyncPanZoomController.cpp b/gfx/layers/apz/src/AsyncPanZoomController.cpp
index 342375c019..edbd2ecffa 100644
--- a/gfx/layers/apz/src/AsyncPanZoomController.cpp
+++ b/gfx/layers/apz/src/AsyncPanZoomController.cpp
@@ -106,6 +106,10 @@ static mozilla::LazyLogModule sApzCtlLog("apz.controller");
   APZC_LOG("%p(%s scrollId=%" PRIu64 "): " fmt, (apzc),   \
            (apzc)->IsRootContent() ? "root" : "subframe", \
            (apzc)->GetScrollId(), ##__VA_ARGS__)
+#define APZC_LOGV_DETAIL(fmt, apzc, ...)                   \
+  APZC_LOGV("%p(%s scrollId=%" PRIu64 "): " fmt, (apzc),   \
+            (apzc)->IsRootContent() ? "root" : "subframe", \
+            (apzc)->GetScrollId(), ##__VA_ARGS__)
 
 #define APZC_LOG_FM_COMMON(fm, prefix, level, ...)                 \
   if (MOZ_LOG_TEST(sApzCtlLog, level)) {                           \
@@ -2248,6 +2252,11 @@ CSSRect AsyncPanZoomController::GetCurrentScrollRangeInCssPixels() const {
   return Metrics().CalculateScrollRange();
 }
 
+bool AsyncPanZoomController::AllowOneTouchPinch() const {
+  return StaticPrefs::apz_one_touch_pinch_enabled() &&
+         ZoomConstraintsAllowZoom();
+}
+
 // Return whether or not the underlying layer can be scrolled on either axis.
 bool AsyncPanZoomController::CanScroll(const InputData& aEvent) const {
   ParentLayerPoint delta = GetDeltaForEvent(aEvent);
@@ -4734,7 +4743,7 @@ bool AsyncPanZoomController::UpdateAnimation(
   // Even if there's no animation, if we have a scroll offset change pending due
   // to the frame delay, we need to keep compositing.
   if (mLastSampleTime == aSampleTime) {
-    APZC_LOG_DETAIL(
+    APZC_LOGV_DETAIL(
         "UpdateAnimation short-circuit, animation=%p, pending frame-delayed "
         "offset=%d\n",
         this, mAnimation.get(), HavePendingFrameDelayedOffset());
@@ -4754,8 +4763,8 @@ bool AsyncPanZoomController::UpdateAnimation(
   // so that e.g. a main-thread animation can stay in sync with user-driven
   // scrolling or a compositor animation.
   bool needComposite = SampleCompositedAsyncTransform(aProofOfLock);
-  APZC_LOG_DETAIL("UpdateAnimation needComposite=%d mAnimation=%p\n", this,
-                  needComposite, mAnimation.get());
+  APZC_LOGV_DETAIL("UpdateAnimation needComposite=%d mAnimation=%p\n", this,
+                   needComposite, mAnimation.get());
 
   TimeDuration sampleTimeDelta = aSampleTime - mLastSampleTime;
   mLastSampleTime = aSampleTime;
@@ -5581,17 +5590,6 @@ void AsyncPanZoomController::NotifyLayersUpdated(
         aScrollMetadata.GetOverscrollBehavior());
   }
 
-  if (needToReclampScroll) {
-    // Whenever scrollable rect or composition bounds has changed, we need to
-    // re-clamp the scroll offset since it may be out of bounds. Also note that
-    // we need to re-clamp before updating new scroll offsets from content since
-    // we will use the last scroll offset to reflect the new offsets.
-    ClampAndSetVisualScrollOffset(Metrics().GetVisualScrollOffset());
-    for (auto& sampledState : mSampledState) {
-      sampledState.ClampVisualScrollOffset(Metrics());
-    }
-  }
-
   bool instantScrollMayTriggerTransform = false;
   bool scrollOffsetUpdated = false;
   bool smoothScrollRequested = false;
@@ -5738,20 +5736,11 @@ void AsyncPanZoomController::NotifyLayersUpdated(
       relativeDelta =
           Some(Metrics().ApplyPureRelativeScrollUpdateFrom(scrollUpdate));
       Metrics().RecalculateLayoutViewportOffset();
-    } else if (scrollUpdate.GetType() == ScrollUpdateType::MergeableAbsolute) {
-      APZC_LOG("%p mergeable updating scroll offset from %s to %s\n", this,
-               ToString(Metrics().GetVisualScrollOffset()).c_str(),
-               ToString(scrollUpdate.GetDestination()).c_str());
-      relativeDelta =
-          Some(Metrics().ApplyAbsoluteScrollUpdateFrom(scrollUpdate).second);
-      Metrics().RecalculateLayoutViewportOffset();
-      scrollOffsetUpdated = true;
     } else {
       APZC_LOG("%p updating scroll offset from %s to %s\n", this,
                ToString(Metrics().GetVisualScrollOffset()).c_str(),
                ToString(scrollUpdate.GetDestination()).c_str());
-      auto [offsetChanged, _] =
-          Metrics().ApplyAbsoluteScrollUpdateFrom(scrollUpdate);
+      bool offsetChanged = Metrics().ApplyScrollUpdateFrom(scrollUpdate);
       Metrics().RecalculateLayoutViewportOffset();
 
       if (offsetChanged || scrollUpdate.GetMode() != ScrollMode::Instant ||
@@ -5788,6 +5777,15 @@ void AsyncPanZoomController::NotifyLayersUpdated(
     }
   }
 
+  if (aIsFirstPaint || needToReclampScroll) {
+    // The scrollable rect or composition bounds may have changed in a way that
+    // makes our local scroll offset out of bounds, so clamp it.
+    ClampAndSetVisualScrollOffset(Metrics().GetVisualScrollOffset());
+    for (auto& sampledState : mSampledState) {
+      sampledState.ClampVisualScrollOffset(Metrics());
+    }
+  }
+
   if (scrollOffsetUpdated) {
     for (auto& sampledState : mSampledState) {
       if (!didCancelAnimation && cumulativeRelativeDelta.isSome()) {
diff --git a/gfx/layers/apz/src/AsyncPanZoomController.h b/gfx/layers/apz/src/AsyncPanZoomController.h
index fdc72b1971..d0c4537a66 100644
--- a/gfx/layers/apz/src/AsyncPanZoomController.h
+++ b/gfx/layers/apz/src/AsyncPanZoomController.h
@@ -1305,6 +1305,8 @@ class AsyncPanZoomController {
    */
   CSSRect GetCurrentScrollRangeInCssPixels() const;
 
+  bool AllowOneTouchPinch() const;
+
  private:
   /**
    * Advances to the next sample, if there is one, the list of sampled states
diff --git a/gfx/layers/apz/src/AutoscrollAnimation.cpp b/gfx/layers/apz/src/AutoscrollAnimation.cpp
index 8d4b8fca10..45063ef2b4 100644
--- a/gfx/layers/apz/src/AutoscrollAnimation.cpp
+++ b/gfx/layers/apz/src/AutoscrollAnimation.cpp
@@ -17,7 +17,7 @@ namespace mozilla {
 namespace layers {
 
 // Helper function for AutoscrollAnimation::DoSample().
-// Basically copied as-is from toolkit/actors/AutoScrollChild.jsm.
+// Basically copied as-is from toolkit/actors/AutoScrollChild.sys.mjs.
 static float Accelerate(ScreenCoord curr, ScreenCoord start) {
   static const int speed = 12;
   float val = (curr - start) / speed;
diff --git a/gfx/layers/apz/src/GenericScrollAnimation.cpp b/gfx/layers/apz/src/GenericScrollAnimation.cpp
index 04ca8c4697..62f19fab35 100644
--- a/gfx/layers/apz/src/GenericScrollAnimation.cpp
+++ b/gfx/layers/apz/src/GenericScrollAnimation.cpp
@@ -15,6 +15,9 @@
 #include "ScrollAnimationMSDPhysics.h"
 #include "mozilla/StaticPrefs_general.h"
 
+static mozilla::LazyLogModule sApzScrollAnimLog("apz.scrollanimation");
+#define GSA_LOG(...) MOZ_LOG(sApzScrollAnimLog, LogLevel::Debug, (__VA_ARGS__))
+
 namespace mozilla {
 namespace layers {
 
@@ -101,6 +104,12 @@ bool GenericScrollAnimation::DoSample(FrameMetrics& aFrameMetrics,
   // then end the animation early. Note that the initial displacement could be 0
   // if the compositor ran very quickly (<1ms) after the animation was created.
   // When that happens we want to make sure the animation continues.
+  GSA_LOG(
+      "Sampling GenericScrollAnimation: time %f finished %d sampledDest %s "
+      "adjustedOffset %s overscroll %s\n",
+      (now - TimeStamp::ProcessCreation()).ToMilliseconds(), finished,
+      ToString(CSSPoint::FromAppUnits(sampledDest)).c_str(),
+      ToString(adjustedOffset).c_str(), ToString(overscroll).c_str());
   if (!IsZero(displacement / zoom) && IsZero(adjustedOffset / zoom)) {
     // Nothing more to do - end the animation.
     return false;
diff --git a/gfx/layers/apz/src/GestureEventListener.cpp b/gfx/layers/apz/src/GestureEventListener.cpp
index b54674b593..4300e9ba41 100644
--- a/gfx/layers/apz/src/GestureEventListener.cpp
+++ b/gfx/layers/apz/src/GestureEventListener.cpp
@@ -5,13 +5,16 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "GestureEventListener.h"
-#include <algorithm>                 // for max
+#include <algorithm>  // for max
+#include <ostream>
 #include <math.h>                    // for fabsf
 #include <stddef.h>                  // for size_t
 #include "AsyncPanZoomController.h"  // for AsyncPanZoomController
 #include "InputBlockState.h"         // for TouchBlockState
 #include "base/task.h"               // for CancelableTask, etc
 #include "InputBlockState.h"         // for TouchBlockState
+#include "mozilla/Assertions.h"
+#include "mozilla/EventForwards.h"
 #include "mozilla/StaticPrefs_apz.h"
 #include "mozilla/StaticPrefs_ui.h"
 #include "nsDebug.h"      // for NS_WARNING
@@ -83,8 +86,8 @@ GestureEventListener::~GestureEventListener() = default;
 
 nsEventStatus GestureEventListener::HandleInputEvent(
     const MultiTouchInput& aEvent) {
-  GEL_LOG("Receiving event type %d with %zu touches in state %d\n",
-          aEvent.mType, aEvent.mTouches.Length(), mState);
+  GEL_LOG("Receiving event type %d with %zu touches in state %s\n",
+          aEvent.mType, aEvent.mTouches.Length(), ToString(mState).c_str());
 
   nsEventStatus rv = nsEventStatus_eIgnore;
 
@@ -175,16 +178,15 @@ nsEventStatus GestureEventListener::HandleInputTouchSingleStart() {
       EnterFirstSingleTouchDown();
       break;
     case GESTURE_FIRST_SINGLE_TOUCH_UP:
+      // Bail out of any gesture that includes the first tap.
+      CancelLongTapTimeoutTask();
+      CancelMaxTapTimeoutTask();
       if (SecondTapIsFar()) {
-        // If the second tap goes down far away from the first, then bail out
-        // of any gesture that includes the first tap.
-        CancelLongTapTimeoutTask();
-        CancelMaxTapTimeoutTask();
-        mSingleTapSent = Nothing();
-
-        // But still allow the second tap to participate in a gesture
+        // If the second tap goes down far away from the first,
+        // allow the second tap to participate in a gesture
         // (e.g. lead to a single tap, or a double tap if an additional
         // tap occurs near the same location).
+        mSingleTapSent = Nothing();
         EnterFirstSingleTouchDown();
       } else {
         // Otherwise, reset the touch start position so that, if this turns into
@@ -225,9 +227,10 @@ nsEventStatus GestureEventListener::HandleInputTouchMultiStart() {
       rv = nsEventStatus_eConsumeNoDefault;
       break;
     case GESTURE_FIRST_SINGLE_TOUCH_UP:
-    case GESTURE_SECOND_SINGLE_TOUCH_DOWN:
       // Cancel wait for double tap
       CancelMaxTapTimeoutTask();
+      [[fallthrough]];
+    case GESTURE_SECOND_SINGLE_TOUCH_DOWN:
       MOZ_ASSERT(mSingleTapSent.isSome());
       if (!mSingleTapSent.value()) {
         TriggerSingleTapConfirmedEvent();
@@ -307,12 +310,8 @@ nsEventStatus GestureEventListener::HandleInputTouchMove() {
       // If touch has moved noticeably (within StaticPrefs::apz_max_tap_time()),
       // change state.
       if (MoveDistanceIsLarge()) {
-        CancelLongTapTimeoutTask();
-        CancelMaxTapTimeoutTask();
         mSingleTapSent = Nothing();
-        if (!StaticPrefs::apz_one_touch_pinch_enabled()) {
-          // If the one-touch-pinch feature is disabled, bail out of the double-
-          // tap gesture instead.
+        if (!mAsyncPanZoomController->AllowOneTouchPinch()) {
           SetState(GESTURE_NONE);
           break;
         }
@@ -451,7 +450,6 @@ nsEventStatus GestureEventListener::HandleInputTouchEnd() {
     }
 
     case GESTURE_SECOND_SINGLE_TOUCH_DOWN: {
-      CancelMaxTapTimeoutTask();
       MOZ_ASSERT(mSingleTapSent.isSome());
       mAsyncPanZoomController->HandleGestureEvent(CreateTapEvent(
           mLastTouchInput, mSingleTapSent.value()
@@ -535,7 +533,9 @@ nsEventStatus GestureEventListener::HandleInputTouchCancel() {
 }
 
 void GestureEventListener::HandleInputTimeoutLongTap() {
-  GEL_LOG("Running long-tap timeout task in state %d\n", mState);
+  MOZ_ASSERT(mState != GESTURE_SECOND_SINGLE_TOUCH_DOWN);
+  GEL_LOG("Running long-tap timeout task in state %s\n",
+          ToString(mState).c_str());
 
   mLongTapTimeoutTask = nullptr;
 
