From 36d22d82aa202bb199967e9512281e9a53db42c9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 7 Apr 2024 21:33:14 +0200
Subject: Adding upstream version 115.7.0esr.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 layout/style/ImageLoader.cpp | 827 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 827 insertions(+)
 create mode 100644 layout/style/ImageLoader.cpp

(limited to 'layout/style/ImageLoader.cpp')

diff --git a/layout/style/ImageLoader.cpp b/layout/style/ImageLoader.cpp
new file mode 100644
index 0000000000..af3e923053
--- /dev/null
+++ b/layout/style/ImageLoader.cpp
@@ -0,0 +1,827 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A class that handles style system image loads (other image loads are handled
+ * by the nodes in the content tree).
+ */
+
+#include "mozilla/css/ImageLoader.h"
+
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include "mozilla/dom/ImageTracker.h"
+#include "nsContentUtils.h"
+#include "nsIReflowCallback.h"
+#include "nsLayoutUtils.h"
+#include "nsError.h"
+#include "nsCanvasFrame.h"
+#include "nsDisplayList.h"
+#include "nsIFrameInlines.h"
+#include "imgIContainer.h"
+#include "imgINotificationObserver.h"
+#include "Image.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/SVGObserverUtils.h"
+#include "mozilla/layers/WebRenderUserData.h"
+#include "nsTHashSet.h"
+
+using namespace mozilla::dom;
+
+namespace mozilla::css {
+
+// This is a singleton observer which looks in the `GlobalRequestTable` to look
+// at which loaders to notify.
+struct GlobalImageObserver final : public imgINotificationObserver {
+  NS_DECL_ISUPPORTS
+  NS_DECL_IMGINOTIFICATIONOBSERVER
+
+  GlobalImageObserver() = default;
+
+ private:
+  virtual ~GlobalImageObserver() = default;
+};
+
+NS_IMPL_ADDREF(GlobalImageObserver)
+NS_IMPL_RELEASE(GlobalImageObserver)
+
+NS_INTERFACE_MAP_BEGIN(GlobalImageObserver)
+  NS_INTERFACE_MAP_ENTRY(imgINotificationObserver)
+NS_INTERFACE_MAP_END
+
+// Data associated with every started load.
+struct ImageTableEntry {
+  // Set of all ImageLoaders that have registered this URL and care for updates
+  // for it.
+  nsTHashSet<ImageLoader*> mImageLoaders;
+
+  // The amount of style values that are sharing this image.
+  uint32_t mSharedCount = 1;
+};
+
+using GlobalRequestTable =
+    nsClassHashtable<nsRefPtrHashKey<imgIRequest>, ImageTableEntry>;
+
+// A table of all loads, keyed by their id mapping them to the set of
+// ImageLoaders they have been registered in, and recording their "canonical"
+// image request.
+//
+// We use the load id as the key since we can only access sImages on the
+// main thread, but LoadData objects might be destroyed from other threads,
+// and we don't want to leave dangling pointers around.
+static StaticAutoPtr<GlobalRequestTable> sImages;
+static StaticRefPtr<GlobalImageObserver> sImageObserver;
+
+/* static */
+void ImageLoader::Init() {
+  sImages = new GlobalRequestTable();
+  sImageObserver = new GlobalImageObserver();
+}
+
+/* static */
+void ImageLoader::Shutdown() {
+  for (const auto& entry : *sImages) {
+    imgIRequest* imgRequest = entry.GetKey();
+    // All the images we put in sImages are imgRequestProxy, see LoadImage, but
+    // it's non-trivial to make the hash table to use that without changing a
+    // lot of other code.
+    auto* req = static_cast<imgRequestProxy*>(imgRequest);
+    req->SetCancelable(true);
+    req->CancelAndForgetObserver(NS_BINDING_ABORTED);
+  }
+
+  sImages = nullptr;
+  sImageObserver = nullptr;
+}
+
+void ImageLoader::DropDocumentReference() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // It's okay if GetPresContext returns null here (due to the presshell pointer
+  // on the document being null) as that means the presshell has already
+  // been destroyed, and it also calls ClearFrames when it is destroyed.
