gecko-dev/image/imgLoader.cpp

/* -*- 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/. */

// Undefine windows version of LoadImage because our code uses that name.
#undef LoadImage

#include <algorithm>

#include "ImageLogging.h"
#include "imgLoader.h"

#include "mozilla/Attributes.h"
#include "mozilla/ClearOnShutdown.h"
#include "mozilla/Move.h"
#include "mozilla/NullPrincipal.h"
#include "mozilla/Preferences.h"
#include "mozilla/StaticPrefs_image.h"
#include "mozilla/StaticPrefs_network.h"
#include "mozilla/ChaosMode.h"
#include "mozilla/LoadInfo.h"

#include "nsImageModule.h"
#include "imgRequestProxy.h"

#include "nsCOMPtr.h"

#include "nsContentPolicyUtils.h"
#include "nsContentUtils.h"
#include "nsNetUtil.h"
#include "nsNetCID.h"
#include "nsIProtocolHandler.h"
#include "nsMimeTypes.h"
#include "nsStreamUtils.h"
#include "nsIHttpChannel.h"
#include "nsICacheInfoChannel.h"
#include "nsIClassOfService.h"
#include "nsIInterfaceRequestor.h"
#include "nsIInterfaceRequestorUtils.h"
#include "nsIProgressEventSink.h"
#include "nsIChannelEventSink.h"
#include "nsIAsyncVerifyRedirectCallback.h"
#include "nsIFileURL.h"
#include "nsIFile.h"
#include "nsCRT.h"
#include "nsINetworkPredictor.h"
#include "nsReadableUtils.h"
#include "mozilla/dom/ContentParent.h"
#include "mozilla/dom/nsMixedContentBlocker.h"
#include "mozilla/image/ImageMemoryReporter.h"
#include "mozilla/layers/CompositorManagerChild.h"

#include "nsIApplicationCache.h"
#include "nsIApplicationCacheContainer.h"

#include "nsIMemoryReporter.h"
#include "DecoderFactory.h"
#include "Image.h"
#include "prtime.h"
#include "ReferrerInfo.h"

// we want to explore making the document own the load group
// so we can associate the document URI with the load group.
// until this point, we have an evil hack:
#include "nsIHttpChannelInternal.h"
#include "nsILoadContext.h"
#include "nsILoadGroupChild.h"
#include "nsIDocShell.h"

using namespace mozilla;
using namespace mozilla::dom;
using namespace mozilla::image;
using namespace mozilla::net;

MOZ_DEFINE_MALLOC_SIZE_OF(ImagesMallocSizeOf)

class imgMemoryReporter final : public nsIMemoryReporter {
  ~imgMemoryReporter() = default;

 public:
  NS_DECL_ISUPPORTS

  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
                            nsISupports* aData, bool aAnonymize) override {
    MOZ_ASSERT(NS_IsMainThread());

    layers::CompositorManagerChild* manager =
        CompositorManagerChild::GetInstance();
    if (!manager || !StaticPrefs::image_mem_debug_reporting()) {
      layers::SharedSurfacesMemoryReport sharedSurfaces;
      FinishCollectReports(aHandleReport, aData, aAnonymize, sharedSurfaces);
      return NS_OK;
    }

    RefPtr<imgMemoryReporter> self(this);
    nsCOMPtr<nsIHandleReportCallback> handleReport(aHandleReport);
    nsCOMPtr<nsISupports> data(aData);
    manager->SendReportSharedSurfacesMemory(
        [=](layers::SharedSurfacesMemoryReport aReport) {
          self->FinishCollectReports(handleReport, data, aAnonymize, aReport);
        },
        [=](mozilla::ipc::ResponseRejectReason&& aReason) {
          layers::SharedSurfacesMemoryReport sharedSurfaces;
          self->FinishCollectReports(handleReport, data, aAnonymize,
                                     sharedSurfaces);
        });
    return NS_OK;
  }

  void FinishCollectReports(
      nsIHandleReportCallback* aHandleReport, nsISupports* aData,
      bool aAnonymize, layers::SharedSurfacesMemoryReport& aSharedSurfaces) {
    nsTArray<ImageMemoryCounter> chrome;
    nsTArray<ImageMemoryCounter> content;
    nsTArray<ImageMemoryCounter> uncached;

    for (uint32_t i = 0; i < mKnownLoaders.Length(); i++) {
      for (auto iter = mKnownLoaders[i]->mChromeCache.Iter(); !iter.Done();
           iter.Next()) {
        imgCacheEntry* entry = iter.UserData();
        RefPtr<imgRequest> req = entry->GetRequest();
        RecordCounterForRequest(req, &chrome, !entry->HasNoProxies());
      }
      for (auto iter = mKnownLoaders[i]->mCache.Iter(); !iter.Done();
           iter.Next()) {
        imgCacheEntry* entry = iter.UserData();
        RefPtr<imgRequest> req = entry->GetRequest();
        RecordCounterForRequest(req, &content, !entry->HasNoProxies());
      }
      MutexAutoLock lock(mKnownLoaders[i]->mUncachedImagesMutex);
      for (auto iter = mKnownLoaders[i]->mUncachedImages.Iter(); !iter.Done();
           iter.Next()) {
        nsPtrHashKey<imgRequest>* entry = iter.Get();
        RefPtr<imgRequest> req = entry->GetKey();
        RecordCounterForRequest(req, &uncached, req->HasConsumers());
      }
    }

    // Note that we only need to anonymize content image URIs.

    ReportCounterArray(aHandleReport, aData, chrome, "images/chrome",
                       /* aAnonymize */ false, aSharedSurfaces);

    ReportCounterArray(aHandleReport, aData, content, "images/content",
                       aAnonymize, aSharedSurfaces);

    // Uncached images may be content or chrome, so anonymize them.
    ReportCounterArray(aHandleReport, aData, uncached, "images/uncached",
                       aAnonymize, aSharedSurfaces);

    // Report any shared surfaces that were not merged with the surface cache.
    ImageMemoryReporter::ReportSharedSurfaces(aHandleReport, aData,
                                              aSharedSurfaces);

    nsCOMPtr<nsIMemoryReporterManager> imgr =
        do_GetService("@mozilla.org/memory-reporter-manager;1");
    if (imgr) {
      imgr->EndReport();
    }
  }

  static int64_t ImagesContentUsedUncompressedDistinguishedAmount() {
    size_t n = 0;
    for (uint32_t i = 0; i < imgLoader::sMemReporter->mKnownLoaders.Length();
         i++) {
      for (auto iter = imgLoader::sMemReporter->mKnownLoaders[i]->mCache.Iter();
           !iter.Done(); iter.Next()) {
        imgCacheEntry* entry = iter.UserData();
        if (entry->HasNoProxies()) {
          continue;
        }

        RefPtr<imgRequest> req = entry->GetRequest();
        RefPtr<image::Image> image = req->GetImage();
        if (!image) {
          continue;
        }

        // Both this and EntryImageSizes measure
        // images/content/raster/used/decoded memory.  This function's
        // measurement is secondary -- the result doesn't go in the "explicit"
        // tree -- so we use moz_malloc_size_of instead of ImagesMallocSizeOf to
        // prevent DMD from seeing it reported twice.
        SizeOfState state(moz_malloc_size_of);
        ImageMemoryCounter counter(image, state, /* aIsUsed = */ true);

        n += counter.Values().DecodedHeap();
        n += counter.Values().DecodedNonHeap();
      }
    }
    return n;
  }

  void RegisterLoader(imgLoader* aLoader) {
    mKnownLoaders.AppendElement(aLoader);
  }

  void UnregisterLoader(imgLoader* aLoader) {
    mKnownLoaders.RemoveElement(aLoader);
  }

 private:
  nsTArray<imgLoader*> mKnownLoaders;

  struct MemoryTotal {
    MemoryTotal& operator+=(const ImageMemoryCounter& aImageCounter) {
      if (aImageCounter.Type() == imgIContainer::TYPE_RASTER) {
        if (aImageCounter.IsUsed()) {
          mUsedRasterCounter += aImageCounter.Values();
        } else {
          mUnusedRasterCounter += aImageCounter.Values();
        }
      } else if (aImageCounter.Type() == imgIContainer::TYPE_VECTOR) {
        if (aImageCounter.IsUsed()) {
          mUsedVectorCounter += aImageCounter.Values();
        } else {
          mUnusedVectorCounter += aImageCounter.Values();
        }
      } else {
        MOZ_CRASH("Unexpected image type");
      }

      return *this;
    }

    const MemoryCounter& UsedRaster() const { return mUsedRasterCounter; }
    const MemoryCounter& UnusedRaster() const { return mUnusedRasterCounter; }
    const MemoryCounter& UsedVector() const { return mUsedVectorCounter; }
    const MemoryCounter& UnusedVector() const { return mUnusedVectorCounter; }

   private:
    MemoryCounter mUsedRasterCounter;
    MemoryCounter mUnusedRasterCounter;
    MemoryCounter mUsedVectorCounter;
    MemoryCounter mUnusedVectorCounter;
  };

  // Reports all images of a single kind, e.g. all used chrome images.
  void ReportCounterArray(nsIHandleReportCallback* aHandleReport,
                          nsISupports* aData,
                          nsTArray<ImageMemoryCounter>& aCounterArray,
                          const char* aPathPrefix, bool aAnonymize,
                          layers::SharedSurfacesMemoryReport& aSharedSurfaces) {
    MemoryTotal summaryTotal;
    MemoryTotal nonNotableTotal;