@@ -559,14 +559,15 @@ void GestureEventListener::HandleInputTimeoutLongTap() {
 }
 
 void GestureEventListener::HandleInputTimeoutMaxTap(bool aDuringFastFling) {
-  GEL_LOG("Running max-tap timeout task in state %d\n", mState);
+  MOZ_ASSERT(mState != GESTURE_SECOND_SINGLE_TOUCH_DOWN);
+  GEL_LOG("Running max-tap timeout task in state %s\n",
+          ToString(mState).c_str());
 
   mMaxTapTimeoutTask = nullptr;
 
   if (mState == GESTURE_FIRST_SINGLE_TOUCH_DOWN) {
     SetState(GESTURE_FIRST_SINGLE_TOUCH_MAX_TAP_DOWN);
-  } else if (mState == GESTURE_FIRST_SINGLE_TOUCH_UP ||
-             mState == GESTURE_SECOND_SINGLE_TOUCH_DOWN) {
+  } else if (mState == GESTURE_FIRST_SINGLE_TOUCH_UP) {
     MOZ_ASSERT(mSingleTapSent.isSome());
     if (!aDuringFastFling && !mSingleTapSent.value()) {
       TriggerSingleTapConfirmedEvent();
@@ -585,6 +586,8 @@ void GestureEventListener::TriggerSingleTapConfirmedEvent() {
 }
 
 void GestureEventListener::SetState(GestureState aState) {
+  GEL_LOG("State change from %s to %s", ToString(mState).c_str(),
+          ToString(aState).c_str());
   mState = aState;
 
   if (mState == GESTURE_NONE) {
@@ -598,10 +601,7 @@ void GestureEventListener::SetState(GestureState aState) {
 }
 
 void GestureEventListener::CancelLongTapTimeoutTask() {
-  if (mState == GESTURE_SECOND_SINGLE_TOUCH_DOWN) {
-    // being in this state means the task has been canceled already
-    return;
-  }
+  MOZ_ASSERT(mState != GESTURE_SECOND_SINGLE_TOUCH_DOWN);
 
   if (mLongTapTimeoutTask) {
     mLongTapTimeoutTask->Cancel();
@@ -628,6 +628,8 @@ void GestureEventListener::CreateLongTapTimeoutTask() {
 }
 
 void GestureEventListener::CancelMaxTapTimeoutTask() {
+  MOZ_ASSERT(mState != GESTURE_SECOND_SINGLE_TOUCH_DOWN);
+
   if (mState == GESTURE_FIRST_SINGLE_TOUCH_MAX_TAP_DOWN) {
     // being in this state means the timer has just been triggered
     return;
@@ -659,5 +661,40 @@ void GestureEventListener::CreateMaxTapTimeoutTask() {
                                            std::max(0L, remainingDelay));
 }
 
+std::ostream& operator<<(std::ostream& os,
+                         GestureEventListener::GestureState aState) {
+  switch (aState) {
+    case GestureEventListener::GESTURE_NONE:
+      os << "GESTURE_NONE";
+      break;
+    case GestureEventListener::GESTURE_FIRST_SINGLE_TOUCH_DOWN:
+      os << "GESTURE_FIRST_SINGLE_TOUCH_DOWN";
+      break;
+    case GestureEventListener::GESTURE_FIRST_SINGLE_TOUCH_MAX_TAP_DOWN:
+      os << "GESTURE_FIRST_SINGLE_TOUCH_MAX_TAP_DOWN";
+      break;
+    case GestureEventListener::GESTURE_FIRST_SINGLE_TOUCH_UP:
+      os << "GESTURE_FIRST_SINGLE_TOUCH_UP";
+      break;
+    case GestureEventListener::GESTURE_SECOND_SINGLE_TOUCH_DOWN:
+      os << "GESTURE_SECOND_SINGLE_TOUCH_DOWN";
+      break;
+    case GestureEventListener::GESTURE_LONG_TOUCH_DOWN:
+      os << "GESTURE_LONG_TOUCH_DOWN";
+      break;
+    case GestureEventListener::GESTURE_MULTI_TOUCH_DOWN:
+      os << "GESTURE_MULTI_TOUCH_DOWN";
+      break;
+    case GestureEventListener::GESTURE_PINCH:
+      os << "GESTURE_PINCH";
+      break;
+    case GestureEventListener::GESTURE_ONE_TOUCH_PINCH:
+      os << "GESTURE_ONE_TOUCH_PINCH";
+      break;
+  }
+
+  return os;
+}
+
 }  // namespace layers
 }  // namespace mozilla
diff --git a/gfx/layers/apz/src/GestureEventListener.h b/gfx/layers/apz/src/GestureEventListener.h
index aa51889fdd..bf50d4f40a 100644
--- a/gfx/layers/apz/src/GestureEventListener.h
+++ b/gfx/layers/apz/src/GestureEventListener.h
@@ -7,6 +7,7 @@
 #ifndef mozilla_layers_GestureEventListener_h
 #define mozilla_layers_GestureEventListener_h
 
+#include <iosfwd>
 #include "InputData.h"  // for MultiTouchInput, etc
 #include "Units.h"
 #include "mozilla/EventForwards.h"  // for nsEventStatus
@@ -135,6 +136,8 @@ class GestureEventListener final {
     GESTURE_ONE_TOUCH_PINCH
   };
 
+  friend std::ostream& operator<<(std::ostream& os, GestureState aState);
+
   /**
    * These HandleInput* functions comprise input alphabet of the GEL
    * finite-state machine triggering state transitions.
diff --git a/gfx/layers/apz/test/gtest/TestGestureDetector.cpp b/gfx/layers/apz/test/gtest/TestGestureDetector.cpp
index f244ca4dc7..8256667d6b 100644
--- a/gfx/layers/apz/test/gtest/TestGestureDetector.cpp
+++ b/gfx/layers/apz/test/gtest/TestGestureDetector.cpp
@@ -21,12 +21,12 @@ class APZCGestureDetectorTester : public APZCBasicTester {
       : APZCBasicTester(AsyncPanZoomController::USE_GESTURE_DETECTOR) {}
 
  protected:
-  FrameMetrics GetPinchableFrameMetrics() {
+  FrameMetrics GetPinchableFrameMetrics(float aZoom = 2.0f) {
     FrameMetrics fm;
     fm.SetCompositionBounds(ParentLayerRect(200, 200, 100, 200));
     fm.SetScrollableRect(CSSRect(0, 0, 980, 1000));
     fm.SetVisualScrollOffset(CSSPoint(300, 300));
-    fm.SetZoom(CSSToParentLayerScale(2.0));
+    fm.SetZoom(CSSToParentLayerScale(aZoom));
     // APZC only allows zooming on the root scrollable frame.
     fm.SetIsRootContent(true);
     // the visible area of the document in CSS pixels is x=300 y=300 w=50 h=100
@@ -843,3 +843,235 @@ TEST_F(APZCGestureDetectorTester, LongPressWithInputQueueDelay3) {
   mcc->AdvanceByMillis(1);
   check.Call("post long-tap dispatch");
 }
+
+TEST_F(APZCGestureDetectorTester, OneTouchPinchGestureShort) {
+  // Take less than StaticPrefs::apz_max_tap_time() until second touch down,
+  // hold second touch down for a very short time, then move
+  // and expect a successful one touch pinch gesture
+  SCOPED_GFX_PREF_BOOL("apz.one_touch_pinch.enabled", true);
+
+  MakeApzcZoomable();
+  apzc->SetFrameMetrics(GetPinchableFrameMetrics());
+  const auto oldZoom = apzc->GetFrameMetrics().GetZoom().scale;
+
+  const auto tapResult =
+      Tap(apzc, ScreenIntPoint(10, 10), TimeDuration::FromMilliseconds(10));
+  apzc->SetAllowedTouchBehavior(tapResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  mcc->AdvanceByMillis(10);
+  const auto touchResult = TouchDown(apzc, ScreenIntPoint(10, 10), mcc->Time());
+  apzc->SetAllowedTouchBehavior(touchResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  // We should be able to hold down the second touch as long as we like
+  // before beginning to move
+  mcc->AdvanceByMillis(10);
+  TouchMove(apzc, ScreenIntPoint(10, 50), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchMove(apzc, ScreenIntPoint(10, 150), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchUp(apzc, ScreenIntPoint(10, 150), mcc->Time());
+
+  const auto newZoom = apzc->GetFrameMetrics().GetZoom().scale;
+  EXPECT_NE(newZoom, oldZoom);
+}
+
+TEST_F(APZCGestureDetectorTester, OneTouchPinchGestureLong) {
+  // Take less than StaticPrefs::apz_max_tap_time() until second touch down,
+  // hold second touch down for a long time, then move
+  // and expect a successful one touch pinch gesture
+  SCOPED_GFX_PREF_BOOL("apz.one_touch_pinch.enabled", true);
+
+  MakeApzcZoomable();
+  apzc->SetFrameMetrics(GetPinchableFrameMetrics());
+  const auto oldZoom = apzc->GetFrameMetrics().GetZoom().scale;
+
+  const auto tapResult =
+      Tap(apzc, ScreenIntPoint(10, 10), TimeDuration::FromMilliseconds(10));
+  apzc->SetAllowedTouchBehavior(tapResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  mcc->AdvanceByMillis(StaticPrefs::apz_max_tap_time() - 20);
+  const auto touchResult = TouchDown(apzc, ScreenIntPoint(10, 10), mcc->Time());
+  apzc->SetAllowedTouchBehavior(touchResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  // We should be able to hold down the second touch as long as we like
+  // before beginning to move
+  mcc->AdvanceByMillis(StaticPrefs::apz_max_tap_time() + 100);
+  TouchMove(apzc, ScreenIntPoint(10, 50), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchMove(apzc, ScreenIntPoint(10, 150), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchUp(apzc, ScreenIntPoint(10, 150), mcc->Time());
+
+  const auto newZoom = apzc->GetFrameMetrics().GetZoom().scale;
+  EXPECT_NE(newZoom, oldZoom);
+}
+
+TEST_F(APZCGestureDetectorTester, OneTouchPinchGestureNoMoveTriggersDoubleTap) {
+  // Take less than StaticPrefs::apz_max_tap_time() until second touch down,
+  // then wait longer than StaticPrefs::apz_max_tap_time(), lift finger up
+  // and expect a successful double tap. No zooming should be performed
+  // by the one-touch pinch codepath.
+  SCOPED_GFX_PREF_BOOL("apz.one_touch_pinch.enabled", true);
+
+  apzc->SetFrameMetrics(GetPinchableFrameMetrics());
+  const auto oldZoom = apzc->GetFrameMetrics().GetZoom().scale;
+
+  MakeApzcZoomable();
+
+  EXPECT_CALL(*mcc, HandleTap(TapType::eSingleTap, _, 0, apzc->GetGuid(), _, _))
+      .Times(0);
+  EXPECT_CALL(*mcc,
+              HandleTap(TapType::eDoubleTap, _, 0, apzc->GetGuid(), _, _));
+
+  const auto tapResult =
+      Tap(apzc, ScreenIntPoint(10, 10), TimeDuration::FromMilliseconds(10));
+  apzc->SetAllowedTouchBehavior(tapResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  mcc->AdvanceByMillis(StaticPrefs::apz_max_tap_time() - 20);
+  const auto touchResult = TouchDown(apzc, ScreenIntPoint(10, 10), mcc->Time());
+  apzc->SetAllowedTouchBehavior(touchResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  // We should be able to hold down the second touch as long as we like
+  // before lifting the finger
+  mcc->AdvanceByMillis(StaticPrefs::apz_max_tap_time() + 100);
+  TouchUp(apzc, ScreenIntPoint(10, 10), mcc->Time());
+
+  const auto newZoom = apzc->GetFrameMetrics().GetZoom().scale;
+  EXPECT_EQ(newZoom, oldZoom);
+}
+
+TEST_F(APZCGestureDetectorTester, OneTouchPinchGestureNonZoomablePage) {
+  // Use a non-zoomable page. Perform a tap and a touch-drag
+  // which on a zoomable page trigger a one touch pinch gesture,
+  // and expect a single tap followed by a touch-scroll
+  SCOPED_GFX_PREF_BOOL("apz.one_touch_pinch.enabled", true);
+
+  apzc->SetFrameMetrics(GetPinchableFrameMetrics(1.0f));
+  const auto oldZoom = apzc->GetFrameMetrics().GetZoom().scale;
+  const auto oldScrollOffset = apzc->GetFrameMetrics().GetVisualScrollOffset();
+  MakeApzcUnzoomable();
+
+  EXPECT_CALL(*mcc, HandleTap(TapType::eSingleTap, _, 0, apzc->GetGuid(), _, _))
+      .Times(1);
+  EXPECT_CALL(*mcc, HandleTap(TapType::eDoubleTap, _, 0, apzc->GetGuid(), _, _))
+      .Times(0);
+
+  const auto tapResult =
+      Tap(apzc, ScreenIntPoint(10, 10), TimeDuration::FromMilliseconds(10));
+  apzc->SetAllowedTouchBehavior(tapResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  mcc->AdvanceByMillis(StaticPrefs::apz_max_tap_time() - 20);
+  const auto touchResult = TouchDown(apzc, ScreenIntPoint(10, 10), mcc->Time());
+  apzc->SetAllowedTouchBehavior(touchResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  // We should be able to hold down the second touch as long as we like
+  // before beginning to move
+  mcc->AdvanceByMillis(StaticPrefs::apz_max_tap_time() + 100);
+  TouchMove(apzc, ScreenIntPoint(10, 50), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchMove(apzc, ScreenIntPoint(10, 100), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchUp(apzc, ScreenIntPoint(10, 100), mcc->Time());
+
+  const auto newZoom = apzc->GetFrameMetrics().GetZoom().scale;
+  EXPECT_EQ(newZoom, oldZoom);
+
+  const auto newScrollOffset = apzc->GetFrameMetrics().GetVisualScrollOffset();
+  EXPECT_NE(newScrollOffset, oldScrollOffset);
+}
+
+TEST_F(APZCGestureDetectorTester, OneTouchPinchGestureTimeout) {
+  // Take longer than StaticPrefs::apz_max_tap_time() until second touch down
+  // and expect no one touch pinch gesture being performed
+  SCOPED_GFX_PREF_BOOL("apz.one_touch_pinch.enabled", true);
+
+  MakeApzcZoomable();
+  apzc->SetFrameMetrics(GetPinchableFrameMetrics());
+  const auto oldZoom = apzc->GetFrameMetrics().GetZoom().scale;
+
+  EXPECT_CALL(*mcc, HandleTap(TapType::eSingleTap, _, 0, apzc->GetGuid(), _, _))
+      .Times(1);
+
+  const auto tapResult =
+      Tap(apzc, ScreenIntPoint(10, 10), TimeDuration::FromMilliseconds(10));
+  apzc->SetAllowedTouchBehavior(tapResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  mcc->AdvanceByMillis(StaticPrefs::apz_max_tap_time());
+  const auto touchResult = TouchDown(apzc, ScreenIntPoint(10, 10), mcc->Time());
+  apzc->SetAllowedTouchBehavior(touchResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  mcc->AdvanceByMillis(10);
+  TouchMove(apzc, ScreenIntPoint(10, 50), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchMove(apzc, ScreenIntPoint(10, 150), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchUp(apzc, ScreenIntPoint(10, 150), mcc->Time());
+
+  const auto newZoom = apzc->GetFrameMetrics().GetZoom().scale;
+  EXPECT_EQ(newZoom, oldZoom);
+}
+
+TEST_F(APZCGestureDetectorTester, OneTouchPinchGestureDisabled) {
+  // With apz.one_touch_pinch disabled,
+  // perform one touch pinch gesture within the time threshold,
+  // and expect no zooming.
+  SCOPED_GFX_PREF_BOOL("apz.one_touch_pinch.enabled", false);
+
+  MakeApzcZoomable();
+  apzc->SetFrameMetrics(GetPinchableFrameMetrics());
+  const auto oldZoom = apzc->GetFrameMetrics().GetZoom().scale;
+  const auto oldScrollOffset = apzc->GetFrameMetrics().GetVisualScrollOffset();
+
+  // todo: enable following EXPECT_CALLs when fixing bug 1881794
+  // EXPECT_CALL(*mcc, HandleTap(TapType::eSingleTap, _, 0, apzc->GetGuid(), _,
+  // _))
+  //     .Times(1);
+  // EXPECT_CALL(*mcc, HandleTap(TapType::eDoubleTap, _, 0, apzc->GetGuid(), _,
+  // _))
+  //     .Times(0);
+
+  const auto tapResult =
+      Tap(apzc, ScreenIntPoint(10, 10), TimeDuration::FromMilliseconds(10));
+  apzc->SetAllowedTouchBehavior(tapResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  mcc->AdvanceByMillis(StaticPrefs::apz_max_tap_time() - 20);
+  const auto touchResult = TouchDown(apzc, ScreenIntPoint(10, 10), mcc->Time());
+  apzc->SetAllowedTouchBehavior(touchResult.mInputBlockId,
+                                {kDefaultTouchBehavior});
+
+  // We should be able to hold down the second touch as long as we like
+  // before beginning to move
+  mcc->AdvanceByMillis(StaticPrefs::apz_max_tap_time() + 100);
+  TouchMove(apzc, ScreenIntPoint(10, 50), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchMove(apzc, ScreenIntPoint(10, 150), mcc->Time());
+
+  mcc->AdvanceByMillis(10);
+  TouchUp(apzc, ScreenIntPoint(10, 150), mcc->Time());
+
+  const auto newZoom = apzc->GetFrameMetrics().GetZoom().scale;
+  EXPECT_EQ(newZoom, oldZoom);
+
+  const auto newScrollOffset = apzc->GetFrameMetrics().GetVisualScrollOffset();
+  EXPECT_NE(newScrollOffset, oldScrollOffset);
+}
diff --git a/gfx/layers/apz/test/mochitest/apz_test_native_event_utils.js b/gfx/layers/apz/test/mochitest/apz_test_native_event_utils.js
index c290965845..1642bc147a 100644
--- a/gfx/layers/apz/test/mochitest/apz_test_native_event_utils.js
+++ b/gfx/layers/apz/test/mochitest/apz_test_native_event_utils.js
@@ -498,7 +498,7 @@ async function promiseNativeTouchpadPanEventAndWaitForObserver(
 