+  ClearFrames(GetPresContext());
+
+  mDocument = nullptr;
+}
+
+// Arrays of requests and frames are sorted by their pointer address,
+// for faster lookup.
+template <typename Elem, typename Item,
+          typename Comparator = nsDefaultComparator<Elem, Item>>
+static size_t GetMaybeSortedIndex(const nsTArray<Elem>& aArray,
+                                  const Item& aItem, bool* aFound,
+                                  Comparator aComparator = Comparator()) {
+  size_t index = aArray.IndexOfFirstElementGt(aItem, aComparator);
+  *aFound = index > 0 && aComparator.Equals(aItem, aArray.ElementAt(index - 1));
+  return index;
+}
+
+// Returns true if an async decode is triggered for aRequest, and thus we will
+// get an OnFrameComplete callback for this request eventually.
+static bool TriggerAsyncDecodeAtIntrinsicSize(imgIRequest* aRequest) {
+  uint32_t status = 0;
+  // Don't block onload if we've already got a frame complete status
+  // (since in that case the image is already loaded), or if we get an
+  // error status (since then we know the image won't ever load).
+  if (NS_SUCCEEDED(aRequest->GetImageStatus(&status))) {
+    if (status & imgIRequest::STATUS_FRAME_COMPLETE) {
+      // Already decoded, no need to do it again.
+      return false;
+    }
+    if (status & imgIRequest::STATUS_ERROR) {
+      // Already errored, this would be useless.
+      return false;
+    }
+  }
+
+  // We want to request decode in such a way that avoids triggering sync decode.
+  // First, we attempt to convert the aRequest into a imgIContainer. If that
+  // succeeds, then aRequest has an image and we can request decoding for size
+  // at zero size, the size will be ignored because we don't pass the
+  // FLAG_HIGH_QUALITY_SCALING flag and an async decode (because we didn't pass
+  // any sync decoding flags) at the intrinsic size will be requested. If the
+  // conversion to imgIContainer is unsuccessful, then that means aRequest
+  // doesn't have an image yet, which means we can safely call StartDecoding()
+  // on it without triggering any synchronous work.
+  nsCOMPtr<imgIContainer> imgContainer;
+  aRequest->GetImage(getter_AddRefs(imgContainer));
+  if (imgContainer) {
+    imgContainer->RequestDecodeForSize(gfx::IntSize(0, 0),
+                                       imgIContainer::DECODE_FLAGS_DEFAULT);
+  } else {
+    // It's safe to call StartDecoding directly, since it can't
+    // trigger synchronous decode without an image. Flags are ignored.
+    aRequest->StartDecoding(imgIContainer::FLAG_NONE);
+  }
+  return true;
+}
+
+void ImageLoader::AssociateRequestToFrame(imgIRequest* aRequest,
+                                          nsIFrame* aFrame, Flags aFlags) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!(aFlags & Flags::IsBlockingLoadEvent),
+             "Shouldn't be used in the public API");
+
+  {
+    nsCOMPtr<imgINotificationObserver> observer;
+    aRequest->GetNotificationObserver(getter_AddRefs(observer));
+    if (!observer) {
+      // The request has already been canceled, so ignore it. This is ok because
+      // we're not going to get any more notifications from a canceled request.
+      return;
+    }
+    MOZ_ASSERT(observer == sImageObserver);
+  }
+
+  auto* const frameSet =
+      mRequestToFrameMap
+          .LookupOrInsertWith(
+              aRequest,
+              [&] {
+                mDocument->ImageTracker()->Add(aRequest);
+
+                if (auto entry = sImages->Lookup(aRequest)) {
+                  DebugOnly<bool> inserted =
+                      entry.Data()->mImageLoaders.EnsureInserted(this);
+                  MOZ_ASSERT(inserted);
+                } else {
+                  MOZ_ASSERT_UNREACHABLE(
+                      "Shouldn't be associating images not in sImages");
+                }
+
+                if (nsPresContext* presContext = GetPresContext()) {
+                  nsLayoutUtils::RegisterImageRequestIfAnimated(
+                      presContext, aRequest, nullptr);
+                }
+                return MakeUnique<FrameSet>();
+              })
+          .get();
+
+  auto* const requestSet =
+      mFrameToRequestMap
+          .LookupOrInsertWith(aFrame,
+                              [=]() {
+                                aFrame->SetHasImageRequest(true);
+                                return MakeUnique<RequestSet>();
+                              })
+          .get();
+
+  // Add frame to the frameSet, and handle any special processing the
+  // frame might require.