    // Report notable images, and compute total and non-notable aggregate sizes.
    for (uint32_t i = 0; i < aCounterArray.Length(); i++) {
      ImageMemoryCounter& counter = aCounterArray[i];

      if (aAnonymize) {
        counter.URI().Truncate();
        counter.URI().AppendPrintf("<anonymized-%u>", i);
      } else {
        // The URI could be an extremely long data: URI. Truncate if needed.
        static const size_t max = 256;
        if (counter.URI().Length() > max) {
          counter.URI().Truncate(max);
          counter.URI().AppendLiteral(" (truncated)");
        }
        counter.URI().ReplaceChar('/', '\\');
      }

      summaryTotal += counter;

      if (counter.IsNotable() || StaticPrefs::image_mem_debug_reporting()) {
        ReportImage(aHandleReport, aData, aPathPrefix, counter,
                    aSharedSurfaces);
      } else {
        ImageMemoryReporter::TrimSharedSurfaces(counter, aSharedSurfaces);
        nonNotableTotal += counter;
      }
    }

    // Report non-notable images in aggregate.
    ReportTotal(aHandleReport, aData, /* aExplicit = */ true, aPathPrefix,
                "<non-notable images>/", nonNotableTotal);

    // Report a summary in aggregate, outside of the explicit tree.
    ReportTotal(aHandleReport, aData, /* aExplicit = */ false, aPathPrefix, "",
                summaryTotal);
  }

  static void ReportImage(nsIHandleReportCallback* aHandleReport,
                          nsISupports* aData, const char* aPathPrefix,
                          const ImageMemoryCounter& aCounter,
                          layers::SharedSurfacesMemoryReport& aSharedSurfaces) {
    nsAutoCString pathPrefix(NS_LITERAL_CSTRING("explicit/"));
    pathPrefix.Append(aPathPrefix);
    pathPrefix.Append(aCounter.Type() == imgIContainer::TYPE_RASTER
                          ? "/raster/"
                          : "/vector/");
    pathPrefix.Append(aCounter.IsUsed() ? "used/" : "unused/");
    pathPrefix.AppendLiteral("image(");
    pathPrefix.AppendInt(aCounter.IntrinsicSize().width);
    pathPrefix.AppendLiteral("x");
    pathPrefix.AppendInt(aCounter.IntrinsicSize().height);
    pathPrefix.AppendLiteral(", ");

    if (aCounter.URI().IsEmpty()) {
      pathPrefix.AppendLiteral("<unknown URI>");
    } else {
      pathPrefix.Append(aCounter.URI());
    }

    pathPrefix.AppendLiteral(")/");

    ReportSurfaces(aHandleReport, aData, pathPrefix, aCounter, aSharedSurfaces);

    ReportSourceValue(aHandleReport, aData, pathPrefix, aCounter.Values());
  }

  static void ReportSurfaces(
      nsIHandleReportCallback* aHandleReport, nsISupports* aData,
      const nsACString& aPathPrefix, const ImageMemoryCounter& aCounter,
      layers::SharedSurfacesMemoryReport& aSharedSurfaces) {
    for (const SurfaceMemoryCounter& counter : aCounter.Surfaces()) {
      nsAutoCString surfacePathPrefix(aPathPrefix);
      if (counter.IsLocked()) {
        surfacePathPrefix.AppendLiteral("locked/");
      } else {
        surfacePathPrefix.AppendLiteral("unlocked/");
      }
      if (counter.IsFactor2()) {
        surfacePathPrefix.AppendLiteral("factor2/");
      }
      if (counter.CannotSubstitute()) {
        surfacePathPrefix.AppendLiteral("cannot_substitute/");
      }
      surfacePathPrefix.AppendLiteral("surface(");
      surfacePathPrefix.AppendInt(counter.Key().Size().width);
      surfacePathPrefix.AppendLiteral("x");
      surfacePathPrefix.AppendInt(counter.Key().Size().height);

      if (counter.Values().ExternalHandles() > 0) {
        surfacePathPrefix.AppendLiteral(", handles:");
        surfacePathPrefix.AppendInt(
            uint32_t(counter.Values().ExternalHandles()));
      }

      ImageMemoryReporter::AppendSharedSurfacePrefix(surfacePathPrefix, counter,
                                                     aSharedSurfaces);

      if (counter.Type() == SurfaceMemoryCounterType::NORMAL) {
        PlaybackType playback = counter.Key().Playback();
        if (playback == PlaybackType::eAnimated) {
          if (StaticPrefs::image_mem_debug_reporting()) {
            surfacePathPrefix.AppendPrintf(
                " (animation %4u)", uint32_t(counter.Values().FrameIndex()));
          } else {
            surfacePathPrefix.AppendLiteral(" (animation)");
          }
        }

        if (counter.Key().Flags() != DefaultSurfaceFlags()) {
          surfacePathPrefix.AppendLiteral(", flags:");
          surfacePathPrefix.AppendInt(uint32_t(counter.Key().Flags()),
                                      /* aRadix = */ 16);
        }

        if (counter.Key().SVGContext()) {
          const SVGImageContext& context = counter.Key().SVGContext().ref();
          surfacePathPrefix.AppendLiteral(", svgContext:[ ");
          if (context.GetViewportSize()) {
            const CSSIntSize& size = context.GetViewportSize().ref();
            surfacePathPrefix.AppendLiteral("viewport=(");
            surfacePathPrefix.AppendInt(size.width);
            surfacePathPrefix.AppendLiteral("x");
            surfacePathPrefix.AppendInt(size.height);
            surfacePathPrefix.AppendLiteral(") ");
          }
          if (context.GetPreserveAspectRatio()) {
            nsAutoString aspect;
            context.GetPreserveAspectRatio()->ToString(aspect);
            surfacePathPrefix.AppendLiteral("preserveAspectRatio=(");
            LossyAppendUTF16toASCII(aspect, surfacePathPrefix);
            surfacePathPrefix.AppendLiteral(") ");
          }
          if (context.GetContextPaint()) {
            const SVGEmbeddingContextPaint* paint = context.GetContextPaint();
            surfacePathPrefix.AppendLiteral("contextPaint=(");
            if (paint->GetFill()) {
              surfacePathPrefix.AppendLiteral(" fill=");
              surfacePathPrefix.AppendInt(paint->GetFill()->ToABGR(), 16);
            }
            if (paint->GetFillOpacity()) {
              surfacePathPrefix.AppendLiteral(" fillOpa=");
              surfacePathPrefix.AppendFloat(paint->GetFillOpacity());
            }
            if (paint->GetStroke()) {
              surfacePathPrefix.AppendLiteral(" stroke=");
              surfacePathPrefix.AppendInt(paint->GetStroke()->ToABGR(), 16);
            }
            if (paint->GetStrokeOpacity()) {
              surfacePathPrefix.AppendLiteral(" strokeOpa=");
              surfacePathPrefix.AppendFloat(paint->GetStrokeOpacity());
            }
            surfacePathPrefix.AppendLiteral(" ) ");
          }
          surfacePathPrefix.AppendLiteral("]");
        }
      } else if (counter.Type() == SurfaceMemoryCounterType::COMPOSITING) {
        surfacePathPrefix.AppendLiteral(", compositing frame");
      } else if (counter.Type() == SurfaceMemoryCounterType::COMPOSITING_PREV) {
        surfacePathPrefix.AppendLiteral(", compositing prev frame");
      } else {
        MOZ_ASSERT_UNREACHABLE("Unknown counter type");
      }

      surfacePathPrefix.AppendLiteral(")/");

      ReportValues(aHandleReport, aData, surfacePathPrefix, counter.Values());
    }
  }

  static void ReportTotal(nsIHandleReportCallback* aHandleReport,
                          nsISupports* aData, bool aExplicit,
                          const char* aPathPrefix, const char* aPathInfix,
                          const MemoryTotal& aTotal) {
    nsAutoCString pathPrefix;
    if (aExplicit) {
      pathPrefix.AppendLiteral("explicit/");
    }
    pathPrefix.Append(aPathPrefix);

    nsAutoCString rasterUsedPrefix(pathPrefix);
    rasterUsedPrefix.AppendLiteral("/raster/used/");
    rasterUsedPrefix.Append(aPathInfix);
    ReportValues(aHandleReport, aData, rasterUsedPrefix, aTotal.UsedRaster());

    nsAutoCString rasterUnusedPrefix(pathPrefix);
    rasterUnusedPrefix.AppendLiteral("/raster/unused/");
    rasterUnusedPrefix.Append(aPathInfix);
    ReportValues(aHandleReport, aData, rasterUnusedPrefix,
                 aTotal.UnusedRaster());

    nsAutoCString vectorUsedPrefix(pathPrefix);
    vectorUsedPrefix.AppendLiteral("/vector/used/");
    vectorUsedPrefix.Append(aPathInfix);
    ReportValues(aHandleReport, aData, vectorUsedPrefix, aTotal.UsedVector());

    nsAutoCString vectorUnusedPrefix(pathPrefix);
    vectorUnusedPrefix.AppendLiteral("/vector/unused/");
    vectorUnusedPrefix.Append(aPathInfix);
    ReportValues(aHandleReport, aData, vectorUnusedPrefix,
                 aTotal.UnusedVector());
  }

  static void ReportValues(nsIHandleReportCallback* aHandleReport,
                           nsISupports* aData, const nsACString& aPathPrefix,
                           const MemoryCounter& aCounter) {
    ReportSourceValue(aHandleReport, aData, aPathPrefix, aCounter);