   return new Promise(resolve => {
     var observer = {
-      observe(aSubject, aTopic, aData) {
+      observe(aSubject, aTopic) {
         if (aTopic == "touchpadpanevent") {
           resolve();
         }
@@ -557,7 +557,7 @@ function promiseNativePanGestureEventAndWaitForObserver(
 ) {
   return new Promise(resolve => {
     var observer = {
-      observe(aSubject, aTopic, aData) {
+      observe(aSubject, aTopic) {
         if (aTopic == "mousescrollevent") {
           resolve();
         }
@@ -588,7 +588,7 @@ function promiseNativeWheelAndWaitForObserver(
 ) {
   return new Promise(resolve => {
     var observer = {
-      observe(aSubject, aTopic, aData) {
+      observe(aSubject, aTopic) {
         if (aTopic == "mousescrollevent") {
           resolve();
         }
@@ -614,7 +614,7 @@ function promiseNativeWheelAndWaitForWheelEvent(
     var targetWindow = windowForTarget(aTarget);
     targetWindow.addEventListener(
       "wheel",
-      function (e) {
+      function () {
         setTimeout(resolve, 0);
       },
       { once: true }
@@ -1566,7 +1566,7 @@ function promiseScrollend(aTarget = window) {
 function promiseTouchEnd(element, count = 1) {
   return new Promise(resolve => {
     var eventCount = 0;
-    var counterFunction = function (e) {
+    var counterFunction = function () {
       eventCount++;
       if (eventCount == count) {
         element.removeEventListener("touchend", counterFunction, {
@@ -1816,7 +1816,7 @@ async function panRightToLeftUpdate(aElement, aX, aY, aMultiplier) {
   );
 }
 
-async function panRightToLeftEnd(aElement, aX, aY, aMultiplier) {
+async function panRightToLeftEnd(aElement, aX, aY) {
   await NativePanHandler.promiseNativePanEvent(
     aElement,
     aX,
@@ -1869,7 +1869,7 @@ async function panLeftToRightUpdate(aElement, aX, aY, aMultiplier) {
   );
 }
 
-async function panLeftToRightEnd(aElement, aX, aY, aMultiplier) {
+async function panLeftToRightEnd(aElement, aX, aY) {
   await NativePanHandler.promiseNativePanEvent(
     aElement,
     aX,
diff --git a/gfx/layers/apz/test/mochitest/apz_test_utils.js b/gfx/layers/apz/test/mochitest/apz_test_utils.js
index 821c66103d..cdae7824b2 100644
--- a/gfx/layers/apz/test/mochitest/apz_test_utils.js
+++ b/gfx/layers/apz/test/mochitest/apz_test_utils.js
@@ -309,7 +309,7 @@ function promiseAfterPaint() {
 // occurred by the the returned promise resolves. If you want to wait
 // for those repaints, consider using promiseApzFlushedRepaints instead.
 function promiseOnlyApzControllerFlushedWithoutSetTimeout(aWindow = window) {
-  return new Promise(function (resolve, reject) {
+  return new Promise(function (resolve) {
     var repaintDone = function () {
       dump("PromiseApzRepaintsFlushed: APZ flush done\n");
       SpecialPowers.Services.obs.removeObserver(
@@ -518,7 +518,7 @@ function runSubtestsSeriallyInFreshWindows(aSubtests) {
         if (test.onload) {
           w.addEventListener(
             "load",
-            function (e) {
+            function () {
               test.onload(w);
             },
             { once: true }
diff --git a/gfx/layers/apz/test/mochitest/browser.toml b/gfx/layers/apz/test/mochitest/browser.toml
index 5432aa0ae1..67428eee23 100644
--- a/gfx/layers/apz/test/mochitest/browser.toml
+++ b/gfx/layers/apz/test/mochitest/browser.toml
@@ -19,7 +19,7 @@ support-files = ["helper_test_autoscrolling_in_oop_frame.html"]
 support-files = ["helper_background_tab_load_scroll.html"]
 
 ["browser_test_background_tab_scroll.js"]
-skip-if = ["toolkit == 'android'"] # wheel events not supported on mobile
+skip-if = ["os == 'android'"] # wheel events not supported on mobile
 support-files = ["helper_background_tab_scroll.html"]
 
 ["browser_test_content_response_timeout.js"]
@@ -28,7 +28,7 @@ support-files = ["helper_content_response_timeout.html"]
 ["browser_test_group_fission.js"]
 skip-if = [
   "win11_2009 && bits == 32", # intermittent failures on on win11/32
-  "os == 'linux' && bits == 64", # Bug 1773830
+  "os == 'linux' && os_version == '18.04' && bits == 64", # Bug 1773830
 ]
 support-files = [
   "FissionTestHelperParent.sys.mjs",
@@ -49,7 +49,7 @@ support-files = ["helper_scroll_thumb_dragging.html"]
 ["browser_test_scrollbar_in_extension_popup_window.js"]
 skip-if = [
   "verify",
-  "os == 'linux'" # Bug 1713052
+  "os == 'linux' && os_version == '18.04'" # Bug 1713052
 ]
 
 ["browser_test_scrolling_in_extension_popup_window.js"]
@@ -70,7 +70,7 @@ skip-if = ["os == 'win'"] # bug 1495580
 support-files = ["helper_test_select_zoom.html"]
 
 ["browser_test_tab_drag_event_counts.js"]
-skip-if = ["os == 'linux'"] # No native key event support on Linux at this time (bug 1770143)
+skip-if = ["os == 'linux' && os_version == '18.04'"] # No native key event support on Linux at this time (bug 1770143)
 support-files = [
   "helper_test_tab_drag_event_counts.html"
 ]
diff --git a/gfx/layers/apz/test/mochitest/browser_test_autoscrolling_in_oop_frame.js b/gfx/layers/apz/test/mochitest/browser_test_autoscrolling_in_oop_frame.js
index 26d0ff6109..f7f83575f2 100644
--- a/gfx/layers/apz/test/mochitest/browser_test_autoscrolling_in_oop_frame.js
+++ b/gfx/layers/apz/test/mochitest/browser_test_autoscrolling_in_oop_frame.js
@@ -74,7 +74,7 @@ async function doTest() {
         return new Promise(resolve => {
           content.addEventListener(
             "scroll",
-            event => {
+            () => {
               dump("Got a scroll event in the iframe\n");
               resolve();
             },
diff --git a/gfx/layers/apz/test/mochitest/browser_test_content_response_timeout.js b/gfx/layers/apz/test/mochitest/browser_test_content_response_timeout.js
index a80fd77c17..98f6ea6c29 100644
--- a/gfx/layers/apz/test/mochitest/browser_test_content_response_timeout.js
+++ b/gfx/layers/apz/test/mochitest/browser_test_content_response_timeout.js
@@ -60,6 +60,7 @@ add_task(async () => {
   );
 
   await new Promise(resolve => {
+    // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
     setTimeout(resolve, 200);
   });
 
diff --git a/gfx/layers/apz/test/mochitest/browser_test_scrolling_in_extension_popup_window.js b/gfx/layers/apz/test/mochitest/browser_test_scrolling_in_extension_popup_window.js
index 6da3f3311b..9896e628e3 100644
--- a/gfx/layers/apz/test/mochitest/browser_test_scrolling_in_extension_popup_window.js
+++ b/gfx/layers/apz/test/mochitest/browser_test_scrolling_in_extension_popup_window.js
@@ -98,7 +98,7 @@ add_task(async () => {
       return new Promise(resolve => {
         content.window.addEventListener(
           "scroll",
-          event => {
+          () => {
             dump("Got a scroll event in the popup content document\n");
             resolve();
           },
diff --git a/gfx/layers/apz/test/mochitest/helper_basic_scrollend.html b/gfx/layers/apz/test/mochitest/helper_basic_scrollend.html
index 9d71fe6251..6c31859690 100644
--- a/gfx/layers/apz/test/mochitest/helper_basic_scrollend.html
+++ b/gfx/layers/apz/test/mochitest/helper_basic_scrollend.html
@@ -19,7 +19,7 @@ const searchParams = new URLSearchParams(location.search);
 async function test() {
   var scrollendCount = 0;
 
-  function onScrollend(e) {
+  function onScrollend() {
     scrollendCount += 1;
   }
 
diff --git a/gfx/layers/apz/test/mochitest/helper_browser_test_utils.js b/gfx/layers/apz/test/mochitest/helper_browser_test_utils.js
index ac68c9b1d4..22a072e48d 100644
--- a/gfx/layers/apz/test/mochitest/helper_browser_test_utils.js
+++ b/gfx/layers/apz/test/mochitest/helper_browser_test_utils.js
@@ -4,7 +4,7 @@ Services.scriptloader.loadSubScript(
   this
 );
 
-function openSelectPopup(selector = "select", win = window) {
+function openSelectPopup(selector, win = window) {
   let popupShownPromise = BrowserTestUtils.waitForSelectPopupShown(win);
   EventUtils.synthesizeKey("KEY_ArrowDown", { altKey: true }, win);
   return popupShownPromise;
diff --git a/gfx/layers/apz/test/mochitest/helper_bug1346632.html b/gfx/layers/apz/test/mochitest/helper_bug1346632.html
index f91f8159b5..c7f92c3810 100644
--- a/gfx/layers/apz/test/mochitest/helper_bug1346632.html
+++ b/gfx/layers/apz/test/mochitest/helper_bug1346632.html
@@ -28,7 +28,7 @@
 async function test() {
   var root = document.scrollingElement;
   var scrollPos = root.scrollTop;
-  var scrollPromise = new Promise((resolve, reject) => {
+  var scrollPromise = new Promise((resolve) => {
     document.addEventListener("scroll", () => {
       ok(root.scrollTop > scrollPos, "document scrolled after dragging scrollbar");
       resolve();
diff --git a/gfx/layers/apz/test/mochitest/helper_bug1414336.html b/gfx/layers/apz/test/mochitest/helper_bug1414336.html
index 636328b7e4..c0d35db401 100644
--- a/gfx/layers/apz/test/mochitest/helper_bug1414336.html
+++ b/gfx/layers/apz/test/mochitest/helper_bug1414336.html
@@ -62,14 +62,14 @@ waitUntilApzStable().then(async () => {
   let target0 = window.document.getElementById("target0");
   let target0_events = ["pointerdown", "pointermove"];
 