+  FrameWithFlags fwf(aFrame);
+  FrameWithFlags* fwfToModify = &fwf;
+
+  // See if the frameSet already has this frame.
+  bool found;
+  uint32_t i =
+      GetMaybeSortedIndex(*frameSet, fwf, &found, FrameOnlyComparator());
+  if (found) {
+    // We're already tracking this frame, so prepare to modify the
+    // existing FrameWithFlags object.
+    fwfToModify = &frameSet->ElementAt(i - 1);
+  }
+
+  // Check if the frame requires special processing.
+  if (aFlags & Flags::RequiresReflowOnSizeAvailable) {
+    MOZ_ASSERT(!(aFlags &
+                 Flags::RequiresReflowOnFirstFrameCompleteAndLoadEventBlocking),
+               "These two are exclusive");
+    fwfToModify->mFlags |= Flags::RequiresReflowOnSizeAvailable;
+  }
+
+  if (aFlags & Flags::RequiresReflowOnFirstFrameCompleteAndLoadEventBlocking) {
+    fwfToModify->mFlags |=
+        Flags::RequiresReflowOnFirstFrameCompleteAndLoadEventBlocking;
+
+    // If we weren't already blocking onload, do that now.
+    if (!(fwfToModify->mFlags & Flags::IsBlockingLoadEvent)) {
+      if (TriggerAsyncDecodeAtIntrinsicSize(aRequest)) {
+        // If there's no error, and the image has not loaded yet, so we can
+        // block onload.
+        fwfToModify->mFlags |= Flags::IsBlockingLoadEvent;
+
+        // Block document onload until we either remove the frame in
+        // RemoveRequestToFrameMapping or onLoadComplete, or complete a reflow.
+        mDocument->BlockOnload();
+      }
+    }
+  }
+
+  // Do some sanity checking to ensure that we only add to one mapping
+  // iff we also add to the other mapping.
+  DebugOnly<bool> didAddToFrameSet(false);
+  DebugOnly<bool> didAddToRequestSet(false);
+
+  // If we weren't already tracking this frame, add it to the frameSet.
+  if (!found) {
+    frameSet->InsertElementAt(i, fwf);
+    didAddToFrameSet = true;
+  }
+
+  // Add request to the request set if it wasn't already there.
+  i = GetMaybeSortedIndex(*requestSet, aRequest, &found);
+  if (!found) {
+    requestSet->InsertElementAt(i, aRequest);
+    didAddToRequestSet = true;
+  }
+
+  MOZ_ASSERT(didAddToFrameSet == didAddToRequestSet,
+             "We should only add to one map iff we also add to the other map.");
+}
+
+void ImageLoader::RemoveRequestToFrameMapping(imgIRequest* aRequest,
+                                              nsIFrame* aFrame) {
+#ifdef DEBUG
+  {
+    nsCOMPtr<imgINotificationObserver> observer;
+    aRequest->GetNotificationObserver(getter_AddRefs(observer));
+    MOZ_ASSERT(!observer || observer == sImageObserver);
+  }
+#endif
+
+  if (auto entry = mRequestToFrameMap.Lookup(aRequest)) {
+    const auto& frameSet = entry.Data();
+    MOZ_ASSERT(frameSet, "This should never be null");
+
+    // Before we remove aFrame from the frameSet, unblock onload if needed.