    ReportValue(aHandleReport, aData, KIND_HEAP, aPathPrefix, "decoded-heap",
                "Decoded image data which is stored on the heap.",
                aCounter.DecodedHeap());

    ReportValue(aHandleReport, aData, KIND_NONHEAP, aPathPrefix,
                "decoded-nonheap",
                "Decoded image data which isn't stored on the heap.",
                aCounter.DecodedNonHeap());
  }

  static void ReportSourceValue(nsIHandleReportCallback* aHandleReport,
                                nsISupports* aData,
                                const nsACString& aPathPrefix,
                                const MemoryCounter& aCounter) {
    ReportValue(aHandleReport, aData, KIND_HEAP, aPathPrefix, "source",
                "Raster image source data and vector image documents.",
                aCounter.Source());
  }

  static void ReportValue(nsIHandleReportCallback* aHandleReport,
                          nsISupports* aData, int32_t aKind,
                          const nsACString& aPathPrefix,
                          const char* aPathSuffix, const char* aDescription,
                          size_t aValue) {
    if (aValue == 0) {
      return;
    }

    nsAutoCString desc(aDescription);
    nsAutoCString path(aPathPrefix);
    path.Append(aPathSuffix);

    aHandleReport->Callback(EmptyCString(), path, aKind, UNITS_BYTES, aValue,
                            desc, aData);
  }

  static void RecordCounterForRequest(imgRequest* aRequest,
                                      nsTArray<ImageMemoryCounter>* aArray,
                                      bool aIsUsed) {
    RefPtr<image::Image> image = aRequest->GetImage();
    if (!image) {
      return;
    }

    SizeOfState state(ImagesMallocSizeOf);
    ImageMemoryCounter counter(image, state, aIsUsed);

    aArray->AppendElement(std::move(counter));
  }
};

NS_IMPL_ISUPPORTS(imgMemoryReporter, nsIMemoryReporter)

NS_IMPL_ISUPPORTS(nsProgressNotificationProxy, nsIProgressEventSink,
                  nsIChannelEventSink, nsIInterfaceRequestor)

NS_IMETHODIMP
nsProgressNotificationProxy::OnProgress(nsIRequest* request, nsISupports* ctxt,
                                        int64_t progress, int64_t progressMax) {
  nsCOMPtr<nsILoadGroup> loadGroup;
  request->GetLoadGroup(getter_AddRefs(loadGroup));

  nsCOMPtr<nsIProgressEventSink> target;
  NS_QueryNotificationCallbacks(mOriginalCallbacks, loadGroup,
                                NS_GET_IID(nsIProgressEventSink),
                                getter_AddRefs(target));
  if (!target) {
    return NS_OK;
  }
  return target->OnProgress(mImageRequest, ctxt, progress, progressMax);
}

NS_IMETHODIMP
nsProgressNotificationProxy::OnStatus(nsIRequest* request, nsISupports* ctxt,
                                      nsresult status,
                                      const char16_t* statusArg) {
  nsCOMPtr<nsILoadGroup> loadGroup;
  request->GetLoadGroup(getter_AddRefs(loadGroup));

  nsCOMPtr<nsIProgressEventSink> target;
  NS_QueryNotificationCallbacks(mOriginalCallbacks, loadGroup,
                                NS_GET_IID(nsIProgressEventSink),
                                getter_AddRefs(target));
  if (!target) {
    return NS_OK;
  }
  return target->OnStatus(mImageRequest, ctxt, status, statusArg);
}

NS_IMETHODIMP
nsProgressNotificationProxy::AsyncOnChannelRedirect(
    nsIChannel* oldChannel, nsIChannel* newChannel, uint32_t flags,
    nsIAsyncVerifyRedirectCallback* cb) {
  // Tell the original original callbacks about it too
  nsCOMPtr<nsILoadGroup> loadGroup;
  newChannel->GetLoadGroup(getter_AddRefs(loadGroup));
  nsCOMPtr<nsIChannelEventSink> target;
  NS_QueryNotificationCallbacks(mOriginalCallbacks, loadGroup,
                                NS_GET_IID(nsIChannelEventSink),
                                getter_AddRefs(target));
  if (!target) {
    cb->OnRedirectVerifyCallback(NS_OK);
    return NS_OK;
  }

  // Delegate to |target| if set, reusing |cb|
  return target->AsyncOnChannelRedirect(oldChannel, newChannel, flags, cb);
}

NS_IMETHODIMP
nsProgressNotificationProxy::GetInterface(const nsIID& iid, void** result) {
  if (iid.Equals(NS_GET_IID(nsIProgressEventSink))) {
    *result = static_cast<nsIProgressEventSink*>(this);
    NS_ADDREF_THIS();
    return NS_OK;
  }
  if (iid.Equals(NS_GET_IID(nsIChannelEventSink))) {
    *result = static_cast<nsIChannelEventSink*>(this);
    NS_ADDREF_THIS();
    return NS_OK;
  }
  if (mOriginalCallbacks) {
    return mOriginalCallbacks->GetInterface(iid, result);
  }
  return NS_NOINTERFACE;
}

static void NewRequestAndEntry(bool aForcePrincipalCheckForCacheEntry,
                               imgLoader* aLoader, const ImageCacheKey& aKey,
                               imgRequest** aRequest, imgCacheEntry** aEntry) {
  RefPtr<imgRequest> request = new imgRequest(aLoader, aKey);
  RefPtr<imgCacheEntry> entry =
      new imgCacheEntry(aLoader, request, aForcePrincipalCheckForCacheEntry);
  aLoader->AddToUncachedImages(request);
  request.forget(aRequest);
  entry.forget(aEntry);
}

static bool ShouldRevalidateEntry(imgCacheEntry* aEntry, nsLoadFlags aFlags,
                                  bool aHasExpired) {
  bool bValidateEntry = false;

  if (aFlags & nsIRequest::LOAD_BYPASS_CACHE) {
    return false;
  }

  if (aFlags & nsIRequest::VALIDATE_ALWAYS) {
    bValidateEntry = true;
  } else if (aEntry->GetMustValidate()) {
    bValidateEntry = true;
  } else if (aHasExpired) {
    // The cache entry has expired...  Determine whether the stale cache
    // entry can be used without validation...
    if (aFlags &
        (nsIRequest::VALIDATE_NEVER | nsIRequest::VALIDATE_ONCE_PER_SESSION)) {
      // VALIDATE_NEVER and VALIDATE_ONCE_PER_SESSION allow stale cache
      // entries to be used unless they have been explicitly marked to
      // indicate that revalidation is necessary.
      bValidateEntry = false;

    } else if (!(aFlags & nsIRequest::LOAD_FROM_CACHE)) {
      // LOAD_FROM_CACHE allows a stale cache entry to be used... Otherwise,
      // the entry must be revalidated.
      bValidateEntry = true;
    }
  }

  return bValidateEntry;
}

/* Call content policies on cached images that went through a redirect */
static bool ShouldLoadCachedImage(imgRequest* aImgRequest,
                                  nsISupports* aLoadingContext,
                                  nsIPrincipal* aTriggeringPrincipal,
                                  nsContentPolicyType aPolicyType,
                                  bool aSendCSPViolationReports) {
  /* Call content policies on cached images - Bug 1082837
   * Cached images are keyed off of the first uri in a redirect chain.
   * Hence content policies don't get a chance to test the intermediate hops
   * or the final desitnation.  Here we test the final destination using
   * mFinalURI off of the imgRequest and passing it into content policies.
   * For Mixed Content Blocker, we do an additional check to determine if any
   * of the intermediary hops went through an insecure redirect with the
   * mHadInsecureRedirect flag
   */
  bool insecureRedirect = aImgRequest->HadInsecureRedirect();
  nsCOMPtr<nsIURI> contentLocation;
  aImgRequest->GetFinalURI(getter_AddRefs(contentLocation));
  nsresult rv;

  nsCOMPtr<nsINode> requestingNode = do_QueryInterface(aLoadingContext);
  nsCOMPtr<nsIPrincipal> loadingPrincipal =
      requestingNode ? requestingNode->NodePrincipal() : aTriggeringPrincipal;
  // If there is no context and also no triggeringPrincipal, then we use a fresh
  // nullPrincipal as the loadingPrincipal because we can not create a loadinfo
  // without a valid loadingPrincipal.
  if (!loadingPrincipal) {
    loadingPrincipal = NullPrincipal::CreateWithoutOriginAttributes();
  }

  nsCOMPtr<nsILoadInfo> secCheckLoadInfo = new LoadInfo(
      loadingPrincipal, aTriggeringPrincipal, requestingNode,
      nsILoadInfo::SEC_ONLY_FOR_EXPLICIT_CONTENTSEC_CHECK, aPolicyType);

  secCheckLoadInfo->SetSendCSPViolationEvents(aSendCSPViolationReports);

  int16_t decision = nsIContentPolicy::REJECT_REQUEST;
  rv = NS_CheckContentLoadPolicy(contentLocation, secCheckLoadInfo,
                                 EmptyCString(),  // mime guess
                                 &decision, nsContentUtils::GetContentPolicy());
  if (NS_FAILED(rv) || !NS_CP_ACCEPTED(decision)) {
    return false;
  }