-  target0_events.forEach((elem, index, arr) => {
+  target0_events.forEach((elem) => {
     target0.addEventListener(elem, (event) => {
       is(event.type, target0_events[0], "receive " + event.type + " on target0");
       target0_events.shift();
     }, { once: true });
   });
 
-  target0.addEventListener("pointercancel", (event) => {
+  target0.addEventListener("pointercancel", () => {
     ok(false, "Shouldn't receive pointercancel when content prevents default on touchstart");
     // Wait until the event is done processing before we end the subtest,
     // otherwise on Android the pointer events pref is flipped back to false
@@ -81,7 +81,7 @@ waitUntilApzStable().then(async () => {
     event.preventDefault();
   }, { once: true });
 
-  target0.addEventListener("pointerup", (event) => {
+  target0.addEventListener("pointerup", () => {
     ok(!target0_events.length, " should receive " + target0_events + " on target0");
     // Wait until the event is done processing before we end the subtest,
     // otherwise on Android the pointer events pref is flipped back to false
diff --git a/gfx/layers/apz/test/mochitest/helper_bug1502010_unconsumed_pan.html b/gfx/layers/apz/test/mochitest/helper_bug1502010_unconsumed_pan.html
index 73badf4bc7..8534e8886b 100644
--- a/gfx/layers/apz/test/mochitest/helper_bug1502010_unconsumed_pan.html
+++ b/gfx/layers/apz/test/mochitest/helper_bug1502010_unconsumed_pan.html
@@ -38,7 +38,7 @@
 
     async function test() {
         var target = document.getElementById("carousel");
-        target.addEventListener("pointercancel", (event) => {
+        target.addEventListener("pointercancel", () => {
             ok(false, "Received pointercancel, uh-oh!");
             endEventReceived = true;
             setTimeout(checkForTestEnd, 0);
diff --git a/gfx/layers/apz/test/mochitest/helper_bug1506497_touch_action_fixed_on_fixed.html b/gfx/layers/apz/test/mochitest/helper_bug1506497_touch_action_fixed_on_fixed.html
index cc73fe99ea..b853bde04d 100644
--- a/gfx/layers/apz/test/mochitest/helper_bug1506497_touch_action_fixed_on_fixed.html
+++ b/gfx/layers/apz/test/mochitest/helper_bug1506497_touch_action_fixed_on_fixed.html
@@ -11,7 +11,7 @@
   <script type="application/javascript">
 
 async function test() {
-  document.getElementById("overlay").addEventListener("touchstart", function(e) {
+  document.getElementById("overlay").addEventListener("touchstart", function() {
     // no need to do anything here. Just having a non-passive touchstart
     // listener will force APZ to wait for the main thread to handle the
     // touch event. The bug is that the touch-action:none property on the
@@ -34,7 +34,7 @@ async function test() {
   // This promise will resolve after the main thread has processed
   // all the synthesized touch events.
   let promiseTouchEnd = new Promise(resolve => {
-    var waitForTouchEnd = function(e) {
+    var waitForTouchEnd = function() {
       dump("touchend listener hit\n");
       resolve();
     };
diff --git a/gfx/layers/apz/test/mochitest/helper_bug1695598.html b/gfx/layers/apz/test/mochitest/helper_bug1695598.html
index fb6102e33d..7961d7ced4 100644
--- a/gfx/layers/apz/test/mochitest/helper_bug1695598.html
+++ b/gfx/layers/apz/test/mochitest/helper_bug1695598.html
@@ -19,7 +19,7 @@
     let utils = SpecialPowers.getDOMWindowUtils(window);
 
     let timeStamp = document.timeline.currentTime;
-    async function sendScrollEvent(aRafTimestamp) {
+    async function sendScrollEvent() {
       if (i < scrollEvents) {
         if (timeStamp == document.timeline.currentTime) {
           // If we are in a rAF callback at the same time stamp we've already
diff --git a/gfx/layers/apz/test/mochitest/helper_content_response_timeout.html b/gfx/layers/apz/test/mochitest/helper_content_response_timeout.html
index 41a0319699..c0481d01a4 100644
--- a/gfx/layers/apz/test/mochitest/helper_content_response_timeout.html
+++ b/gfx/layers/apz/test/mochitest/helper_content_response_timeout.html
@@ -11,7 +11,7 @@ div { height: 1000vh; }
 </style>
 <div id='target'></div>
 <script>
-window.addEventListener('wheel', (e) => {
+window.addEventListener('wheel', () => {
  const timeAtStart = window.performance.now();
  while (window.performance.now() - timeAtStart < 200) {
   // Make a 200ms busy state.
diff --git a/gfx/layers/apz/test/mochitest/helper_displayport_expiry.html b/gfx/layers/apz/test/mochitest/helper_displayport_expiry.html
index 023786a270..b463e4f39c 100644
--- a/gfx/layers/apz/test/mochitest/helper_displayport_expiry.html
+++ b/gfx/layers/apz/test/mochitest/helper_displayport_expiry.html
@@ -53,7 +53,7 @@ async function test() {
   await promiseFrame();
 
   let paintCount = 0;
-  function countPaints(e) {
+  function countPaints() {
     paintCount += 1;
   }
 
diff --git a/gfx/layers/apz/test/mochitest/helper_fission_event_region_override.html b/gfx/layers/apz/test/mochitest/helper_fission_event_region_override.html
index 82f529bebd..8ebfc492f2 100644
--- a/gfx/layers/apz/test/mochitest/helper_fission_event_region_override.html
+++ b/gfx/layers/apz/test/mochitest/helper_fission_event_region_override.html
@@ -29,7 +29,7 @@ let code_for_oopif_to_run = function() {
     let result = { x: e.clientX, y: e.clientY };
     FissionTestHelper.fireEventInEmbedder("OOPIF:WheelData", result);
   }, { passive: true });
-  document.addEventListener("scroll", function(e) {
+  document.addEventListener("scroll", function() {
     dump(`OOPIF got scroll to ${window.scrollX},${window.scrollY}\n`);
     let result = { x: window.scrollX, y: window.scrollY };
     FissionTestHelper.fireEventInEmbedder("OOPIF:Scrolled", result);
diff --git a/gfx/layers/apz/test/mochitest/helper_fission_scroll_oopif.html b/gfx/layers/apz/test/mochitest/helper_fission_scroll_oopif.html
index 2911b1eaf0..5a192c9f9e 100644
--- a/gfx/layers/apz/test/mochitest/helper_fission_scroll_oopif.html
+++ b/gfx/layers/apz/test/mochitest/helper_fission_scroll_oopif.html
@@ -66,7 +66,7 @@ let make_oopif_scrollable = function() {
     FissionTestHelper.fireEventInEmbedder("OOPIF:Scrollable", result);
   });
   // Also register a scroll listener for when it actually gets scrolled.
-  window.addEventListener("scroll", function(e) {
+  window.addEventListener("scroll", function() {
     dump(`OOPIF got scroll event, now at ${window.scrollY}\n`);
     let result = { y: window.scrollY };
     FissionTestHelper.fireEventInEmbedder("OOPIF:Scrolled", result);
diff --git a/gfx/layers/apz/test/mochitest/helper_fullscreen.html b/gfx/layers/apz/test/mochitest/helper_fullscreen.html
index 32de4979f2..7ac443a1cc 100644
--- a/gfx/layers/apz/test/mochitest/helper_fullscreen.html
+++ b/gfx/layers/apz/test/mochitest/helper_fullscreen.html
@@ -27,7 +27,7 @@
       });
     }
 
-    async function test(testDriver) {
+    async function test() {
       target.requestFullscreen();
 
       await waitForFullscreenChange();
diff --git a/gfx/layers/apz/test/mochitest/helper_hittest_deep_scene_stack.html b/gfx/layers/apz/test/mochitest/helper_hittest_deep_scene_stack.html
index a04b1d3e83..30a9740d24 100644
--- a/gfx/layers/apz/test/mochitest/helper_hittest_deep_scene_stack.html
+++ b/gfx/layers/apz/test/mochitest/helper_hittest_deep_scene_stack.html
@@ -38,7 +38,7 @@ for (var i = 3; i < 1000; i++) {
 }
 document.body.appendChild(div);
 
-async function test(testDriver) {
+async function test() {
   var config = getHitTestConfig();
   var utils = config.utils;
 
diff --git a/gfx/layers/apz/test/mochitest/helper_hittest_fixed-2.html b/gfx/layers/apz/test/mochitest/helper_hittest_fixed-2.html
index 0f20719d46..b83b864aa2 100644
--- a/gfx/layers/apz/test/mochitest/helper_hittest_fixed-2.html
+++ b/gfx/layers/apz/test/mochitest/helper_hittest_fixed-2.html
@@ -45,7 +45,7 @@ async function test() {
       e.stopPropagation();  // do not propagate event to |fixed| ancestor
       resolve();
     });
-    fixed.addEventListener("click", e => {
+    fixed.addEventListener("click", () => {
       // Since target's listener calls stopPropagation(), if we get here
       // then the coordinates of the click event did not correspond to
       // |target|, but somewhere else on |fixed|.
diff --git a/gfx/layers/apz/test/mochitest/helper_hittest_fixed-3.html b/gfx/layers/apz/test/mochitest/helper_hittest_fixed-3.html
index 2004ea9ae4..092c5b0dfa 100644
--- a/gfx/layers/apz/test/mochitest/helper_hittest_fixed-3.html
+++ b/gfx/layers/apz/test/mochitest/helper_hittest_fixed-3.html
@@ -72,7 +72,7 @@ async function test() {
       e.stopPropagation();  // do not propagate event to ancestors
       resolve();
     });
-    fixed.addEventListener("click", e => {
+    fixed.addEventListener("click", () => {
       // Since target's listener calls stopPropagation(), if we get here
       // then the coordinates of the click event did not correspond to
       // |target|, but somewhere else on |fixed|.
@@ -82,7 +82,7 @@ async function test() {
       todo(false, "Fixed ancestor should not be hit");
       resolve();
     });
-    window.addEventListener("click", e => {
+    window.addEventListener("click", () => {
       // Similarly, the root content document's window should not be hit.
       ok(false, "Root document should not be hit");
       resolve();
diff --git a/gfx/layers/apz/test/mochitest/helper_hittest_fixed.html b/gfx/layers/apz/test/mochitest/helper_hittest_fixed.html
index 530c53fd7a..3185d83bf5 100644
--- a/gfx/layers/apz/test/mochitest/helper_hittest_fixed.html
+++ b/gfx/layers/apz/test/mochitest/helper_hittest_fixed.html
@@ -53,7 +53,7 @@ async function test() {
       e.stopPropagation();  // do not propagate event to |fixed| ancestor
       resolve();
     });
-    fixed.addEventListener("click", e => {
+    fixed.addEventListener("click", () => {
       // Since target's listener calls stopPropagation(), if we get here
       // then the coordinates of the click event did not correspond to
       // |target|, but somewhere else on |fixed|.
diff --git a/gfx/layers/apz/test/mochitest/helper_hittest_hidden_inactive_scrollframe.html b/gfx/layers/apz/test/mochitest/helper_hittest_hidden_inactive_scrollframe.html
index 0abed82156..6d9ea7bc53 100644
--- a/gfx/layers/apz/test/mochitest/helper_hittest_hidden_inactive_scrollframe.html
+++ b/gfx/layers/apz/test/mochitest/helper_hittest_hidden_inactive_scrollframe.html
@@ -26,7 +26,7 @@
 </body>
 <script type="application/javascript">
 
-function test(testDriver) {
+function test() {
   var config = getHitTestConfig();
   var utils = config.utils;
 
diff --git a/gfx/layers/apz/test/mochitest/helper_hittest_iframe_perspective-2.html b/gfx/layers/apz/test/mochitest/helper_hittest_iframe_perspective-2.html
index 9838a02aa9..b6128aaa87 100644
--- a/gfx/layers/apz/test/mochitest/helper_hittest_iframe_perspective-2.html
+++ b/gfx/layers/apz/test/mochitest/helper_hittest_iframe_perspective-2.html
@@ -44,7 +44,7 @@ async function test() {
       }
     });
 