+    bool found;
+    uint32_t i = GetMaybeSortedIndex(*frameSet, FrameWithFlags(aFrame), &found,
+                                     FrameOnlyComparator());
+    if (found) {
+      UnblockOnloadIfNeeded(frameSet->ElementAt(i - 1));
+      frameSet->RemoveElementAt(i - 1);
+    }
+
+    if (frameSet->IsEmpty()) {
+      DeregisterImageRequest(aRequest, GetPresContext());
+      entry.Remove();
+    }
+  }
+}
+
+void ImageLoader::DeregisterImageRequest(imgIRequest* aRequest,
+                                         nsPresContext* aPresContext) {
+  mDocument->ImageTracker()->Remove(aRequest);
+
+  if (auto entry = sImages->Lookup(aRequest)) {
+    entry.Data()->mImageLoaders.EnsureRemoved(this);
+  }
+
+  if (aPresContext) {
+    nsLayoutUtils::DeregisterImageRequest(aPresContext, aRequest, nullptr);
+  }
+}
+
+void ImageLoader::RemoveFrameToRequestMapping(imgIRequest* aRequest,
+                                              nsIFrame* aFrame) {
+  if (auto entry = mFrameToRequestMap.Lookup(aFrame)) {
+    const auto& requestSet = entry.Data();
+    MOZ_ASSERT(requestSet, "This should never be null");
+    requestSet->RemoveElementSorted(aRequest);
+    if (requestSet->IsEmpty()) {
+      aFrame->SetHasImageRequest(false);
+      entry.Remove();
+    }
+  }
+}
+
+void ImageLoader::DisassociateRequestFromFrame(imgIRequest* aRequest,
+                                               nsIFrame* aFrame) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aFrame->HasImageRequest(), "why call me?");
+
+  RemoveRequestToFrameMapping(aRequest, aFrame);
+  RemoveFrameToRequestMapping(aRequest, aFrame);
+}
+
+void ImageLoader::DropRequestsForFrame(nsIFrame* aFrame) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aFrame->HasImageRequest(), "why call me?");
+
+  UniquePtr<RequestSet> requestSet;
+  mFrameToRequestMap.Remove(aFrame, &requestSet);
+  aFrame->SetHasImageRequest(false);
+  if (MOZ_UNLIKELY(!requestSet)) {
+    MOZ_ASSERT_UNREACHABLE("HasImageRequest was lying");
+    return;
+  }
+  for (imgIRequest* request : *requestSet) {
+    RemoveRequestToFrameMapping(request, aFrame);
+  }
+}
+
+void ImageLoader::SetAnimationMode(uint16_t aMode) {
+  MOZ_ASSERT(NS_IsMainThread());
+  NS_ASSERTION(aMode == imgIContainer::kNormalAnimMode ||
+                   aMode == imgIContainer::kDontAnimMode ||
+                   aMode == imgIContainer::kLoopOnceAnimMode,
+               "Wrong Animation Mode is being set!");
+
+  for (nsISupports* key : mRequestToFrameMap.Keys()) {
+    auto* request = static_cast<imgIRequest*>(key);
+
+#ifdef DEBUG
+    {
+      nsCOMPtr<imgIRequest> debugRequest = request;
+      NS_ASSERTION(debugRequest == request, "This is bad");
+    }
+#endif
+
+    nsCOMPtr<imgIContainer> container;
+    request->GetImage(getter_AddRefs(container));
+    if (!container) {
+      continue;
+    }
+
+    // This can fail if the image is in error, and we don't care.