  // We call all Content Policies above, but we also have to call mcb
  // individually to check the intermediary redirect hops are secure.
  if (insecureRedirect) {
    // Bug 1314356: If the image ended up in the cache upgraded by HSTS and the
    // page uses upgrade-inscure-requests it had an insecure redirect
    // (http->https). We need to invalidate the image and reload it because
    // mixed content blocker only bails if upgrade-insecure-requests is set on
    // the doc and the resource load is http: which would result in an incorrect
    // mixed content warning.
    nsCOMPtr<nsIDocShell> docShell =
        NS_CP_GetDocShellFromContext(aLoadingContext);
    if (docShell) {
      Document* document = docShell->GetDocument();
      if (document && document->GetUpgradeInsecureRequests(false)) {
        return false;
      }
    }

    if (!nsContentUtils::IsSystemPrincipal(aTriggeringPrincipal)) {
      // Set the requestingLocation from the aTriggeringPrincipal.
      nsCOMPtr<nsIURI> requestingLocation;
      if (aTriggeringPrincipal) {
        rv = aTriggeringPrincipal->GetURI(getter_AddRefs(requestingLocation));
        NS_ENSURE_SUCCESS(rv, false);
      }

      // reset the decision for mixed content blocker check
      decision = nsIContentPolicy::REJECT_REQUEST;
      rv = nsMixedContentBlocker::ShouldLoad(
          insecureRedirect, aPolicyType, contentLocation, requestingLocation,
          aLoadingContext,
          EmptyCString(),  // mime guess
          aTriggeringPrincipal, &decision);
      if (NS_FAILED(rv) || !NS_CP_ACCEPTED(decision)) {
        return false;
      }
    }
  }

  return true;
}

// Returns true if this request is compatible with the given CORS mode on the
// given loading principal, and false if the request may not be reused due
// to CORS.  Also checks the Referrer Policy, since requests with different
// referrers/policies may generate different responses.
static bool ValidateSecurityInfo(imgRequest* request, bool forcePrincipalCheck,
                                 int32_t corsmode,
                                 nsIPrincipal* triggeringPrincipal,
                                 nsISupports* aCX,
                                 nsContentPolicyType aPolicyType,
                                 nsIReferrerInfo* aReferrerInfo) {
  // If the referrer policy doesn't match, we can't use this request.
  // XXX: Note that we only validate referrer policy, not referrerInfo object.
  // We should do with referrerInfo object, but it will cause us to use more
  // resources in the common case (the same policies but different original
  // referrers).
  // XXX: this will return false if an image has different referrer attributes,
  // i.e. we currently don't use the cached image but reload the image with
  // the new referrer policy bug 1174921
  ReferrerPolicy referrerPolicy = ReferrerPolicy::_empty;
  if (aReferrerInfo) {
    referrerPolicy = aReferrerInfo->ReferrerPolicy();
  }

  ReferrerPolicy requestReferrerPolicy = ReferrerPolicy::_empty;
  if (request->GetReferrerInfo()) {
    requestReferrerPolicy = request->GetReferrerInfo()->ReferrerPolicy();
  }

  if (referrerPolicy != requestReferrerPolicy) {
    return false;
  }

  // If the entry's CORS mode doesn't match, or the CORS mode matches but the
  // document principal isn't the same, we can't use this request.
  if (request->GetCORSMode() != corsmode) {
    return false;
  }
  if (request->GetCORSMode() != imgIRequest::CORS_NONE || forcePrincipalCheck) {
    nsCOMPtr<nsIPrincipal> otherprincipal = request->GetTriggeringPrincipal();

    // If we previously had a principal, but we don't now, we can't use this
    // request.
    if (otherprincipal && !triggeringPrincipal) {
      return false;
    }

    if (otherprincipal && triggeringPrincipal) {
      bool equals = false;
      otherprincipal->Equals(triggeringPrincipal, &equals);
      if (!equals) {
        return false;
      }
    }
  }

  // Content Policy Check on Cached Images
  return ShouldLoadCachedImage(request, aCX, triggeringPrincipal, aPolicyType,
                               /* aSendCSPViolationReports */ false);
}

static nsresult NewImageChannel(
    nsIChannel** aResult,
    // If aForcePrincipalCheckForCacheEntry is true, then we will
    // force a principal check even when not using CORS before
    // assuming we have a cache hit on a cache entry that we
    // create for this channel.  This is an out param that should
    // be set to true if this channel ends up depending on
    // aTriggeringPrincipal and false otherwise.
    bool* aForcePrincipalCheckForCacheEntry, nsIURI* aURI,
    nsIURI* aInitialDocumentURI, int32_t aCORSMode,
    nsIReferrerInfo* aReferrerInfo, nsILoadGroup* aLoadGroup,
    const nsCString& aAcceptHeader, nsLoadFlags aLoadFlags,
    nsContentPolicyType aPolicyType, nsIPrincipal* aTriggeringPrincipal,
    nsISupports* aRequestingContext, bool aRespectPrivacy) {
  MOZ_ASSERT(aResult);

  nsresult rv;
  nsCOMPtr<nsIHttpChannel> newHttpChannel;

  nsCOMPtr<nsIInterfaceRequestor> callbacks;

  if (aLoadGroup) {
    // Get the notification callbacks from the load group for the new channel.
    //
    // XXX: This is not exactly correct, because the network request could be
    //      referenced by multiple windows...  However, the new channel needs
    //      something.  So, using the 'first' notification callbacks is better
    //      than nothing...
    //
    aLoadGroup->GetNotificationCallbacks(getter_AddRefs(callbacks));
  }

  // Pass in a nullptr loadgroup because this is the underlying network
  // request. This request may be referenced by several proxy image requests
  // (possibly in different documents).
  // If all of the proxy requests are canceled then this request should be
  // canceled too.
  //

  nsCOMPtr<nsINode> requestingNode = do_QueryInterface(aRequestingContext);

  nsSecurityFlags securityFlags =
      aCORSMode == imgIRequest::CORS_NONE
          ? nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_INHERITS
          : nsILoadInfo::SEC_REQUIRE_CORS_DATA_INHERITS;
  if (aCORSMode == imgIRequest::CORS_ANONYMOUS) {
    securityFlags |= nsILoadInfo::SEC_COOKIES_SAME_ORIGIN;
  } else if (aCORSMode == imgIRequest::CORS_USE_CREDENTIALS) {
    securityFlags |= nsILoadInfo::SEC_COOKIES_INCLUDE;
  }
  securityFlags |= nsILoadInfo::SEC_ALLOW_CHROME;

  // Note we are calling NS_NewChannelWithTriggeringPrincipal() here with a
  // node and a principal. This is for things like background images that are
  // specified by user stylesheets, where the document is being styled, but
  // the principal is that of the user stylesheet.
  if (requestingNode && aTriggeringPrincipal) {
    rv = NS_NewChannelWithTriggeringPrincipal(aResult, aURI, requestingNode,
                                              aTriggeringPrincipal,
                                              securityFlags, aPolicyType,
                                              nullptr,  // PerformanceStorage
                                              nullptr,  // loadGroup
                                              callbacks, aLoadFlags);

    if (NS_FAILED(rv)) {
      return rv;
    }

    if (aPolicyType == nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON) {
      // If this is a favicon loading, we will use the originAttributes from the
      // triggeringPrincipal as the channel's originAttributes. This allows the
      // favicon loading from XUL will use the correct originAttributes.

      nsCOMPtr<nsILoadInfo> loadInfo = (*aResult)->LoadInfo();
      rv = loadInfo->SetOriginAttributes(
          aTriggeringPrincipal->OriginAttributesRef());
    }
  } else {
    // either we are loading something inside a document, in which case
    // we should always have a requestingNode, or we are loading something
    // outside a document, in which case the triggeringPrincipal and
    // triggeringPrincipal should always be the systemPrincipal.
    // However, there are exceptions: one is Notifications which create a
    // channel in the parent process in which case we can't get a
    // requestingNode.
    rv = NS_NewChannel(aResult, aURI, nsContentUtils::GetSystemPrincipal(),
                       securityFlags, aPolicyType,
                       nullptr,  // nsICookieSettings
                       nullptr,  // PerformanceStorage
                       nullptr,  // loadGroup
                       callbacks, aLoadFlags);

    if (NS_FAILED(rv)) {
      return rv;
    }

    // Use the OriginAttributes from the loading principal, if one is available,
    // and adjust the private browsing ID based on what kind of load the caller
    // has asked us to perform.
    OriginAttributes attrs;
    if (aTriggeringPrincipal) {
      attrs = aTriggeringPrincipal->OriginAttributesRef();
    }
    attrs.mPrivateBrowsingId = aRespectPrivacy ? 1 : 0;

    nsCOMPtr<nsILoadInfo> loadInfo = (*aResult)->LoadInfo();
    rv = loadInfo->SetOriginAttributes(attrs);
  }

  if (NS_FAILED(rv)) {
    return rv;
  }

  // only inherit if we have a principal
  *aForcePrincipalCheckForCacheEntry =
      aTriggeringPrincipal && nsContentUtils::ChannelShouldInheritPrincipal(
                                  aTriggeringPrincipal, aURI,
                                  /* aInheritForAboutBlank */ false,
                                  /* aForceInherit */ false);