-    window.addEventListener("mousedown", event => {
+    window.addEventListener("mousedown", () => {
       ok(true, "Parent document should have received mouse-down");
       resolve();
     });
diff --git a/gfx/layers/apz/test/mochitest/helper_hittest_overscroll.html b/gfx/layers/apz/test/mochitest/helper_hittest_overscroll.html
index c245258b68..c33dff3f28 100644
--- a/gfx/layers/apz/test/mochitest/helper_hittest_overscroll.html
+++ b/gfx/layers/apz/test/mochitest/helper_hittest_overscroll.html
@@ -63,7 +63,7 @@ function startListeningForClickEventsInChrome() {
       topWin = Services.wm.getMostRecentWindow("navigator:geckoview");
     }
     let chromeReceivedClick = false;
-    function chromeListener(e) {
+    function chromeListener() {
       chromeReceivedClick = true;
     }
     topWin.addEventListener("click", chromeListener);
diff --git a/gfx/layers/apz/test/mochitest/helper_hittest_overscroll_contextmenu.html b/gfx/layers/apz/test/mochitest/helper_hittest_overscroll_contextmenu.html
index 8aff3103dd..0bb3972c8a 100644
--- a/gfx/layers/apz/test/mochitest/helper_hittest_overscroll_contextmenu.html
+++ b/gfx/layers/apz/test/mochitest/helper_hittest_overscroll_contextmenu.html
@@ -43,7 +43,7 @@ function startListeningForContextmenuEventsInChrome() {
       topWin = Services.wm.getMostRecentWindow("navigator:geckoview");
     }
     let chromeReceivedContextmenu = false;
-    function chromeListener(e) {
+    function chromeListener() {
       chromeReceivedContextmenu = true;
     }
     topWin.addEventListener("contextmenu", chromeListener);
@@ -95,7 +95,7 @@ async function test() {
   let midGutter = 4 / deviceScale;  // gutter is 8 *screen* pixels
   startListeningForContextmenuEventsInChrome();
   let contentReceivedContextmenu = false;
-  let contentListener = function(e) {
+  let contentListener = function() {
     contentReceivedContextmenu = true;
   };
   document.addEventListener("contextmenu", contentListener);
diff --git a/gfx/layers/apz/test/mochitest/helper_hittest_overscroll_subframe.html b/gfx/layers/apz/test/mochitest/helper_hittest_overscroll_subframe.html
index 36918b3682..ff97c34bd5 100644
--- a/gfx/layers/apz/test/mochitest/helper_hittest_overscroll_subframe.html
+++ b/gfx/layers/apz/test/mochitest/helper_hittest_overscroll_subframe.html
@@ -84,7 +84,7 @@ async function test() {
   // This makes sure we catch the case where the overscroll transform causes
   // the event to incorrectly target the document.
   let receivedClick = false;
-  let listener = function(e) {
+  let listener = function() {
     receivedClick = true;
   };
   document.addEventListener("click", listener);
diff --git a/gfx/layers/apz/test/mochitest/helper_key_scroll.html b/gfx/layers/apz/test/mochitest/helper_key_scroll.html
index 021e2803b7..4f574abd10 100644
--- a/gfx/layers/apz/test/mochitest/helper_key_scroll.html
+++ b/gfx/layers/apz/test/mochitest/helper_key_scroll.html
@@ -32,7 +32,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1383365
       // page. This scroll is done synchronously because APZ doesn't have
       // current focus state at page load.
       let scrollBottomPromise = new Promise(resolve => {
-        let checkBottom = function(e) {
+        let checkBottom = function() {
           if (window.scrollY < window.scrollMaxY) {
             return;
           }
@@ -63,7 +63,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1383365
 
       // This scroll should be asynchronous now that the focus state is up to date.
       let scrollTopPromise = new Promise(resolve => {
-        let checkTop = function(e) {
+        let checkTop = function() {
           if (window.scrollY > 0) {
             return;
           }
diff --git a/gfx/layers/apz/test/mochitest/helper_main_thread_smooth_scroll_scrollend.html b/gfx/layers/apz/test/mochitest/helper_main_thread_smooth_scroll_scrollend.html
index 4f07db516e..c4a98ec7fa 100644
--- a/gfx/layers/apz/test/mochitest/helper_main_thread_smooth_scroll_scrollend.html
+++ b/gfx/layers/apz/test/mochitest/helper_main_thread_smooth_scroll_scrollend.html
@@ -25,7 +25,7 @@
 async function test() {
   let scrollendCount = 0;
 
-  window.addEventListener("scrollend", e => {
+  window.addEventListener("scrollend", () => {
     scrollendCount += 1;
   });
 
diff --git a/gfx/layers/apz/test/mochitest/helper_minimum_scale_1_0.html b/gfx/layers/apz/test/mochitest/helper_minimum_scale_1_0.html
index 17ccb3a54d..9c98ecf727 100644
--- a/gfx/layers/apz/test/mochitest/helper_minimum_scale_1_0.html
+++ b/gfx/layers/apz/test/mochitest/helper_minimum_scale_1_0.html
@@ -22,7 +22,7 @@
   <script type="application/javascript">
     const utils = SpecialPowers.getDOMWindowUtils(window);
 
-    async function test(testDriver) {
+    async function test() {
       utils.scrollToVisual(100, 0, utils.UPDATE_TYPE_MAIN_THREAD,
                            utils.SCROLL_MODE_INSTANT);
 
diff --git a/gfx/layers/apz/test/mochitest/helper_no_scalable_with_initial_scale.html b/gfx/layers/apz/test/mochitest/helper_no_scalable_with_initial_scale.html
index 7280a26006..1c26fafdb7 100644
--- a/gfx/layers/apz/test/mochitest/helper_no_scalable_with_initial_scale.html
+++ b/gfx/layers/apz/test/mochitest/helper_no_scalable_with_initial_scale.html
@@ -22,7 +22,7 @@
   <script type="application/javascript">
     const utils = SpecialPowers.getDOMWindowUtils(window);
 
-    async function test(testDriver) {
+    async function test() {
       utils.scrollToVisual(100, 0, utils.UPDATE_TYPE_MAIN_THREAD,
                            utils.SCROLL_MODE_INSTANT);
 
diff --git a/gfx/layers/apz/test/mochitest/helper_programmatic_scroll_behavior.html b/gfx/layers/apz/test/mochitest/helper_programmatic_scroll_behavior.html
index 721ce7e538..755c4115e2 100644
--- a/gfx/layers/apz/test/mochitest/helper_programmatic_scroll_behavior.html
+++ b/gfx/layers/apz/test/mochitest/helper_programmatic_scroll_behavior.html
@@ -35,7 +35,7 @@ async function test() {
   // trigger one scroll event, so a scroll event count of 1 indicates that a
   // instant scroll was conducted.
   let scrollCount = 0;
-  window.addEventListener("scroll", (e) => {
+  window.addEventListener("scroll", () => {
     scrollCount += 1;
   });
 
diff --git a/gfx/layers/apz/test/mochitest/helper_touch_action_regions.html b/gfx/layers/apz/test/mochitest/helper_touch_action_regions.html
index 6a8a09e55a..14e800a561 100644
--- a/gfx/layers/apz/test/mochitest/helper_touch_action_regions.html
+++ b/gfx/layers/apz/test/mochitest/helper_touch_action_regions.html
@@ -293,7 +293,7 @@ function* test(testDriver) {
 //   waitUntilApzStable().then(runContinuation(myTest));
 function runContinuation(testFunction) {
   return function() {
-    return new Promise(function(resolve, reject) {
+    return new Promise(function(resolve) {
       var testContinuation = null;
 
       function driveTest() {
diff --git a/gfx/layers/apz/test/mochitest/helper_zoomed_pan.html b/gfx/layers/apz/test/mochitest/helper_zoomed_pan.html
index 98547fb73f..0692c2f588 100644
--- a/gfx/layers/apz/test/mochitest/helper_zoomed_pan.html
+++ b/gfx/layers/apz/test/mochitest/helper_zoomed_pan.html
@@ -42,7 +42,7 @@
           x: 0,
           y: 0,
           dx: (width) => -computeDelta(width),
-          dy: (height) => 0,
+          dy: () => 0,
           expected: {
             x: [OFFSET_CSS_PX, "x-offset was adjusted"],
             y: [0, "y-offset was not affected"],
@@ -51,7 +51,7 @@
         {
           x: OFFSET_CSS_PX,
           y: 0,
-          dx: (width) => 0,
+          dx: () => 0,
           dy: (height) => -computeDelta(height),
           expected: {
             x: [OFFSET_CSS_PX, "x-offset was not affected"],
diff --git a/gfx/layers/apz/test/mochitest/test_smoothness.html b/gfx/layers/apz/test/mochitest/test_smoothness.html
index 64cb8bcefa..0f2ca3219e 100644
--- a/gfx/layers/apz/test/mochitest/test_smoothness.html
+++ b/gfx/layers/apz/test/mochitest/test_smoothness.html
@@ -23,7 +23,7 @@
     SimpleTest.waitForExplicitFinish();
     var utils = SpecialPowers.getDOMWindowUtils(window);
 
-    async function sendScrollEvent(aRafTimestamp) {
+    async function sendScrollEvent() {
       var scrollDiv = document.getElementById("content");
 
       if (i < scrollEvents) {
diff --git a/gfx/layers/apz/test/mochitest/test_touch_listeners_impacting_wheel.html b/gfx/layers/apz/test/mochitest/test_touch_listeners_impacting_wheel.html
index 71147d5238..0598f1a201 100644
--- a/gfx/layers/apz/test/mochitest/test_touch_listeners_impacting_wheel.html
+++ b/gfx/layers/apz/test/mochitest/test_touch_listeners_impacting_wheel.html
@@ -27,7 +27,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1203140
 
 const kResponseTimeoutMs = 2 * 60 * 1000; // 2 minutes
 
-function takeSnapshots(e) {
+function takeSnapshots() {
   // Grab some snapshots, and make sure some of them are different (i.e. check
   // the page is scrolling in the compositor, concurrently with this wheel
   // listener running).
@@ -69,7 +69,7 @@ async function test() {
   // Ensure the div is layerized by scrolling it
   await promiseMoveMouseAndScrollWheelOver(box, 10, 10);
 
-  box.addEventListener("touchstart", function(e) {
+  box.addEventListener("touchstart", function() {
     ok(false, "This should never be run");
   });
   box.addEventListener("wheel", takeSnapshots, { capture: false, passive: true });
diff --git a/gfx/layers/apz/test/reftest/reftest.list b/gfx/layers/apz/test/reftest/reftest.list
index 77bfff3e6e..9af67384a8 100644
--- a/gfx/layers/apz/test/reftest/reftest.list
+++ b/gfx/layers/apz/test/reftest/reftest.list
@@ -1,14 +1,14 @@
 # The following tests test the async positioning of the scrollbars.
 # Basic root-frame scrollbar with async scrolling
 # First make sure that we are actually drawing scrollbars
-skip-if(!asyncPan) pref(apz.allow_zooming,true) != async-scrollbar-1-v.html about:blank
-skip-if(!asyncPan) pref(apz.allow_zooming,true) != async-scrollbar-1-v-ref.html about:blank
-fuzzy-if(Android,0-5,0-6) fuzzy-if(gtkWidget,1-8,8-32) fuzzy-if(cocoaWidget,16-22,20-44) skip-if(!asyncPan) pref(apz.allow_zooming,true) == async-scrollbar-1-v.html async-scrollbar-1-v-ref.html
-fuzzy-if(Android,0-13,0-10) fuzzy-if(gtkWidget,1-30,4-32) fuzzy-if(cocoaWidget,14-22,20-44) skip-if(!asyncPan) pref(apz.allow_zooming,true) == async-scrollbar-1-h.html async-scrollbar-1-h-ref.html
-fuzzy-if(Android,0-13,0-21) fuzzy-if(gtkWidget,1-4,4-24) fuzzy-if(cocoaWidget,11-18,44-88) skip-if(!asyncPan) pref(apz.allow_zooming,true) == async-scrollbar-1-vh.html async-scrollbar-1-vh-ref.html
-fuzzy-if(Android,0-5,0-6) fuzzy-if(gtkWidget,1-8,8-32) fuzzy-if(cocoaWidget,16-22,20-44) skip-if(!asyncPan) pref(apz.allow_zooming,true) == async-scrollbar-1-v-rtl.html async-scrollbar-1-v-rtl-ref.html
-fuzzy-if(Android,0-14,0-10) fuzzy-if(gtkWidget,1-30,12-32) fuzzy-if(cocoaWidget,14-22,20-44) skip-if(!asyncPan) pref(apz.allow_zooming,true) == async-scrollbar-1-h-rtl.html async-scrollbar-1-h-rtl-ref.html
-fuzzy-if(Android,0-43,0-26) fuzzy-if(gtkWidget,0-14,12-32) fuzzy-if(cocoaWidget,11-18,26-76) skip-if(!asyncPan) pref(apz.allow_zooming,true) == async-scrollbar-1-vh-rtl.html async-scrollbar-1-vh-rtl-ref.html
+skip-if(useDrawSnapshot) pref(apz.allow_zooming,true) != async-scrollbar-1-v.html about:blank
+skip-if(useDrawSnapshot) pref(apz.allow_zooming,true) != async-scrollbar-1-v-ref.html about:blank
+fuzzy-if(Android,0-5,0-6) fuzzy-if(gtkWidget,1-8,8-32) fuzzy-if(cocoaWidget,16-22,20-44) skip-if(useDrawSnapshot) pref(apz.allow_zooming,true) == async-scrollbar-1-v.html async-scrollbar-1-v-ref.html
+fuzzy-if(Android,0-13,0-10) fuzzy-if(gtkWidget,1-30,4-32) fuzzy-if(cocoaWidget,14-22,20-44) skip-if(useDrawSnapshot) pref(apz.allow_zooming,true) == async-scrollbar-1-h.html async-scrollbar-1-h-ref.html
+fuzzy-if(Android,0-13,0-21) fuzzy-if(gtkWidget,1-4,4-24) fuzzy-if(cocoaWidget,11-18,44-88) skip-if(useDrawSnapshot) pref(apz.allow_zooming,true) == async-scrollbar-1-vh.html async-scrollbar-1-vh-ref.html
+fuzzy-if(Android,0-5,0-6) fuzzy-if(gtkWidget,1-8,8-32) fuzzy-if(cocoaWidget,16-22,20-44) skip-if(useDrawSnapshot) pref(apz.allow_zooming,true) == async-scrollbar-1-v-rtl.html async-scrollbar-1-v-rtl-ref.html
+fuzzy-if(Android,0-14,0-10) fuzzy-if(gtkWidget,1-30,12-32) fuzzy-if(cocoaWidget,14-22,20-44) skip-if(useDrawSnapshot) pref(apz.allow_zooming,true) == async-scrollbar-1-h-rtl.html async-scrollbar-1-h-rtl-ref.html
+fuzzy-if(Android,0-43,0-26) fuzzy-if(gtkWidget,0-14,12-32) fuzzy-if(cocoaWidget,11-18,26-76) skip-if(useDrawSnapshot) pref(apz.allow_zooming,true) == async-scrollbar-1-vh-rtl.html async-scrollbar-1-vh-rtl-ref.html
 