+    container->SetAnimationMode(aMode);
+  }
+}
+
+void ImageLoader::ClearFrames(nsPresContext* aPresContext) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  for (const auto& key : mRequestToFrameMap.Keys()) {
+    auto* request = static_cast<imgIRequest*>(key);
+
+#ifdef DEBUG
+    {
+      nsCOMPtr<imgIRequest> debugRequest = request;
+      NS_ASSERTION(debugRequest == request, "This is bad");
+    }
+#endif
+
+    DeregisterImageRequest(request, aPresContext);
+  }
+
+  mRequestToFrameMap.Clear();
+  mFrameToRequestMap.Clear();
+}
+
+static CORSMode EffectiveCorsMode(nsIURI* aURI,
+                                  const StyleComputedImageUrl& aImage) {
+  MOZ_ASSERT(aURI);
+  StyleCorsMode mode = aImage.CorsMode();
+  if (mode == StyleCorsMode::None) {
+    return CORSMode::CORS_NONE;
+  }
+  MOZ_ASSERT(mode == StyleCorsMode::Anonymous);
+  if (aURI->SchemeIs("resource")) {
+    return CORSMode::CORS_NONE;
+  }
+  return CORSMode::CORS_ANONYMOUS;
+}
+
+/* static */
+already_AddRefed<imgRequestProxy> ImageLoader::LoadImage(
+    const StyleComputedImageUrl& aImage, Document& aDocument) {
+  MOZ_ASSERT(NS_IsMainThread());
+  nsIURI* uri = aImage.GetURI();
+  if (!uri) {
+    return nullptr;
+  }
+
+  if (aImage.HasRef()) {
+    bool isEqualExceptRef = false;
+    nsIURI* docURI = aDocument.GetDocumentURI();
+    if (NS_SUCCEEDED(uri->EqualsExceptRef(docURI, &isEqualExceptRef)) &&
+        isEqualExceptRef) {
+      // Prevent loading an internal resource.
+      return nullptr;
+    }
+  }
+
+  int32_t loadFlags =
+      nsIRequest::LOAD_NORMAL |
+      nsContentUtils::CORSModeToLoadImageFlags(EffectiveCorsMode(uri, aImage));
+
+  const URLExtraData& data = aImage.ExtraData();
+
+  RefPtr<imgRequestProxy> request;
+  nsresult rv = nsContentUtils::LoadImage(
+      uri, &aDocument, &aDocument, data.Principal(), 0, data.ReferrerInfo(),
+      sImageObserver, loadFlags, u"css"_ns, getter_AddRefs(request));
+
+  if (NS_FAILED(rv) || !request) {
+    return nullptr;
+  }
+
+  // This image could be shared across documents, so its load cannot be
+  // canceled, see bug 1800979.
+  request->SetCancelable(false);
+  sImages->GetOrInsertNew(request);
+  return request.forget();
+}
+
+void ImageLoader::UnloadImage(imgRequestProxy* aImage) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aImage);
+
+  if (MOZ_UNLIKELY(!sImages)) {
+    return;  // Shutdown() takes care of it.
+  }
+
+  auto lookup = sImages->Lookup(aImage);
+  MOZ_DIAGNOSTIC_ASSERT(lookup, "Unregistered image?");
+  if (MOZ_UNLIKELY(!lookup)) {
+    return;
+  }
+
+  if (MOZ_UNLIKELY(--lookup.Data()->mSharedCount)) {
+    // Someone else still cares about this image.
+    return;
+  }
+
+  // Now we want to really cancel the request.
+  aImage->SetCancelable(true);
+  aImage->CancelAndForgetObserver(NS_BINDING_ABORTED);
+  MOZ_DIAGNOSTIC_ASSERT(lookup.Data()->mImageLoaders.IsEmpty(),
+                        "Shouldn't be keeping references to any loader "
+                        "by now");
+  lookup.Remove();
+}
+
+void ImageLoader::NoteSharedLoad(imgRequestProxy* aImage) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aImage);
+
+  auto lookup = sImages->Lookup(aImage);
+  MOZ_DIAGNOSTIC_ASSERT(lookup, "Unregistered image?");
+  if (MOZ_UNLIKELY(!lookup)) {
+    return;
+  }
+
+  lookup.Data()->mSharedCount++;
+}
+
+nsPresContext* ImageLoader::GetPresContext() {
+  if (!mDocument) {
+    return nullptr;
+  }
+
+  return mDocument->GetPresContext();
+}
+
+static bool IsRenderNoImages(uint32_t aDisplayItemKey) {
+  DisplayItemType type = GetDisplayItemTypeFromKey(aDisplayItemKey);
+  uint8_t flags = GetDisplayItemFlagsForType(type);
+  return flags & TYPE_RENDERS_NO_IMAGES;
+}
+
+static void InvalidateImages(nsIFrame* aFrame, imgIRequest* aRequest,
+                             bool aForcePaint) {
+  if (!aFrame->StyleVisibility()->IsVisible()) {
+    return;
+  }
+
+  if (aFrame->IsFrameOfType(nsIFrame::eTablePart)) {
+    // Tables don't necessarily build border/background display items
+    // for the individual table part frames, so IterateRetainedDataFor
+    // might not find the right display item.