  // Initialize HTTP-specific attributes
  newHttpChannel = do_QueryInterface(*aResult);
  if (newHttpChannel) {
    rv = newHttpChannel->SetRequestHeader(NS_LITERAL_CSTRING("Accept"),
                                          aAcceptHeader, false);
    MOZ_ASSERT(NS_SUCCEEDED(rv));

    nsCOMPtr<nsIHttpChannelInternal> httpChannelInternal =
        do_QueryInterface(newHttpChannel);
    NS_ENSURE_TRUE(httpChannelInternal, NS_ERROR_UNEXPECTED);
    rv = httpChannelInternal->SetDocumentURI(aInitialDocumentURI);
    MOZ_ASSERT(NS_SUCCEEDED(rv));
    if (aReferrerInfo) {
      DebugOnly<nsresult> rv = newHttpChannel->SetReferrerInfo(aReferrerInfo);
      MOZ_ASSERT(NS_SUCCEEDED(rv));
    }
  }

  // Image channels are loaded by default with reduced priority.
  nsCOMPtr<nsISupportsPriority> p = do_QueryInterface(*aResult);
  if (p) {
    uint32_t priority = nsISupportsPriority::PRIORITY_LOW;

    if (aLoadFlags & nsIRequest::LOAD_BACKGROUND) {
      ++priority;  // further reduce priority for background loads
    }

    p->AdjustPriority(priority);
  }

  // Create a new loadgroup for this new channel, using the old group as
  // the parent. The indirection keeps the channel insulated from cancels,
  // but does allow a way for this revalidation to be associated with at
  // least one base load group for scheduling/caching purposes.

  nsCOMPtr<nsILoadGroup> loadGroup = do_CreateInstance(NS_LOADGROUP_CONTRACTID);
  nsCOMPtr<nsILoadGroupChild> childLoadGroup = do_QueryInterface(loadGroup);
  if (childLoadGroup) {
    childLoadGroup->SetParentLoadGroup(aLoadGroup);
  }
  (*aResult)->SetLoadGroup(loadGroup);

  return NS_OK;
}

/* static */
uint32_t imgCacheEntry::SecondsFromPRTime(PRTime prTime) {
  return uint32_t(int64_t(prTime) / int64_t(PR_USEC_PER_SEC));
}

imgCacheEntry::imgCacheEntry(imgLoader* loader, imgRequest* request,
                             bool forcePrincipalCheck)
    : mLoader(loader),
      mRequest(request),
      mDataSize(0),
      mTouchedTime(SecondsFromPRTime(PR_Now())),
      mLoadTime(SecondsFromPRTime(PR_Now())),
      mExpiryTime(0),
      mMustValidate(false),
      // We start off as evicted so we don't try to update the cache.
      // PutIntoCache will set this to false.
      mEvicted(true),
      mHasNoProxies(true),
      mForcePrincipalCheck(forcePrincipalCheck) {}

imgCacheEntry::~imgCacheEntry() {
  LOG_FUNC(gImgLog, "imgCacheEntry::~imgCacheEntry()");
}

void imgCacheEntry::Touch(bool updateTime /* = true */) {
  LOG_SCOPE(gImgLog, "imgCacheEntry::Touch");

  if (updateTime) {
    mTouchedTime = SecondsFromPRTime(PR_Now());
  }

  UpdateCache();
}

void imgCacheEntry::UpdateCache(int32_t diff /* = 0 */) {
  // Don't update the cache if we've been removed from it or it doesn't care
  // about our size or usage.
  if (!Evicted() && HasNoProxies()) {
    mLoader->CacheEntriesChanged(mRequest->IsChrome(), diff);
  }
}

void imgCacheEntry::UpdateLoadTime() {
  mLoadTime = SecondsFromPRTime(PR_Now());
}

void imgCacheEntry::SetHasNoProxies(bool hasNoProxies) {
  if (MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
    if (hasNoProxies) {
      LOG_FUNC_WITH_PARAM(gImgLog, "imgCacheEntry::SetHasNoProxies true", "uri",
                          mRequest->CacheKey().URI());
    } else {
      LOG_FUNC_WITH_PARAM(gImgLog, "imgCacheEntry::SetHasNoProxies false",
                          "uri", mRequest->CacheKey().URI());
    }
  }

  mHasNoProxies = hasNoProxies;
}

imgCacheQueue::imgCacheQueue() : mDirty(false), mSize(0) {}

void imgCacheQueue::UpdateSize(int32_t diff) { mSize += diff; }

uint32_t imgCacheQueue::GetSize() const { return mSize; }

void imgCacheQueue::Remove(imgCacheEntry* entry) {
  uint64_t index = mQueue.IndexOf(entry);
  if (index == queueContainer::NoIndex) {
    return;
  }

  mSize -= mQueue[index]->GetDataSize();

  // If the queue is clean and this is the first entry,
  // then we can efficiently remove the entry without
  // dirtying the sort order.
  if (!IsDirty() && index == 0) {
    std::pop_heap(mQueue.begin(), mQueue.end(), imgLoader::CompareCacheEntries);
    mQueue.RemoveLastElement();
    return;
  }

  // Remove from the middle of the list.  This potentially
  // breaks the binary heap sort order.
  mQueue.RemoveElementAt(index);

  // If we only have one entry or the queue is empty, though,
  // then the sort order is still effectively good.  Simply
  // refresh the list to clear the dirty flag.
  if (mQueue.Length() <= 1) {
    Refresh();
    return;
  }

  // Otherwise we must mark the queue dirty and potentially
  // trigger an expensive sort later.
  MarkDirty();
}

void imgCacheQueue::Push(imgCacheEntry* entry) {
  mSize += entry->GetDataSize();

  RefPtr<imgCacheEntry> refptr(entry);
  mQueue.AppendElement(std::move(refptr));
  // If we're not dirty already, then we can efficiently add this to the
  // binary heap immediately.  This is only O(log n).
  if (!IsDirty()) {
    std::push_heap(mQueue.begin(), mQueue.end(),
                   imgLoader::CompareCacheEntries);
  }
}

already_AddRefed<imgCacheEntry> imgCacheQueue::Pop() {
  if (mQueue.IsEmpty()) {
    return nullptr;
  }
  if (IsDirty()) {
    Refresh();
  }

  std::pop_heap(mQueue.begin(), mQueue.end(), imgLoader::CompareCacheEntries);
  RefPtr<imgCacheEntry> entry = mQueue.PopLastElement();

  mSize -= entry->GetDataSize();
  return entry.forget();
}

void imgCacheQueue::Refresh() {
  // Resort the list.  This is an O(3 * n) operation and best avoided
  // if possible.
  std::make_heap(mQueue.begin(), mQueue.end(), imgLoader::CompareCacheEntries);
  mDirty = false;
}

void imgCacheQueue::MarkDirty() { mDirty = true; }

bool imgCacheQueue::IsDirty() { return mDirty; }

uint32_t imgCacheQueue::GetNumElements() const { return mQueue.Length(); }

bool imgCacheQueue::Contains(imgCacheEntry* aEntry) const {
  return mQueue.Contains(aEntry);
}

imgCacheQueue::iterator imgCacheQueue::begin() { return mQueue.begin(); }

imgCacheQueue::const_iterator imgCacheQueue::begin() const {
  return mQueue.begin();
}

imgCacheQueue::iterator imgCacheQueue::end() { return mQueue.end(); }

imgCacheQueue::const_iterator imgCacheQueue::end() const {
  return mQueue.end();
}

nsresult imgLoader::CreateNewProxyForRequest(
    imgRequest* aRequest, nsILoadGroup* aLoadGroup, Document* aLoadingDocument,
    imgINotificationObserver* aObserver, nsLoadFlags aLoadFlags,
    imgRequestProxy** _retval) {
  LOG_SCOPE_WITH_PARAM(gImgLog, "imgLoader::CreateNewProxyForRequest",
                       "imgRequest", aRequest);

  /* XXX If we move decoding onto separate threads, we should save off the
     calling thread here and pass it off to |proxyRequest| so that it call
     proxy calls to |aObserver|.
   */

  RefPtr<imgRequestProxy> proxyRequest = new imgRequestProxy();

  /* It is important to call |SetLoadFlags()| before calling |Init()| because
     |Init()| adds the request to the loadgroup.
   */
  proxyRequest->SetLoadFlags(aLoadFlags);

  nsCOMPtr<nsIURI> uri;
  aRequest->GetURI(getter_AddRefs(uri));

  // init adds itself to imgRequest's list of observers
  nsresult rv = proxyRequest->Init(aRequest, aLoadGroup, aLoadingDocument, uri,
                                   aObserver);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  proxyRequest.forget(_retval);
  return NS_OK;
}

class imgCacheExpirationTracker final
    : public nsExpirationTracker<imgCacheEntry, 3> {
  enum { TIMEOUT_SECONDS = 10 };

 public:
  imgCacheExpirationTracker();

 protected:
  void NotifyExpired(imgCacheEntry* entry) override;
};

imgCacheExpirationTracker::imgCacheExpirationTracker()
    : nsExpirationTracker<imgCacheEntry, 3>(
          TIMEOUT_SECONDS * 1000, "imgCacheExpirationTracker",
          SystemGroup::EventTargetFor(TaskCategory::Other)) {}

void imgCacheExpirationTracker::NotifyExpired(imgCacheEntry* entry) {
  // Hold on to a reference to this entry, because the expiration tracker
  // mechanism doesn't.
  RefPtr<imgCacheEntry> kungFuDeathGrip(entry);

  if (MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
    RefPtr<imgRequest> req = entry->GetRequest();
    if (req) {
      LOG_FUNC_WITH_PARAM(gImgLog, "imgCacheExpirationTracker::NotifyExpired",
                          "entry", req->CacheKey().URI());
    }
  }