 # Different async zoom levels. Since the scrollthumb gets async-scaled in the
 # compositor, the border-radius ends of the scrollthumb are going to be a little
@@ -37,7 +37,7 @@ fuzzy-if(Android,0-28,0-23) fuzzy-if(!Android,0-107,0-34) pref(apz.allow_zooming
 # Meta-viewport tag support
 skip-if(!Android) pref(apz.allow_zooming,true) == initial-scale-1.html initial-scale-1-ref.html
 
-skip-if(!asyncPan) == frame-reconstruction-scroll-clamping.html frame-reconstruction-scroll-clamping-ref.html
+skip-if(useDrawSnapshot) == frame-reconstruction-scroll-clamping.html frame-reconstruction-scroll-clamping-ref.html
 
 # Test that position:fixed and position:sticky elements are attached to the
 # layout viewport.
diff --git a/gfx/layers/apz/testutil/APZTestData.h b/gfx/layers/apz/testutil/APZTestData.h
index e4a73c80cc..d180bbcf1d 100644
--- a/gfx/layers/apz/testutil/APZTestData.h
+++ b/gfx/layers/apz/testutil/APZTestData.h
@@ -144,10 +144,10 @@ class APZTestData {
 // A helper class for logging data for a paint.
 class APZPaintLogHelper {
  public:
-  APZPaintLogHelper(APZTestData* aTestData, SequenceNumber aPaintSequenceNumber)
+  APZPaintLogHelper(APZTestData* aTestData, SequenceNumber aPaintSequenceNumber,
+                    bool aIsTestLoggingEnabled)
       : mTestData(aTestData), mPaintSequenceNumber(aPaintSequenceNumber) {
-    MOZ_ASSERT(!aTestData || StaticPrefs::apz_test_logging_enabled(),
-               "don't call me");
+    MOZ_ASSERT(!aTestData || aIsTestLoggingEnabled, "don't call me");
   }
 
   template <typename Value>
diff --git a/gfx/layers/apz/util/APZCCallbackHelper.cpp b/gfx/layers/apz/util/APZCCallbackHelper.cpp
index 9ad65ce981..508cd8e67f 100644
--- a/gfx/layers/apz/util/APZCCallbackHelper.cpp
+++ b/gfx/layers/apz/util/APZCCallbackHelper.cpp
@@ -518,7 +518,8 @@ nsEventStatus APZCCallbackHelper::DispatchSynthesizedMouseEvent(
                          WidgetMouseEvent::eNormal);
   event.mRefPoint = LayoutDeviceIntPoint::Truncate(aRefPoint.x, aRefPoint.y);
   event.mButton = MouseButton::ePrimary;
-  event.mButtons |= MouseButtonsFlag::ePrimaryFlag;
+  event.mButtons = aMsg == eMouseDown ? MouseButtonsFlag::ePrimaryFlag
+                                      : MouseButtonsFlag::eNoButtons;
   event.mInputSource = dom::MouseEvent_Binding::MOZ_SOURCE_TOUCH;
   if (aMsg == eMouseLongTap) {
     event.mFlags.mOnlyChromeDispatch = true;
diff --git a/gfx/layers/apz/util/APZEventState.cpp b/gfx/layers/apz/util/APZEventState.cpp
index 7384296f45..5db6a08429 100644
--- a/gfx/layers/apz/util/APZEventState.cpp
+++ b/gfx/layers/apz/util/APZEventState.cpp
@@ -240,7 +240,7 @@ void APZEventState::ProcessLongTap(PresShell* aPresShell,
       false;
 #elif defined(MOZ_WIDGET_ANDROID)
       // On Android, GeckoView calls preventDefault() in a JSActor
-      // (ContentDelegateChild.jsm) when opening context menu so that we can
+      // (ContentDelegateChild.sys.mjs) when opening context menu so that we can
       // tell whether contextmenu opens in response to the contextmenu event by
       // checking where preventDefault() got called.
       preventDefaultResult == PreventDefaultResult::ByChrome;
diff --git a/gfx/layers/client/TextureClient.cpp b/gfx/layers/client/TextureClient.cpp
index bfc20b9b08..4187e48955 100644
--- a/gfx/layers/client/TextureClient.cpp
+++ b/gfx/layers/client/TextureClient.cpp
@@ -27,6 +27,7 @@
 #include "mozilla/gfx/gfxVars.h"
 #include "mozilla/ipc/CrossProcessSemaphore.h"
 #include "mozilla/ipc/SharedMemory.h"  // for SharedMemory, etc
+#include "mozilla/layers/CanvasRenderer.h"
 #include "mozilla/layers/CompositableForwarder.h"
 #include "mozilla/layers/ISurfaceAllocator.h"
 #include "mozilla/layers/ImageBridgeChild.h"
@@ -375,7 +376,8 @@ TextureData* TextureData::Create(TextureForwarder* aAllocator,
     RefPtr<CanvasChild> canvasChild = aAllocator->GetCanvasChild();
     if (canvasChild) {
       return new RecordedTextureData(canvasChild.forget(), aSize, aFormat,
-                                     textureType);
+                                     textureType,
+                                     layers::TexTypeForWebgl(aKnowsCompositor));
     }
     // If we must be remote, but there is no canvas child, then falling back
     // is not possible.
@@ -746,12 +748,10 @@ void TextureClient::ReadUnlock() {
 }
 
 bool TextureClient::Lock(OpenMode aMode) {
-  MOZ_ASSERT(IsValid());
-  MOZ_ASSERT(!mIsLocked);
-  if (!IsValid()) {
+  if (NS_WARN_IF(!IsValid())) {
     return false;
   }
-  if (mIsLocked) {
+  if (NS_WARN_IF(mIsLocked)) {
     return mOpenMode == aMode;
   }
 
diff --git a/gfx/layers/client/TextureRecorded.cpp b/gfx/layers/client/TextureRecorded.cpp
index 7e7ee2da99..da4ca4f8f3 100644
--- a/gfx/layers/client/TextureRecorded.cpp
+++ b/gfx/layers/client/TextureRecorded.cpp
@@ -23,9 +23,10 @@ static int64_t sNextRecordedTextureId = 0;
 
 RecordedTextureData::RecordedTextureData(
     already_AddRefed<CanvasChild> aCanvasChild, gfx::IntSize aSize,
-    gfx::SurfaceFormat aFormat, TextureType aTextureType)
+    gfx::SurfaceFormat aFormat, TextureType aTextureType,
+    TextureType aWebglTextureType)
     : mCanvasChild(aCanvasChild), mSize(aSize), mFormat(aFormat) {
-  mCanvasChild->EnsureRecorder(aSize, aFormat, aTextureType);
+  mCanvasChild->EnsureRecorder(aSize, aFormat, aTextureType, aWebglTextureType);
 }
 
 RecordedTextureData::~RecordedTextureData() {
diff --git a/gfx/layers/client/TextureRecorded.h b/gfx/layers/client/TextureRecorded.h
index d846c1fac1..56e504fb54 100644
--- a/gfx/layers/client/TextureRecorded.h
+++ b/gfx/layers/client/TextureRecorded.h
@@ -18,7 +18,8 @@ class RecordedTextureData final : public TextureData {
  public:
   RecordedTextureData(already_AddRefed<CanvasChild> aCanvasChild,
                       gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
-                      TextureType aTextureType);
+                      TextureType aTextureType,
+                      TextureType aWebglTextureType = TextureType::Unknown);
 
   void FillInfo(TextureData::Info& aInfo) const final;
 
diff --git a/gfx/layers/ipc/CanvasChild.cpp b/gfx/layers/ipc/CanvasChild.cpp
index 553217d82b..515463cd8e 100644
--- a/gfx/layers/ipc/CanvasChild.cpp
+++ b/gfx/layers/ipc/CanvasChild.cpp
@@ -7,6 +7,9 @@
 #include "CanvasChild.h"
 
 #include "MainThreadUtils.h"
+#include "mozilla/dom/WorkerPrivate.h"
+#include "mozilla/dom/WorkerRef.h"
+#include "mozilla/dom/WorkerRunnable.h"
 #include "mozilla/gfx/CanvasManagerChild.h"
 #include "mozilla/gfx/DrawTargetRecording.h"
 #include "mozilla/gfx/Tools.h"
@@ -18,6 +21,7 @@
 #include "mozilla/layers/ImageDataSerializer.h"
 #include "mozilla/layers/SourceSurfaceSharedData.h"
 #include "mozilla/Maybe.h"
+#include "mozilla/Mutex.h"
 #include "nsIObserverService.h"
 #include "RecordedCanvasEventImpl.h"
 
@@ -33,9 +37,9 @@ class RecorderHelpers final : public CanvasDrawEventRecorder::Helpers {
 
   ~RecorderHelpers() override = default;
 
-  bool InitTranslator(TextureType aTextureType, gfx::BackendType aBackendType,
-                      Handle&& aReadHandle, nsTArray<Handle>&& aBufferHandles,
-                      uint64_t aBufferSize,
+  bool InitTranslator(TextureType aTextureType, TextureType aWebglTextureType,
+                      gfx::BackendType aBackendType, Handle&& aReadHandle,
+                      nsTArray<Handle>&& aBufferHandles, uint64_t aBufferSize,
                       CrossProcessSemaphoreHandle&& aReaderSem,
                       CrossProcessSemaphoreHandle&& aWriterSem) override {
     NS_ASSERT_OWNINGTHREAD(RecorderHelpers);
@@ -43,7 +47,7 @@ class RecorderHelpers final : public CanvasDrawEventRecorder::Helpers {
       return false;
     }
     return mCanvasChild->SendInitTranslator(
-        aTextureType, aBackendType, std::move(aReadHandle),
+        aTextureType, aWebglTextureType, aBackendType, std::move(aReadHandle),
         std::move(aBufferHandles), aBufferSize, std::move(aReaderSem),
         std::move(aWriterSem));
   }
@@ -165,9 +169,104 @@ class SourceSurfaceCanvasRecording final : public gfx::SourceSurface {
   bool mDetached = false;
 };
 
-CanvasChild::CanvasChild() = default;
+class CanvasDataShmemHolder {
+ public:
+  CanvasDataShmemHolder(ipc::SharedMemoryBasic* aShmem,
+                        CanvasChild* aCanvasChild)
+      : mMutex("CanvasChild::DataShmemHolder::mMutex"),
+        mShmem(aShmem),
+        mCanvasChild(aCanvasChild) {}
+
+  bool Init(dom::ThreadSafeWorkerRef* aWorkerRef) {
+    if (!aWorkerRef) {
+      return true;
+    }
 
-CanvasChild::~CanvasChild() = default;
+    RefPtr<dom::StrongWorkerRef> workerRef = dom::StrongWorkerRef::Create(
+        aWorkerRef->Private(), "CanvasChild::DataShmemHolder",
+        [this]() { DestroyWorker(); });
+    if (NS_WARN_IF(!workerRef)) {
+      return false;
+    }
+
+    MutexAutoLock lock(mMutex);
+    mWorkerRef = new dom::ThreadSafeWorkerRef(workerRef);
+    return true;
+  }
+
+  void Destroy() {
+    class DestroyRunnable final : public dom::WorkerRunnable {
+     public:
+      DestroyRunnable(dom::WorkerPrivate* aWorkerPrivate,
+                      CanvasDataShmemHolder* aShmemHolder)
+          : dom::WorkerRunnable(aWorkerPrivate,
+                                "CanvasDataShmemHolder::Destroy",
+                                dom::WorkerRunnable::WorkerThread),
+            mShmemHolder(aShmemHolder) {}
+
+      bool WorkerRun(JSContext* aCx,
+                     dom::WorkerPrivate* aWorkerPrivate) override {
+        mShmemHolder->Destroy();
+        return true;
+      }
+
+      void PostRun(JSContext* aCx, dom::WorkerPrivate* aWorkerPrivate,
+                   bool aRunResult) override {}
+
+      bool PreDispatch(dom::WorkerPrivate* aWorkerPrivate) override {
+        return true;
+      }
+
+      void PostDispatch(dom::WorkerPrivate* aWorkerPrivate,
+                        bool aDispatchResult) override {}
+
+     private:
+      CanvasDataShmemHolder* mShmemHolder;
+    };
+
+    mMutex.Lock();
+
+    if (mCanvasChild) {
+      if (mWorkerRef) {
+        if (!mWorkerRef->Private()->IsOnCurrentThread()) {
+          auto task = MakeRefPtr<DestroyRunnable>(mWorkerRef->Private(), this);
+          mMutex.Unlock();
+          task->Dispatch();
+          return;
+        }
+      } else if (!NS_IsMainThread()) {
+        mMutex.Unlock();
+        NS_DispatchToMainThread(NS_NewRunnableFunction(
+            "CanvasDataShmemHolder::Destroy", [this]() { Destroy(); }));
+        return;
+      }
+
+      mCanvasChild->ReturnDataSurfaceShmem(mShmem.forget());
+      mCanvasChild = nullptr;
+      mWorkerRef = nullptr;
+    }
+
+    mMutex.Unlock();
+    delete this;
+  }
+
+  void DestroyWorker() {
+    MutexAutoLock lock(mMutex);
+    mCanvasChild = nullptr;
+    mWorkerRef = nullptr;
+  }
+
+ private:
+  Mutex mMutex;
+  RefPtr<ipc::SharedMemoryBasic> mShmem;
+  RefPtr<CanvasChild> mCanvasChild MOZ_GUARDED_BY(mMutex);
+  RefPtr<dom::ThreadSafeWorkerRef> mWorkerRef MOZ_GUARDED_BY(mMutex);
+};
+
+CanvasChild::CanvasChild(dom::ThreadSafeWorkerRef* aWorkerRef)
+    : mWorkerRef(aWorkerRef) {}
+
+CanvasChild::~CanvasChild() { MOZ_ASSERT(!mWorkerRef); }
 
 static void NotifyCanvasDeviceReset() {
   nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
@@ -207,14 +306,15 @@ ipc::IPCResult CanvasChild::RecvBlockCanvas() {
 }
 
 void CanvasChild::EnsureRecorder(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
-                                 TextureType aTextureType) {
+                                 TextureType aTextureType,
+                                 TextureType aWebglTextureType) {
   NS_ASSERT_OWNINGTHREAD(CanvasChild);
 
   if (!mRecorder) {
     gfx::BackendType backendType =
         gfxPlatform::GetPlatform()->GetPreferredCanvasBackend();
-    auto recorder = MakeRefPtr<CanvasDrawEventRecorder>();
-    if (!recorder->Init(aTextureType, backendType,
+    auto recorder = MakeRefPtr<CanvasDrawEventRecorder>(mWorkerRef);
+    if (!recorder->Init(aTextureType, aWebglTextureType, backendType,
                         MakeUnique<RecorderHelpers>(this))) {
       return;
     }
@@ -242,6 +342,8 @@ void CanvasChild::Destroy() {
   if (CanSend()) {
     Send__delete__(this);
   }
+
+  mWorkerRef = nullptr;
 }
 
 bool CanvasChild::EnsureBeginTransaction() {
@@ -397,6 +499,10 @@ already_AddRefed<gfx::DataSourceSurface> CanvasChild::GetDataSurface(
     return nullptr;
   }
 