+    return aFrame->InvalidateFrame();
+  }
+
+  if (aFrame->IsPrimaryFrameOfRootOrBodyElement()) {
+    if (auto* canvas = aFrame->PresShell()->GetCanvasFrame()) {
+      // Try to invalidate the canvas too, in the probable case the background
+      // was propagated to it.
+      InvalidateImages(canvas, aRequest, aForcePaint);
+    }
+  }
+
+  bool invalidateFrame = aForcePaint;
+
+  if (auto userDataTable =
+          aFrame->GetProperty(layers::WebRenderUserDataProperty::Key())) {
+    for (RefPtr<layers::WebRenderUserData> data : userDataTable->Values()) {
+      switch (data->GetType()) {
+        case layers::WebRenderUserData::UserDataType::eFallback:
+          if (!IsRenderNoImages(data->GetDisplayItemKey())) {
+            static_cast<layers::WebRenderFallbackData*>(data.get())
+                ->SetInvalid(true);
+          }
+          // XXX: handle Blob data
+          invalidateFrame = true;
+          break;
+        case layers::WebRenderUserData::UserDataType::eMask:
+          static_cast<layers::WebRenderMaskData*>(data.get())->Invalidate();
+          invalidateFrame = true;
+          break;
+        case layers::WebRenderUserData::UserDataType::eImageProvider:
+          if (static_cast<layers::WebRenderImageProviderData*>(data.get())
+                  ->Invalidate(aRequest->GetProviderId())) {
+            break;
+          }
+          [[fallthrough]];
+        default:
+          invalidateFrame = true;
+          break;
+      }
+    }
+  }
+
+  // Update ancestor rendering observers (-moz-element etc)
+  //
+  // NOTE: We need to do this even if invalidateFrame is false, see bug 1114526.
+  {
+    nsIFrame* f = aFrame;
+    while (f && !f->HasAnyStateBits(NS_FRAME_DESCENDANT_NEEDS_PAINT)) {
+      SVGObserverUtils::InvalidateDirectRenderingObservers(f);
+      f = nsLayoutUtils::GetCrossDocParentFrameInProcess(f);
+    }
+  }
+
+  if (invalidateFrame) {
+    aFrame->SchedulePaint();
+  }
+}
+
+void ImageLoader::UnblockOnloadIfNeeded(FrameWithFlags& aFwf) {
+  if (aFwf.mFlags & Flags::IsBlockingLoadEvent) {
+    mDocument->UnblockOnload(false);
+    aFwf.mFlags &= ~Flags::IsBlockingLoadEvent;
+  }
+}
+
+void ImageLoader::UnblockOnloadIfNeeded(nsIFrame* aFrame,
+                                        imgIRequest* aRequest) {
+  MOZ_ASSERT(aFrame);
+  MOZ_ASSERT(aRequest);
+
+  FrameSet* frameSet = mRequestToFrameMap.Get(aRequest);
+  if (!frameSet) {
+    return;
+  }
+
+  size_t i =
+      frameSet->BinaryIndexOf(FrameWithFlags(aFrame), FrameOnlyComparator());
+  if (i != FrameSet::NoIndex) {
+    UnblockOnloadIfNeeded(frameSet->ElementAt(i));
+  }
+}
+
+// This callback is used to unblock document onload after a reflow
+// triggered from an image load.