  // We can be called multiple times on the same entry. Don't do work multiple
  // times.
  if (!entry->Evicted()) {
    entry->Loader()->RemoveFromCache(entry);
  }

  entry->Loader()->VerifyCacheSizes();
}

///////////////////////////////////////////////////////////////////////////////
// imgLoader
///////////////////////////////////////////////////////////////////////////////

double imgLoader::sCacheTimeWeight;
uint32_t imgLoader::sCacheMaxSize;
imgMemoryReporter* imgLoader::sMemReporter;

NS_IMPL_ISUPPORTS(imgLoader, imgILoader, nsIContentSniffer, imgICache,
                  nsISupportsWeakReference, nsIObserver)

static imgLoader* gNormalLoader = nullptr;
static imgLoader* gPrivateBrowsingLoader = nullptr;

/* static */
already_AddRefed<imgLoader> imgLoader::CreateImageLoader() {
  // In some cases, such as xpctests, XPCOM modules are not automatically
  // initialized.  We need to make sure that our module is initialized before
  // we hand out imgLoader instances and code starts using them.
  mozilla::image::EnsureModuleInitialized();

  RefPtr<imgLoader> loader = new imgLoader();
  loader->Init();

  return loader.forget();
}

imgLoader* imgLoader::NormalLoader() {
  if (!gNormalLoader) {
    gNormalLoader = CreateImageLoader().take();
  }
  return gNormalLoader;
}

imgLoader* imgLoader::PrivateBrowsingLoader() {
  if (!gPrivateBrowsingLoader) {
    gPrivateBrowsingLoader = CreateImageLoader().take();
    gPrivateBrowsingLoader->RespectPrivacyNotifications();
  }
  return gPrivateBrowsingLoader;
}

imgLoader::imgLoader()
    : mUncachedImagesMutex("imgLoader::UncachedImages"),
      mRespectPrivacy(false) {
  sMemReporter->AddRef();
  sMemReporter->RegisterLoader(this);
}

imgLoader::~imgLoader() {
  ClearChromeImageCache();
  ClearImageCache();
  {
    // If there are any of our imgRequest's left they are in the uncached
    // images set, so clear their pointer to us.
    MutexAutoLock lock(mUncachedImagesMutex);
    for (auto iter = mUncachedImages.Iter(); !iter.Done(); iter.Next()) {
      nsPtrHashKey<imgRequest>* entry = iter.Get();
      RefPtr<imgRequest> req = entry->GetKey();
      req->ClearLoader();
    }
  }
  sMemReporter->UnregisterLoader(this);
  sMemReporter->Release();
}

void imgLoader::VerifyCacheSizes() {
#ifdef DEBUG
  if (!mCacheTracker) {
    return;
  }

  uint32_t cachesize = mCache.Count() + mChromeCache.Count();
  uint32_t queuesize =
      mCacheQueue.GetNumElements() + mChromeCacheQueue.GetNumElements();
  uint32_t trackersize = 0;
  for (nsExpirationTracker<imgCacheEntry, 3>::Iterator it(mCacheTracker.get());
       it.Next();) {
    trackersize++;
  }
  MOZ_ASSERT(queuesize == trackersize, "Queue and tracker sizes out of sync!");
  MOZ_ASSERT(queuesize <= cachesize, "Queue has more elements than cache!");
#endif
}

imgLoader::imgCacheTable& imgLoader::GetCache(bool aForChrome) {
  return aForChrome ? mChromeCache : mCache;
}

imgLoader::imgCacheTable& imgLoader::GetCache(const ImageCacheKey& aKey) {
  return GetCache(aKey.IsChrome());
}

imgCacheQueue& imgLoader::GetCacheQueue(bool aForChrome) {
  return aForChrome ? mChromeCacheQueue : mCacheQueue;
}

imgCacheQueue& imgLoader::GetCacheQueue(const ImageCacheKey& aKey) {
  return GetCacheQueue(aKey.IsChrome());
}

void imgLoader::GlobalInit() {
  sCacheTimeWeight = StaticPrefs::image_cache_timeweight_AtStartup() / 1000.0;
  int32_t cachesize = StaticPrefs::image_cache_size_AtStartup();
  sCacheMaxSize = cachesize > 0 ? cachesize : 0;

  sMemReporter = new imgMemoryReporter();
  RegisterStrongAsyncMemoryReporter(sMemReporter);
  RegisterImagesContentUsedUncompressedDistinguishedAmount(
      imgMemoryReporter::ImagesContentUsedUncompressedDistinguishedAmount);
}

void imgLoader::ShutdownMemoryReporter() {
  UnregisterImagesContentUsedUncompressedDistinguishedAmount();
  UnregisterStrongMemoryReporter(sMemReporter);
}

nsresult imgLoader::InitCache() {
  nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
  if (!os) {
    return NS_ERROR_FAILURE;
  }

  os->AddObserver(this, "memory-pressure", false);
  os->AddObserver(this, "chrome-flush-caches", false);
  os->AddObserver(this, "last-pb-context-exited", false);
  os->AddObserver(this, "profile-before-change", false);
  os->AddObserver(this, "xpcom-shutdown", false);

  mCacheTracker = MakeUnique<imgCacheExpirationTracker>();

  return NS_OK;
}

nsresult imgLoader::Init() {
  InitCache();

  ReadAcceptHeaderPref();

  Preferences::AddWeakObserver(this, "image.http.accept");

  return NS_OK;
}

NS_IMETHODIMP
imgLoader::RespectPrivacyNotifications() {
  mRespectPrivacy = true;
  return NS_OK;
}

NS_IMETHODIMP
imgLoader::Observe(nsISupports* aSubject, const char* aTopic,
                   const char16_t* aData) {
  // We listen for pref change notifications...
  if (!strcmp(aTopic, NS_PREFBRANCH_PREFCHANGE_TOPIC_ID)) {
    if (!NS_strcmp(aData, u"image.http.accept")) {
      ReadAcceptHeaderPref();
    }

  } else if (strcmp(aTopic, "memory-pressure") == 0) {
    MinimizeCaches();
  } else if (strcmp(aTopic, "chrome-flush-caches") == 0) {
    MinimizeCaches();
    ClearChromeImageCache();
  } else if (strcmp(aTopic, "last-pb-context-exited") == 0) {
    if (mRespectPrivacy) {
      ClearImageCache();
      ClearChromeImageCache();
    }
  } else if (strcmp(aTopic, "profile-before-change") == 0) {
    mCacheTracker = nullptr;
  } else if (strcmp(aTopic, "xpcom-shutdown") == 0) {
    mCacheTracker = nullptr;
    ShutdownMemoryReporter();

  } else {
    // (Nothing else should bring us here)
    MOZ_ASSERT(0, "Invalid topic received");
  }

  return NS_OK;
}

void imgLoader::ReadAcceptHeaderPref() {
  nsAutoCString accept;
  nsresult rv = Preferences::GetCString("image.http.accept", accept);
  if (NS_SUCCEEDED(rv)) {
    mAcceptHeader = accept;
  } else {
    mAcceptHeader =
        IMAGE_PNG "," IMAGE_WILDCARD ";q=0.8," ANY_WILDCARD ";q=0.5";
  }
}

NS_IMETHODIMP
imgLoader::ClearCache(bool chrome) {
  if (XRE_IsParentProcess()) {
    bool privateLoader = this == gPrivateBrowsingLoader;
    for (auto* cp : ContentParent::AllProcesses(ContentParent::eLive)) {
      Unused << cp->SendClearImageCache(privateLoader, chrome);
    }
  }

  if (chrome) {
    return ClearChromeImageCache();
  }
  return ClearImageCache();
}

NS_IMETHODIMP
imgLoader::RemoveEntriesFromPrincipal(nsIPrincipal* aPrincipal) {
  nsAutoString origin;
  nsresult rv = nsContentUtils::GetUTFOrigin(aPrincipal, origin);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  AutoTArray<RefPtr<imgCacheEntry>, 128> entriesToBeRemoved;

  imgCacheTable& cache =
      GetCache(nsContentUtils::IsSystemPrincipal(aPrincipal));
  for (auto iter = cache.Iter(); !iter.Done(); iter.Next()) {
    auto& key = iter.Key();

    if (key.OriginAttributesRef() !=
        BasePrincipal::Cast(aPrincipal)->OriginAttributesRef()) {
      continue;
    }

    nsAutoString imageOrigin;
    nsresult rv = nsContentUtils::GetUTFOrigin(key.URI(), imageOrigin);
    if (NS_WARN_IF(NS_FAILED(rv))) {
      continue;
    }

    if (imageOrigin == origin) {
      entriesToBeRemoved.AppendElement(iter.Data());
    }
  }

  for (auto& entry : entriesToBeRemoved) {
    if (!RemoveFromCache(entry)) {
      NS_WARNING(
          "Couldn't remove an entry from the cache in "
          "RemoveEntriesFromPrincipal()\n");
    }
  }

  return NS_OK;
}

NS_IMETHODIMP
imgLoader::RemoveEntry(nsIURI* aURI, Document* aDoc) {
  if (aURI) {
    OriginAttributes attrs;
    if (aDoc) {
      nsCOMPtr<nsIPrincipal> principal = aDoc->NodePrincipal();
      if (principal) {
        attrs = principal->OriginAttributesRef();
      }
    }