+  gfx::IntSize ssSize = aSurface->GetSize();
+  gfx::SurfaceFormat ssFormat = aSurface->GetFormat();
+  auto stride = ImageDataSerializer::ComputeRGBStride(ssFormat, ssSize.width);
+
   // Shmem is only valid if the surface is the latest snapshot (not detached).
   if (!aDetached) {
     // If there is a shmem associated with this snapshot id, then we want to try
@@ -411,20 +517,22 @@ already_AddRefed<gfx::DataSourceSurface> CanvasChild::GetDataSurface(
       if (NS_WARN_IF(!mRecorder->WaitForCheckpoint(checkpoint))) {
         return nullptr;
       }
-      gfx::IntSize size = aSurface->GetSize();
-      gfx::SurfaceFormat format = aSurface->GetFormat();
-      auto stride = ImageDataSerializer::ComputeRGBStride(format, size.width);
+      auto* closure =
+          new CanvasDataShmemHolder(it->second.mSnapshotShmem, this);
+      if (NS_WARN_IF(!closure->Init(mWorkerRef))) {
+        delete closure;
+        return nullptr;
+      }
       RefPtr<gfx::DataSourceSurface> dataSurface =
-          gfx::Factory::CreateWrappingDataSourceSurface(shmemPtr, stride, size,
-                                                        format);
+          gfx::Factory::CreateWrappingDataSourceSurface(
+              shmemPtr, stride, ssSize, ssFormat, ReleaseDataShmemHolder,
+              closure);
       return dataSurface.forget();
     }
   }
 
   RecordEvent(RecordedPrepareDataForSurface(aSurface));
 
-  gfx::IntSize ssSize = aSurface->GetSize();
-  gfx::SurfaceFormat ssFormat = aSurface->GetFormat();
   if (!EnsureDataSurfaceShmem(ssSize, ssFormat)) {
     return nullptr;
   }
@@ -435,15 +543,15 @@ already_AddRefed<gfx::DataSourceSurface> CanvasChild::GetDataSurface(
     return nullptr;
   }
 
+  auto* closure = new CanvasDataShmemHolder(mDataSurfaceShmem, this);
+  if (NS_WARN_IF(!closure->Init(mWorkerRef))) {
+    delete closure;
+    return nullptr;
+  }
+
   mDataSurfaceShmemAvailable = false;
-  struct DataShmemHolder {
-    RefPtr<ipc::SharedMemoryBasic> shmem;
-    RefPtr<CanvasChild> canvasChild;
-  };
 
   auto* data = static_cast<uint8_t*>(mDataSurfaceShmem->memory());
-  auto* closure = new DataShmemHolder{do_AddRef(mDataSurfaceShmem), this};
-  auto stride = ImageDataSerializer::ComputeRGBStride(ssFormat, ssSize.width);
 
   RefPtr<gfx::DataSourceSurface> dataSurface =
       gfx::Factory::CreateWrappingDataSourceSurface(
@@ -452,16 +560,8 @@ already_AddRefed<gfx::DataSourceSurface> CanvasChild::GetDataSurface(
 }
 
 /* static */ void CanvasChild::ReleaseDataShmemHolder(void* aClosure) {
-  if (!NS_IsMainThread()) {
-    NS_DispatchToMainThread(NS_NewRunnableFunction(
-        "CanvasChild::ReleaseDataShmemHolder",
-        [aClosure]() { ReleaseDataShmemHolder(aClosure); }));
-    return;
-  }
-
-  auto* shmemHolder = static_cast<DataShmemHolder*>(aClosure);
-  shmemHolder->canvasChild->ReturnDataSurfaceShmem(shmemHolder->shmem.forget());
-  delete shmemHolder;
+  auto* shmemHolder = static_cast<CanvasDataShmemHolder*>(aClosure);
+  shmemHolder->Destroy();
 }
 
 already_AddRefed<gfx::SourceSurface> CanvasChild::WrapSurface(
diff --git a/gfx/layers/ipc/CanvasChild.h b/gfx/layers/ipc/CanvasChild.h
index c99fe50bfb..e22109f406 100644
--- a/gfx/layers/ipc/CanvasChild.h
+++ b/gfx/layers/ipc/CanvasChild.h
@@ -15,6 +15,10 @@
 
 namespace mozilla {
 
+namespace dom {
+class ThreadSafeWorkerRef;
+}
+
 namespace gfx {
 class DrawTargetRecording;
 class SourceSurface;
@@ -28,7 +32,7 @@ class CanvasChild final : public PCanvasChild, public SupportsWeakPtr {
  public:
   NS_INLINE_DECL_REFCOUNTING(CanvasChild)
 
-  CanvasChild();
+  explicit CanvasChild(dom::ThreadSafeWorkerRef* aWorkerRef);
 
   /**
    * @returns true if remote canvas has been deactivated due to failure.
@@ -58,7 +62,7 @@ class CanvasChild final : public PCanvasChild, public SupportsWeakPtr {
    * @params aTextureType the TextureType to create in the CanvasTranslator.
    */
   void EnsureRecorder(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
-                      TextureType aTextureType);
+                      TextureType aTextureType, TextureType aWebglTextureType);
 
   /**
    * Clean up IPDL actor.
@@ -147,6 +151,9 @@ class CanvasChild final : public PCanvasChild, public SupportsWeakPtr {
 
   void CleanupTexture(int64_t aTextureId);
 
+  void ReturnDataSurfaceShmem(
+      already_AddRefed<ipc::SharedMemoryBasic> aDataSurfaceShmem);
+
  protected:
   void ActorDestroy(ActorDestroyReason aWhy) final;
 
@@ -157,14 +164,6 @@ class CanvasChild final : public PCanvasChild, public SupportsWeakPtr {
 
   bool EnsureDataSurfaceShmem(gfx::IntSize aSize, gfx::SurfaceFormat aFormat);
 
-  void ReturnDataSurfaceShmem(
-      already_AddRefed<ipc::SharedMemoryBasic> aDataSurfaceShmem);
-
-  struct DataShmemHolder {
-    RefPtr<ipc::SharedMemoryBasic> shmem;
-    RefPtr<CanvasChild> canvasChild;
-  };
-
   static void ReleaseDataShmemHolder(void* aClosure);
 
   void DropFreeBuffersWhenDormant();
@@ -173,6 +172,7 @@ class CanvasChild final : public PCanvasChild, public SupportsWeakPtr {
 
   static bool mDeactivated;
 
+  RefPtr<dom::ThreadSafeWorkerRef> mWorkerRef;
   RefPtr<CanvasDrawEventRecorder> mRecorder;
 
   RefPtr<ipc::SharedMemoryBasic> mDataSurfaceShmem;
diff --git a/gfx/layers/ipc/CanvasTranslator.cpp b/gfx/layers/ipc/CanvasTranslator.cpp
index 08150d6952..4a184f48d8 100644
--- a/gfx/layers/ipc/CanvasTranslator.cpp
+++ b/gfx/layers/ipc/CanvasTranslator.cpp
@@ -13,6 +13,7 @@
 #include "mozilla/gfx/DrawTargetWebgl.h"
 #include "mozilla/gfx/gfxVars.h"
 #include "mozilla/gfx/GPUParent.h"
+#include "mozilla/gfx/GPUProcessManager.h"
 #include "mozilla/gfx/Logging.h"
 #include "mozilla/ipc/Endpoint.h"
 #include "mozilla/layers/BufferTexture.h"
@@ -131,15 +132,17 @@ bool CanvasTranslator::EnsureSharedContextWebgl() {
 }
 
 mozilla::ipc::IPCResult CanvasTranslator::RecvInitTranslator(
-    TextureType aTextureType, gfx::BackendType aBackendType,
-    Handle&& aReadHandle, nsTArray<Handle>&& aBufferHandles,
-    uint64_t aBufferSize, CrossProcessSemaphoreHandle&& aReaderSem,
+    TextureType aTextureType, TextureType aWebglTextureType,
+    gfx::BackendType aBackendType, Handle&& aReadHandle,
+    nsTArray<Handle>&& aBufferHandles, uint64_t aBufferSize,
+    CrossProcessSemaphoreHandle&& aReaderSem,
     CrossProcessSemaphoreHandle&& aWriterSem) {
   if (mHeaderShmem) {
     return IPC_FAIL(this, "RecvInitTranslator called twice.");
   }
 
   mTextureType = aTextureType;
+  mWebglTextureType = aWebglTextureType;
   mBackendType = aBackendType;
   mOtherPid = OtherPid();
 
@@ -637,7 +640,11 @@ bool CanvasTranslator::HandleExtensionEvent(int32_t aType) {
   }
 }
 
-void CanvasTranslator::BeginTransaction() { mIsInTransaction = true; }
+void CanvasTranslator::BeginTransaction() {
+  PROFILER_MARKER_TEXT("CanvasTranslator", GRAPHICS, {},
+                       "CanvasTranslator::BeginTransaction"_ns);
+  mIsInTransaction = true;
+}
 
 void CanvasTranslator::Flush() {
 #if defined(XP_WIN)
@@ -728,9 +735,15 @@ bool CanvasTranslator::CheckForFreshCanvasDevice(int aLineNumber) {
     NotifyDeviceChanged();
   }
 
-  RefPtr<Runnable> runnable = NS_NewRunnableFunction(
-      "CanvasTranslator NotifyDeviceReset",
-      []() { gfx::GPUParent::GetSingleton()->NotifyDeviceReset(); });
+  RefPtr<Runnable> runnable =
+      NS_NewRunnableFunction("CanvasTranslator NotifyDeviceReset", []() {
+        if (XRE_IsGPUProcess()) {
+          gfx::GPUParent::GetSingleton()->NotifyDeviceReset();
+        } else {
+          gfx::GPUProcessManager::Get()->OnInProcessDeviceReset(
+              /* aTrackThreshold */ false);
+        }
+      });
 
   // It is safe to wait here because only the Compositor thread waits on us and
   // the main thread doesn't wait on the compositor thread in the GPU process.
@@ -1025,6 +1038,8 @@ bool CanvasTranslator::UnlockTexture(int64_t aTextureId) {
 }
 
 bool CanvasTranslator::PresentTexture(int64_t aTextureId, RemoteTextureId aId) {
+  AUTO_PROFILER_MARKER_TEXT("CanvasTranslator", GRAPHICS, {},
+                            "CanvasTranslator::PresentTexture"_ns);
   auto result = mTextureInfo.find(aTextureId);
   if (result == mTextureInfo.end()) {
     return false;
@@ -1033,7 +1048,8 @@ bool CanvasTranslator::PresentTexture(int64_t aTextureId, RemoteTextureId aId) {
   RemoteTextureOwnerId ownerId = info.mRemoteTextureOwnerId;
   if (gfx::DrawTargetWebgl* webgl = info.GetDrawTargetWebgl()) {
     EnsureRemoteTextureOwner(ownerId);
-    if (webgl->CopyToSwapChain(aId, ownerId, mRemoteTextureOwner)) {
+    if (webgl->CopyToSwapChain(mWebglTextureType, aId, ownerId,
+                               mRemoteTextureOwner)) {
       return true;
     }
     if (mSharedContext && mSharedContext->IsContextLost()) {
diff --git a/gfx/layers/ipc/CanvasTranslator.h b/gfx/layers/ipc/CanvasTranslator.h
index cf87b7ab53..5258e0c529 100644
--- a/gfx/layers/ipc/CanvasTranslator.h
+++ b/gfx/layers/ipc/CanvasTranslator.h
@@ -69,6 +69,7 @@ class CanvasTranslator final : public gfx::InlineTranslator,
    * CanvasEventRingBuffer.
    *
    * @param aTextureType the TextureType the translator will create
+   * @param aWebglTextureType the TextureType of any WebGL buffers
    * @param aBackendType the BackendType for texture data
    * @param aHeaderHandle handle for the control header
    * @param aBufferHandles handles for the initial buffers for translation
@@ -77,6 +78,7 @@ class CanvasTranslator final : public gfx::InlineTranslator,
    * @param aWriterSem writing blocked semaphore for the CanvasEventRingBuffer
    */
   ipc::IPCResult RecvInitTranslator(TextureType aTextureType,
+                                    TextureType aWebglTextureType,
                                     gfx::BackendType aBackendType,
                                     Handle&& aReadHandle,
                                     nsTArray<Handle>&& aBufferHandles,
@@ -358,6 +360,7 @@ class CanvasTranslator final : public gfx::InlineTranslator,
   UniquePtr<CrossProcessSemaphore> mWriterSemaphore;
   UniquePtr<CrossProcessSemaphore> mReaderSemaphore;
   TextureType mTextureType = TextureType::Unknown;
+  TextureType mWebglTextureType = TextureType::Unknown;
   UniquePtr<TextureData> mReferenceTextureData;
   dom::ContentParentId mContentId;
   uint32_t mManagerId;
diff --git a/gfx/layers/ipc/CompositorManagerChild.cpp b/gfx/layers/ipc/CompositorManagerChild.cpp
index 0e553745d3..8d89339373 100644
--- a/gfx/layers/ipc/CompositorManagerChild.cpp
+++ b/gfx/layers/ipc/CompositorManagerChild.cpp
@@ -10,6 +10,7 @@
 #include "mozilla/layers/CompositorBridgeChild.h"
 #include "mozilla/layers/CompositorManagerParent.h"
 #include "mozilla/layers/CompositorThread.h"
+#include "mozilla/gfx/CanvasShutdownManager.h"
 #include "mozilla/gfx/gfxVars.h"
 #include "mozilla/gfx/GPUProcessManager.h"
 #include "mozilla/dom/ContentChild.h"  // for ContentChild
@@ -67,7 +68,15 @@ bool CompositorManagerChild::Init(Endpoint<PCompositorManagerChild>&& aEndpoint,
   sInstance = new CompositorManagerChild(std::move(aEndpoint), aProcessToken,
                                          aNamespace);
   sOtherPid = sInstance->OtherPid();
-  return sInstance->CanSend();
+  if (!sInstance->CanSend()) {
+    return false;
+  }
+
+  // If there are any canvases waiting on the recreation of the GPUProcess or
+  // CompositorManagerChild, then we need to notify them so that they can
+  // restore their contexts.
+  gfx::CanvasShutdownManager::OnCompositorManagerRestored();
+  return true;
 }
 