+struct ImageLoader::ImageReflowCallback final : public nsIReflowCallback {
+  RefPtr<ImageLoader> mLoader;
+  WeakFrame mFrame;
+  nsCOMPtr<imgIRequest> const mRequest;
+
+  ImageReflowCallback(ImageLoader* aLoader, nsIFrame* aFrame,
+                      imgIRequest* aRequest)
+      : mLoader(aLoader), mFrame(aFrame), mRequest(aRequest) {}
+
+  bool ReflowFinished() override;
+  void ReflowCallbackCanceled() override;
+};
+
+bool ImageLoader::ImageReflowCallback::ReflowFinished() {
+  // Check that the frame is still valid. If it isn't, then onload was
+  // unblocked when the frame was removed from the FrameSet in
+  // RemoveRequestToFrameMapping.
+  if (mFrame.IsAlive()) {
+    mLoader->UnblockOnloadIfNeeded(mFrame, mRequest);
+  }
+
+  // Get rid of this callback object.
+  delete this;
+
+  // We don't need to trigger layout.
+  return false;
+}
+
+void ImageLoader::ImageReflowCallback::ReflowCallbackCanceled() {
+  // Check that the frame is still valid. If it isn't, then onload was
+  // unblocked when the frame was removed from the FrameSet in
+  // RemoveRequestToFrameMapping.
+  if (mFrame.IsAlive()) {
+    mLoader->UnblockOnloadIfNeeded(mFrame, mRequest);
+  }
+
+  // Get rid of this callback object.
+  delete this;
+}
+
+void GlobalImageObserver::Notify(imgIRequest* aRequest, int32_t aType,
+                                 const nsIntRect* aData) {
+  auto entry = sImages->Lookup(aRequest);
+  MOZ_DIAGNOSTIC_ASSERT(entry);
+  if (MOZ_UNLIKELY(!entry)) {
+    return;
+  }
+
+  const auto loadersToNotify =
+      ToTArray<nsTArray<RefPtr<ImageLoader>>>(entry.Data()->mImageLoaders);
+  for (const auto& loader : loadersToNotify) {
+    loader->Notify(aRequest, aType, aData);
+  }
+}
+
+void ImageLoader::Notify(imgIRequest* aRequest, int32_t aType,
+                         const nsIntRect* aData) {
+  nsCString uriString;
+  if (profiler_is_active()) {
+    nsCOMPtr<nsIURI> uri;
+    aRequest->GetFinalURI(getter_AddRefs(uri));
+    if (uri) {
+      uri->GetSpec(uriString);
+    }
+  }
+
+  AUTO_PROFILER_LABEL_DYNAMIC_CSTR("ImageLoader::Notify", OTHER,
+                                   uriString.get());
+
+  if (aType == imgINotificationObserver::SIZE_AVAILABLE) {
+    nsCOMPtr<imgIContainer> image;
+    aRequest->GetImage(getter_AddRefs(image));
+    return OnSizeAvailable(aRequest, image);
+  }
+
+  if (aType == imgINotificationObserver::IS_ANIMATED) {
+    return OnImageIsAnimated(aRequest);
+  }
+
+  if (aType == imgINotificationObserver::FRAME_COMPLETE) {
+    return OnFrameComplete(aRequest);
+  }
+
+  if (aType == imgINotificationObserver::FRAME_UPDATE) {
+    return OnFrameUpdate(aRequest);
+  }
+
+  if (aType == imgINotificationObserver::DECODE_COMPLETE) {
+    nsCOMPtr<imgIContainer> image;
+    aRequest->GetImage(getter_AddRefs(image));
+    if (image && mDocument) {
+      image->PropagateUseCounters(mDocument);
+    }
+  }
+
+  if (aType == imgINotificationObserver::LOAD_COMPLETE) {
+    return OnLoadComplete(aRequest);
+  }
+}
+
+void ImageLoader::OnSizeAvailable(imgIRequest* aRequest,
+                                  imgIContainer* aImage) {
+  nsPresContext* presContext = GetPresContext();
+  if (!presContext) {
+    return;
+  }
+
+  aImage->SetAnimationMode(presContext->ImageAnimationMode());
+
+  FrameSet* frameSet = mRequestToFrameMap.Get(aRequest);
+  if (!frameSet) {
+    return;
+  }
+
+  for (const FrameWithFlags& fwf : *frameSet) {
+    if (fwf.mFlags & Flags::RequiresReflowOnSizeAvailable) {
+      fwf.mFrame->PresShell()->FrameNeedsReflow(
+          fwf.mFrame, IntrinsicDirty::FrameAncestorsAndDescendants,
+          NS_FRAME_IS_DIRTY);
+    }
+  }
+}
+
+void ImageLoader::OnImageIsAnimated(imgIRequest* aRequest) {
+  if (!mDocument) {
+    return;
+  }
+
+  FrameSet* frameSet = mRequestToFrameMap.Get(aRequest);
+  if (!frameSet) {
+    return;
+  }
+
+  // Register with the refresh driver now that we are aware that
+  // we are animated.