    ImageCacheKey key(aURI, attrs, aDoc);
    if (RemoveFromCache(key)) {
      return NS_OK;
    }
  }
  return NS_ERROR_NOT_AVAILABLE;
}

NS_IMETHODIMP
imgLoader::FindEntryProperties(nsIURI* uri, Document* aDoc,
                               nsIProperties** _retval) {
  *_retval = nullptr;

  OriginAttributes attrs;
  if (aDoc) {
    nsCOMPtr<nsIPrincipal> principal = aDoc->NodePrincipal();
    if (principal) {
      attrs = principal->OriginAttributesRef();
    }
  }

  ImageCacheKey key(uri, attrs, aDoc);
  imgCacheTable& cache = GetCache(key);

  RefPtr<imgCacheEntry> entry;
  if (cache.Get(key, getter_AddRefs(entry)) && entry) {
    if (mCacheTracker && entry->HasNoProxies()) {
      mCacheTracker->MarkUsed(entry);
    }

    RefPtr<imgRequest> request = entry->GetRequest();
    if (request) {
      nsCOMPtr<nsIProperties> properties = request->Properties();
      properties.forget(_retval);
    }
  }

  return NS_OK;
}

NS_IMETHODIMP_(void)
imgLoader::ClearCacheForControlledDocument(Document* aDoc) {
  MOZ_ASSERT(aDoc);
  AutoTArray<RefPtr<imgCacheEntry>, 128> entriesToBeRemoved;
  imgCacheTable& cache = GetCache(false);
  for (auto iter = cache.Iter(); !iter.Done(); iter.Next()) {
    auto& key = iter.Key();
    if (key.ControlledDocument() == aDoc) {
      entriesToBeRemoved.AppendElement(iter.Data());
    }
  }
  for (auto& entry : entriesToBeRemoved) {
    if (!RemoveFromCache(entry)) {
      NS_WARNING(
          "Couldn't remove an entry from the cache in "
          "ClearCacheForControlledDocument()\n");
    }
  }
}

void imgLoader::Shutdown() {
  NS_IF_RELEASE(gNormalLoader);
  gNormalLoader = nullptr;
  NS_IF_RELEASE(gPrivateBrowsingLoader);
  gPrivateBrowsingLoader = nullptr;
}

nsresult imgLoader::ClearChromeImageCache() {
  return EvictEntries(mChromeCache);
}

nsresult imgLoader::ClearImageCache() { return EvictEntries(mCache); }

void imgLoader::MinimizeCaches() {
  EvictEntries(mCacheQueue);
  EvictEntries(mChromeCacheQueue);
}

bool imgLoader::PutIntoCache(const ImageCacheKey& aKey, imgCacheEntry* entry) {
  imgCacheTable& cache = GetCache(aKey);

  LOG_STATIC_FUNC_WITH_PARAM(gImgLog, "imgLoader::PutIntoCache", "uri",
                             aKey.URI());

  // Check to see if this request already exists in the cache. If so, we'll
  // replace the old version.
  RefPtr<imgCacheEntry> tmpCacheEntry;
  if (cache.Get(aKey, getter_AddRefs(tmpCacheEntry)) && tmpCacheEntry) {
    MOZ_LOG(
        gImgLog, LogLevel::Debug,
        ("[this=%p] imgLoader::PutIntoCache -- Element already in the cache",
         nullptr));
    RefPtr<imgRequest> tmpRequest = tmpCacheEntry->GetRequest();

    // If it already exists, and we're putting the same key into the cache, we
    // should remove the old version.
    MOZ_LOG(gImgLog, LogLevel::Debug,
            ("[this=%p] imgLoader::PutIntoCache -- Replacing cached element",
             nullptr));

    RemoveFromCache(aKey);
  } else {
    MOZ_LOG(gImgLog, LogLevel::Debug,
            ("[this=%p] imgLoader::PutIntoCache --"
             " Element NOT already in the cache",
             nullptr));
  }

  cache.Put(aKey, entry);

  // We can be called to resurrect an evicted entry.
  if (entry->Evicted()) {
    entry->SetEvicted(false);
  }

  // If we're resurrecting an entry with no proxies, put it back in the
  // tracker and queue.
  if (entry->HasNoProxies()) {
    nsresult addrv = NS_OK;

    if (mCacheTracker) {
      addrv = mCacheTracker->AddObject(entry);
    }

    if (NS_SUCCEEDED(addrv)) {
      imgCacheQueue& queue = GetCacheQueue(aKey);
      queue.Push(entry);
    }
  }

  RefPtr<imgRequest> request = entry->GetRequest();
  request->SetIsInCache(true);
  RemoveFromUncachedImages(request);

  return true;
}

bool imgLoader::SetHasNoProxies(imgRequest* aRequest, imgCacheEntry* aEntry) {
  LOG_STATIC_FUNC_WITH_PARAM(gImgLog, "imgLoader::SetHasNoProxies", "uri",
                             aRequest->CacheKey().URI());

  aEntry->SetHasNoProxies(true);

  if (aEntry->Evicted()) {
    return false;
  }

  imgCacheQueue& queue = GetCacheQueue(aRequest->IsChrome());

  nsresult addrv = NS_OK;

  if (mCacheTracker) {
    addrv = mCacheTracker->AddObject(aEntry);
  }

  if (NS_SUCCEEDED(addrv)) {
    queue.Push(aEntry);
  }

  imgCacheTable& cache = GetCache(aRequest->IsChrome());
  CheckCacheLimits(cache, queue);

  return true;
}

bool imgLoader::SetHasProxies(imgRequest* aRequest) {
  VerifyCacheSizes();

  const ImageCacheKey& key = aRequest->CacheKey();
  imgCacheTable& cache = GetCache(key);

  LOG_STATIC_FUNC_WITH_PARAM(gImgLog, "imgLoader::SetHasProxies", "uri",
                             key.URI());

  RefPtr<imgCacheEntry> entry;
  if (cache.Get(key, getter_AddRefs(entry)) && entry) {
    // Make sure the cache entry is for the right request
    RefPtr<imgRequest> entryRequest = entry->GetRequest();
    if (entryRequest == aRequest && entry->HasNoProxies()) {
      imgCacheQueue& queue = GetCacheQueue(key);
      queue.Remove(entry);

      if (mCacheTracker) {
        mCacheTracker->RemoveObject(entry);
      }

      entry->SetHasNoProxies(false);

      return true;
    }
  }

  return false;
}

void imgLoader::CacheEntriesChanged(bool aForChrome,
                                    int32_t aSizeDiff /* = 0 */) {
  imgCacheQueue& queue = GetCacheQueue(aForChrome);
  // We only need to dirty the queue if there is any sorting
  // taking place.  Empty or single-entry lists can't become
  // dirty.
  if (queue.GetNumElements() > 1) {
    queue.MarkDirty();
  }
  queue.UpdateSize(aSizeDiff);
}

void imgLoader::CheckCacheLimits(imgCacheTable& cache, imgCacheQueue& queue) {
  if (queue.GetNumElements() == 0) {
    NS_ASSERTION(queue.GetSize() == 0,
                 "imgLoader::CheckCacheLimits -- incorrect cache size");
  }

  // Remove entries from the cache until we're back at our desired max size.
  while (queue.GetSize() > sCacheMaxSize) {
    // Remove the first entry in the queue.
    RefPtr<imgCacheEntry> entry(queue.Pop());

    NS_ASSERTION(entry, "imgLoader::CheckCacheLimits -- NULL entry pointer");

    if (MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
      RefPtr<imgRequest> req = entry->GetRequest();
      if (req) {
        LOG_STATIC_FUNC_WITH_PARAM(gImgLog, "imgLoader::CheckCacheLimits",
                                   "entry", req->CacheKey().URI());
      }
    }

    if (entry) {
      // We just popped this entry from the queue, so pass AlreadyRemoved
      // to avoid searching the queue again in RemoveFromCache.
      RemoveFromCache(entry, QueueState::AlreadyRemoved);
    }
  }
}

bool imgLoader::ValidateRequestWithNewChannel(
    imgRequest* request, nsIURI* aURI, nsIURI* aInitialDocumentURI,
    nsIReferrerInfo* aReferrerInfo, nsILoadGroup* aLoadGroup,
    imgINotificationObserver* aObserver, nsISupports* aCX,
    Document* aLoadingDocument, uint64_t aInnerWindowId, nsLoadFlags aLoadFlags,
    nsContentPolicyType aLoadPolicyType, imgRequestProxy** aProxyRequest,
    nsIPrincipal* aTriggeringPrincipal, int32_t aCORSMode,
    bool* aNewChannelCreated) {
  // now we need to insert a new channel request object in between the real
  // request and the proxy that basically delays loading the image until it
  // gets a 304 or figures out that this needs to be a new request

  nsresult rv;

  // If we're currently in the middle of validating this request, just hand
  // back a proxy to it; the required work will be done for us.
  if (request->GetValidator()) {
    rv = CreateNewProxyForRequest(request, aLoadGroup, aLoadingDocument,
                                  aObserver, aLoadFlags, aProxyRequest);
    if (NS_FAILED(rv)) {
      return false;
    }

    if (*aProxyRequest) {
      imgRequestProxy* proxy = static_cast<imgRequestProxy*>(*aProxyRequest);