 /* static */
diff --git a/gfx/layers/ipc/LayersMessageUtils.h b/gfx/layers/ipc/LayersMessageUtils.h
index d869d4ed83..a4e9557ac3 100644
--- a/gfx/layers/ipc/LayersMessageUtils.h
+++ b/gfx/layers/ipc/LayersMessageUtils.h
@@ -520,7 +520,7 @@ template <>
 struct ParamTraits<mozilla::ScrollUpdateType>
     : public ContiguousEnumSerializerInclusive<
           mozilla::ScrollUpdateType, mozilla::ScrollUpdateType::Absolute,
-          mozilla::ScrollUpdateType::MergeableAbsolute> {};
+          mozilla::ScrollUpdateType::PureRelative> {};
 
 template <>
 struct ParamTraits<mozilla::ScrollMode>
diff --git a/gfx/layers/ipc/PCanvas.ipdl b/gfx/layers/ipc/PCanvas.ipdl
index 5187e61d23..59896b72cf 100644
--- a/gfx/layers/ipc/PCanvas.ipdl
+++ b/gfx/layers/ipc/PCanvas.ipdl
@@ -32,9 +32,9 @@ parent:
    * each aBufferHandles' memory and the default size. aReaderSem and aWriterSem
    * are handles for the semaphores to handle waiting on either side.
    */
-  async InitTranslator(TextureType aTextureType, BackendType aBackendType,
-                       Handle aHeaderHandle, Handle[] aBufferHandles,
-                       uint64_t aBufferSize,
+  async InitTranslator(TextureType aTextureType, TextureType aWebglTextureType,
+                       BackendType aBackendType, Handle aHeaderHandle,
+                       Handle[] aBufferHandles, uint64_t aBufferSize,
                        CrossProcessSemaphoreHandle aReaderSem,
                        CrossProcessSemaphoreHandle aWriterSem);
 
diff --git a/gfx/layers/ipc/VideoBridgeParent.cpp b/gfx/layers/ipc/VideoBridgeParent.cpp
index 6413c27bc1..50f0549e50 100644
--- a/gfx/layers/ipc/VideoBridgeParent.cpp
+++ b/gfx/layers/ipc/VideoBridgeParent.cpp
@@ -17,9 +17,8 @@ namespace mozilla::layers {
 using namespace mozilla::ipc;
 using namespace mozilla::gfx;
 
-using VideoBridgeTable =
-    EnumeratedArray<VideoBridgeSource, VideoBridgeSource::_Count,
-                    VideoBridgeParent*>;
+using VideoBridgeTable = EnumeratedArray<VideoBridgeSource, VideoBridgeParent*,
+                                         size_t(VideoBridgeSource::_Count)>;
 
 static StaticDataMutex<VideoBridgeTable> sVideoBridgeFromProcess(
     "VideoBridges");
diff --git a/gfx/layers/moz.build b/gfx/layers/moz.build
index 1bf2e83804..384611b68b 100644
--- a/gfx/layers/moz.build
+++ b/gfx/layers/moz.build
@@ -260,7 +260,7 @@ if CONFIG["MOZ_WAYLAND"]:
         "SurfacePoolWayland.cpp",
     ]
 
-if CONFIG["MOZ_WIDGET_TOOLKIT"] == "cocoa":
+if CONFIG["MOZ_WIDGET_TOOLKIT"] in ("cocoa", "uikit"):
     EXPORTS.mozilla.layers += [
         "NativeLayerCA.h",
         "SurfacePoolCA.h",
@@ -458,7 +458,7 @@ DEFINES["GOOGLE_PROTOBUF_NO_RTTI"] = True
 DEFINES["GOOGLE_PROTOBUF_NO_STATIC_INITIALIZER"] = True
 DEFINES["MOZ_APP_VERSION"] = CONFIG["MOZ_APP_VERSION"]
 
-if CONFIG["MOZ_WIDGET_TOOLKIT"] == "cocoa":
+if CONFIG["MOZ_WIDGET_TOOLKIT"] in ("cocoa", "uikit"):
     SOURCES += [
         "opengl/MacIOSurfaceTextureClientOGL.cpp",
         "opengl/MacIOSurfaceTextureHostOGL.cpp",
diff --git a/gfx/layers/opengl/MacIOSurfaceTextureHostOGL.cpp b/gfx/layers/opengl/MacIOSurfaceTextureHostOGL.cpp
index ee61045599..112ed7711c 100644
--- a/gfx/layers/opengl/MacIOSurfaceTextureHostOGL.cpp
+++ b/gfx/layers/opengl/MacIOSurfaceTextureHostOGL.cpp
@@ -10,7 +10,6 @@
 #include "mozilla/webrender/RenderMacIOSurfaceTextureHost.h"
 #include "mozilla/webrender/RenderThread.h"
 #include "mozilla/webrender/WebRenderAPI.h"
-#include "GLContextCGL.h"
 
 namespace mozilla {
 namespace layers {
diff --git a/gfx/layers/wr/AsyncImagePipelineManager.cpp b/gfx/layers/wr/AsyncImagePipelineManager.cpp
index 464b8fb69f..8a49ffef69 100644
--- a/gfx/layers/wr/AsyncImagePipelineManager.cpp
+++ b/gfx/layers/wr/AsyncImagePipelineManager.cpp
@@ -229,8 +229,7 @@ Maybe<TextureHost::ResourceUpdateOp> AsyncImagePipelineManager::UpdateImageKeys(
   auto* wrapper = aTexture ? aTexture->AsRemoteTextureHostWrapper() : nullptr;
   if (wrapper && !aPipeline->mImageHost->GetAsyncRef()) {
     std::function<void(const RemoteTextureInfo&)> function;
-    RemoteTextureMap::Get()->GetRemoteTexture(
-        wrapper, std::move(function), /* aWaitForRemoteTextureOwner */ false);
+    RemoteTextureMap::Get()->GetRemoteTexture(wrapper, std::move(function));
   }
 
   if (!aTexture || aTexture->NumSubTextures() == 0) {
diff --git a/gfx/layers/wr/WebRenderBridgeParent.cpp b/gfx/layers/wr/WebRenderBridgeParent.cpp
index 789476cb6b..83139b6af6 100644
--- a/gfx/layers/wr/WebRenderBridgeParent.cpp
+++ b/gfx/layers/wr/WebRenderBridgeParent.cpp
@@ -141,7 +141,7 @@ void gfx_wr_set_crash_annotation(mozilla::wr::CrashAnnotation aAnnotation,
     return;
   }
 
-  CrashReporter::AnnotateCrashReport(annotation, nsDependentCString(aValue));
+  CrashReporter::RecordAnnotationCString(annotation, aValue);
 }
 
 void gfx_wr_clear_crash_annotation(mozilla::wr::CrashAnnotation aAnnotation) {
@@ -150,7 +150,7 @@ void gfx_wr_clear_crash_annotation(mozilla::wr::CrashAnnotation aAnnotation) {
     return;
   }
 
-  CrashReporter::RemoveCrashReportAnnotation(annotation);
+  CrashReporter::UnrecordAnnotation(annotation);
 }
 }
 
@@ -1188,7 +1188,8 @@ mozilla::ipc::IPCResult WebRenderBridgeParent::RecvSetDisplayList(
       IsRootWebRenderBridgeParent());
 
   if (!IsRootWebRenderBridgeParent()) {
-    CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::URL, aTxnURL);
+    CrashReporter::RecordAnnotationNSCString(CrashReporter::Annotation::URL,
+                                             aTxnURL);
   }
 
   CompositorBridgeParent* cbp = GetRootCompositorBridgeParent();
@@ -1330,7 +1331,8 @@ mozilla::ipc::IPCResult WebRenderBridgeParent::RecvEmptyTransaction(
       IsRootWebRenderBridgeParent());
 
   if (!IsRootWebRenderBridgeParent()) {
-    CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::URL, aTxnURL);
+    CrashReporter::RecordAnnotationNSCString(CrashReporter::Annotation::URL,
+                                             aTxnURL);
   }
 
   AUTO_PROFILER_TRACING_MARKER("Paint", "EmptyTransaction", GRAPHICS);
diff --git a/gfx/layers/wr/WebRenderImageHost.cpp b/gfx/layers/wr/WebRenderImageHost.cpp
index e3bbd5d50f..5016bc30f8 100644
--- a/gfx/layers/wr/WebRenderImageHost.cpp
+++ b/gfx/layers/wr/WebRenderImageHost.cpp
@@ -198,8 +198,11 @@ void WebRenderImageHost::UseRemoteTexture() {
     while (!mPendingRemoteTextureWrappers.empty()) {
       auto* wrapper =
           mPendingRemoteTextureWrappers.front()->AsRemoteTextureHostWrapper();
-      mWaitingReadyCallback = RemoteTextureMap::Get()->GetRemoteTexture(
-          wrapper, readyCallback, mWaitForRemoteTextureOwner);
+      if (mWaitForRemoteTextureOwner) {
+        RemoteTextureMap::Get()->WaitForRemoteTextureOwner(wrapper);
+      }
+      mWaitingReadyCallback =
+          RemoteTextureMap::Get()->GetRemoteTexture(wrapper, readyCallback);
       MOZ_ASSERT_IF(mWaitingReadyCallback, !wrapper->IsReadyForRendering());
       if (!wrapper->IsReadyForRendering()) {
         break;
@@ -213,9 +216,9 @@ void WebRenderImageHost::UseRemoteTexture() {
     mPendingRemoteTextureWrappers.pop_front();
     MOZ_ASSERT(mPendingRemoteTextureWrappers.empty());
 
-    std::function<void(const RemoteTextureInfo&)> function;
-    RemoteTextureMap::Get()->GetRemoteTexture(wrapper, std::move(function),
-                                              mWaitForRemoteTextureOwner);
+    if (mWaitForRemoteTextureOwner) {
+      RemoteTextureMap::Get()->WaitForRemoteTextureOwner(wrapper);
+    }
     mWaitForRemoteTextureOwner = false;
   }
 
diff --git a/gfx/layers/wr/WebRenderScrollData.cpp b/gfx/layers/wr/WebRenderScrollData.cpp
index 538df8bdef..905b7e1de0 100644
--- a/gfx/layers/wr/WebRenderScrollData.cpp
+++ b/gfx/layers/wr/WebRenderScrollData.cpp
@@ -370,6 +370,22 @@ void WebRenderScrollData::ApplyUpdates(ScrollUpdatesMap&& aUpdates,
   mPaintSequenceNumber = aPaintSequenceNumber;
 }
 
+void WebRenderScrollData::PrependUpdates(
+    const WebRenderScrollData& aPreviousData) {
+  for (auto previousMetadata : aPreviousData.mScrollMetadatas) {
+    const nsTArray<ScrollPositionUpdate>& previousUpdates =
+        previousMetadata.GetScrollUpdates();
+    if (previousUpdates.IsEmpty()) {
+      continue;
+    }
+
+    if (Maybe<size_t> index =
+            HasMetadataFor(previousMetadata.GetMetrics().GetScrollId())) {
+      mScrollMetadatas[*index].PrependUpdates(previousUpdates);
+    }
+  }
+}
+
 void WebRenderScrollData::DumpSubtree(std::ostream& aOut, size_t aIndex,
                                       const std::string& aIndent) const {
   aOut << aIndent;
diff --git a/gfx/layers/wr/WebRenderScrollData.h b/gfx/layers/wr/WebRenderScrollData.h
index c575d4ca21..fd82ac93fc 100644
--- a/gfx/layers/wr/WebRenderScrollData.h
+++ b/gfx/layers/wr/WebRenderScrollData.h
@@ -276,6 +276,13 @@ class WebRenderScrollData {
 
   void ApplyUpdates(ScrollUpdatesMap&& aUpdates, uint32_t aPaintSequenceNumber);
 
+  // Prepend the scroll position updates in the previous data to this data so
+  // that we can handle all scroll position updates in the proper order.
+  void PrependUpdates(const WebRenderScrollData& aPreviousData);
+
+  void SetWasUpdateSkipped() { mWasUpdateSkipped = true; }
+  bool GetWasUpdateSkipped() const { return mWasUpdateSkipped; }
+
   friend struct IPC::ParamTraits<WebRenderScrollData>;
 
   friend std::ostream& operator<<(std::ostream& aOut,
@@ -328,6 +335,12 @@ class WebRenderScrollData {
 
   bool mIsFirstPaint;
   uint32_t mPaintSequenceNumber;
+
+  // Wether this data was skipped to updated because the parent process hasn't
+  // yet gotten the referent LayersId for this data.
+  //
+  // Note this variable is not copied over IPC.
+  bool mWasUpdateSkipped = false;
 };
 
 }  // namespace layers