+  nsPresContext* presContext = GetPresContext();
+  if (presContext) {
+    nsLayoutUtils::RegisterImageRequest(presContext, aRequest, nullptr);
+  }
+}
+
+void ImageLoader::OnFrameComplete(imgIRequest* aRequest) {
+  ImageFrameChanged(aRequest, /* aFirstFrame = */ true);
+}
+
+void ImageLoader::OnFrameUpdate(imgIRequest* aRequest) {
+  ImageFrameChanged(aRequest, /* aFirstFrame = */ false);
+}
+
+void ImageLoader::ImageFrameChanged(imgIRequest* aRequest, bool aFirstFrame) {
+  if (!mDocument) {
+    return;
+  }
+
+  FrameSet* frameSet = mRequestToFrameMap.Get(aRequest);
+  if (!frameSet) {
+    return;
+  }
+
+  for (FrameWithFlags& fwf : *frameSet) {
+    // Since we just finished decoding a frame, we always want to paint, in
+    // case we're now able to paint an image that we couldn't paint before
+    // (and hence that we don't have retained data for).
+    const bool forceRepaint = aFirstFrame;
+    InvalidateImages(fwf.mFrame, aRequest, forceRepaint);
+    if (!aFirstFrame) {
+      // We don't reflow / try to unblock onload for subsequent frame updates.
+      continue;
+    }
+    if (fwf.mFlags &
+        Flags::RequiresReflowOnFirstFrameCompleteAndLoadEventBlocking) {
+      // Tell the container of the frame to reflow because the image request
+      // has finished decoding its first frame.
+      // FIXME(emilio): Why requesting reflow on the _parent_?
+      nsIFrame* parent = fwf.mFrame->GetInFlowParent();
+      parent->PresShell()->FrameNeedsReflow(
+          parent, IntrinsicDirty::FrameAncestorsAndDescendants,
+          NS_FRAME_IS_DIRTY);
+      // If we need to also potentially unblock onload, do it once reflow is
+      // done, with a reflow callback.
+      if (fwf.mFlags & Flags::IsBlockingLoadEvent) {
+        auto* unblocker = new ImageReflowCallback(this, fwf.mFrame, aRequest);
+        parent->PresShell()->PostReflowCallback(unblocker);
+      }
+    }
+  }
+}
+
+void ImageLoader::OnLoadComplete(imgIRequest* aRequest) {
+  if (!mDocument) {
+    return;
+  }
+
+  uint32_t status = 0;
+  if (NS_FAILED(aRequest->GetImageStatus(&status))) {
+    return;
+  }
+
+  FrameSet* frameSet = mRequestToFrameMap.Get(aRequest);
+  if (!frameSet) {
+    return;
+  }
+
+  for (FrameWithFlags& fwf : *frameSet) {
+    if (status & imgIRequest::STATUS_ERROR) {
+      // Check if aRequest has an error state. If it does, we need to unblock
+      // Document onload for all the frames associated with this request that
+      // have blocked onload. This is what happens in a CORS mode violation, and
+      // may happen during other network events.
+      UnblockOnloadIfNeeded(fwf);
+    }
+    if (fwf.mFrame->StyleVisibility()->IsVisible()) {
+      fwf.mFrame->SchedulePaint();
+    }
+  }
+}
+
+}  // namespace mozilla::css
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