      // We will send notifications from imgCacheValidator::OnStartRequest().
      // In the mean time, we must defer notifications because we are added to
      // the imgRequest's proxy list, and we can get extra notifications
      // resulting from methods such as StartDecoding(). See bug 579122.
      proxy->MarkValidating();

      // Attach the proxy without notifying
      request->GetValidator()->AddProxy(proxy);
    }

    return NS_SUCCEEDED(rv);
  }
  // We will rely on Necko to cache this request when it's possible, and to
  // tell imgCacheValidator::OnStartRequest whether the request came from its
  // cache.
  nsCOMPtr<nsIChannel> newChannel;
  bool forcePrincipalCheck;
  rv = NewImageChannel(getter_AddRefs(newChannel), &forcePrincipalCheck, aURI,
                       aInitialDocumentURI, aCORSMode, aReferrerInfo,
                       aLoadGroup, mAcceptHeader, aLoadFlags, aLoadPolicyType,
                       aTriggeringPrincipal, aCX, mRespectPrivacy);
  if (NS_FAILED(rv)) {
    return false;
  }

  if (aNewChannelCreated) {
    *aNewChannelCreated = true;
  }

  RefPtr<imgRequestProxy> req;
  rv = CreateNewProxyForRequest(request, aLoadGroup, aLoadingDocument,
                                aObserver, aLoadFlags, getter_AddRefs(req));
  if (NS_FAILED(rv)) {
    return false;
  }

  // Make sure that OnStatus/OnProgress calls have the right request set...
  RefPtr<nsProgressNotificationProxy> progressproxy =
      new nsProgressNotificationProxy(newChannel, req);
  if (!progressproxy) {
    return false;
  }

  RefPtr<imgCacheValidator> hvc = new imgCacheValidator(
      progressproxy, this, request, aCX, aInnerWindowId, forcePrincipalCheck);

  // Casting needed here to get past multiple inheritance.
  nsCOMPtr<nsIStreamListener> listener =
      do_QueryInterface(static_cast<nsIThreadRetargetableStreamListener*>(hvc));
  NS_ENSURE_TRUE(listener, false);

  // We must set the notification callbacks before setting up the
  // CORS listener, because that's also interested inthe
  // notification callbacks.
  newChannel->SetNotificationCallbacks(hvc);

  request->SetValidator(hvc);

  // We will send notifications from imgCacheValidator::OnStartRequest().
  // In the mean time, we must defer notifications because we are added to
  // the imgRequest's proxy list, and we can get extra notifications
  // resulting from methods such as StartDecoding(). See bug 579122.
  req->MarkValidating();

  // Add the proxy without notifying
  hvc->AddProxy(req);

  mozilla::net::PredictorLearn(aURI, aInitialDocumentURI,
                               nsINetworkPredictor::LEARN_LOAD_SUBRESOURCE,
                               aLoadGroup);
  rv = newChannel->AsyncOpen(listener);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    req->CancelAndForgetObserver(rv);
    return false;
  }

  req.forget(aProxyRequest);
  return true;
}

bool imgLoader::ValidateEntry(
    imgCacheEntry* aEntry, nsIURI* aURI, nsIURI* aInitialDocumentURI,
    nsIReferrerInfo* aReferrerInfo, nsILoadGroup* aLoadGroup,
    imgINotificationObserver* aObserver, nsISupports* aCX,
    Document* aLoadingDocument, nsLoadFlags aLoadFlags,
    nsContentPolicyType aLoadPolicyType, bool aCanMakeNewChannel,
    bool* aNewChannelCreated, imgRequestProxy** aProxyRequest,
    nsIPrincipal* aTriggeringPrincipal, int32_t aCORSMode) {
  LOG_SCOPE(gImgLog, "imgLoader::ValidateEntry");

  // If the expiration time is zero, then the request has not gotten far enough
  // to know when it will expire.
  uint32_t expiryTime = aEntry->GetExpiryTime();
  bool hasExpired = expiryTime != 0 &&
                    expiryTime <= imgCacheEntry::SecondsFromPRTime(PR_Now());

  nsresult rv;

  // Special treatment for file URLs - aEntry has expired if file has changed
  nsCOMPtr<nsIFileURL> fileUrl(do_QueryInterface(aURI));
  if (fileUrl) {
    uint32_t lastModTime = aEntry->GetLoadTime();

    nsCOMPtr<nsIFile> theFile;
    rv = fileUrl->GetFile(getter_AddRefs(theFile));
    if (NS_SUCCEEDED(rv)) {
      PRTime fileLastMod;
      rv = theFile->GetLastModifiedTime(&fileLastMod);
      if (NS_SUCCEEDED(rv)) {
        // nsIFile uses millisec, NSPR usec
        fileLastMod *= 1000;
        hasExpired =
            imgCacheEntry::SecondsFromPRTime((PRTime)fileLastMod) > lastModTime;
      }
    }
  }

  RefPtr<imgRequest> request(aEntry->GetRequest());

  if (!request) {
    return false;
  }

  if (!ValidateSecurityInfo(request, aEntry->ForcePrincipalCheck(), aCORSMode,
                            aTriggeringPrincipal, aCX, aLoadPolicyType,
                            aReferrerInfo))
    return false;

  // data URIs are immutable and by their nature can't leak data, so we can
  // just return true in that case.  Doing so would mean that shift-reload
  // doesn't reload data URI documents/images though (which is handy for
  // debugging during gecko development) so we make an exception in that case.
  nsAutoCString scheme;
  aURI->GetScheme(scheme);
  if (scheme.EqualsLiteral("data") &&
      !(aLoadFlags & nsIRequest::LOAD_BYPASS_CACHE)) {
    return true;
  }

  bool validateRequest = false;

  // If the request's loadId is the same as the aCX, then it is ok to use
  // this one because it has already been validated for this context.
  //
  // XXX: nullptr seems to be a 'special' key value that indicates that NO
  //      validation is required.
  // XXX: we also check the window ID because the loadID() can return a reused
  //      pointer of a document. This can still happen for non-document image
  //      cache entries.
  void* key = (void*)aCX;
  nsCOMPtr<Document> doc = do_QueryInterface(aCX);
  uint64_t innerWindowID = doc ? doc->InnerWindowID() : 0;
  if (request->LoadId() != key || request->InnerWindowID() != innerWindowID) {
    // If we would need to revalidate this entry, but we're being told to
    // bypass the cache, we don't allow this entry to be used.
    if (aLoadFlags & nsIRequest::LOAD_BYPASS_CACHE) {
      return false;
    }

    if (MOZ_UNLIKELY(ChaosMode::isActive(ChaosFeature::ImageCache))) {
      if (ChaosMode::randomUint32LessThan(4) < 1) {
        return false;
      }
    }

    // Determine whether the cache aEntry must be revalidated...
    validateRequest = ShouldRevalidateEntry(aEntry, aLoadFlags, hasExpired);

    MOZ_LOG(gImgLog, LogLevel::Debug,
            ("imgLoader::ValidateEntry validating cache entry. "
             "validateRequest = %d",
             validateRequest));
  } else if (!key && MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
    MOZ_LOG(gImgLog, LogLevel::Debug,
            ("imgLoader::ValidateEntry BYPASSING cache validation for %s "
             "because of NULL LoadID",
             aURI->GetSpecOrDefault().get()));
  }

  // We can't use a cached request if it comes from a different
  // application cache than this load is expecting.
  nsCOMPtr<nsIApplicationCacheContainer> appCacheContainer;
  nsCOMPtr<nsIApplicationCache> requestAppCache;
  nsCOMPtr<nsIApplicationCache> groupAppCache;
  if ((appCacheContainer = do_GetInterface(request->GetRequest()))) {
    appCacheContainer->GetApplicationCache(getter_AddRefs(requestAppCache));
  }
  if ((appCacheContainer = do_QueryInterface(aLoadGroup))) {
    appCacheContainer->GetApplicationCache(getter_AddRefs(groupAppCache));
  }

  if (requestAppCache != groupAppCache) {
    MOZ_LOG(gImgLog, LogLevel::Debug,
            ("imgLoader::ValidateEntry - Unable to use cached imgRequest "
             "[request=%p] because of mismatched application caches\n",
             address_of(request)));
    return false;
  }

  if (validateRequest && aCanMakeNewChannel) {
    LOG_SCOPE(gImgLog, "imgLoader::ValidateRequest |cache hit| must validate");

    return ValidateRequestWithNewChannel(
        request, aURI, aInitialDocumentURI, aReferrerInfo, aLoadGroup,
        aObserver, aCX, aLoadingDocument, innerWindowID, aLoadFlags,
        aLoadPolicyType, aProxyRequest, aTriggeringPrincipal, aCORSMode,
        aNewChannelCreated);
  }

  return !validateRequest;
}

bool imgLoader::RemoveFromCache(const ImageCacheKey& aKey) {
  LOG_STATIC_FUNC_WITH_PARAM(gImgLog, "imgLoader::RemoveFromCache", "uri",
                             aKey.URI());

  imgCacheTable& cache = GetCache(aKey);
  imgCacheQueue& queue = GetCacheQueue(aKey);

  RefPtr<imgCacheEntry> entry;
  cache.Remove(aKey, getter_AddRefs(entry));
  if (entry) {
    MOZ_ASSERT(!entry->Evicted(), "Evicting an already-evicted cache entry!");

    // Entries with no proxies are in the tracker.
    if (entry->HasNoProxies()) {
      if (mCacheTracker) {
        mCacheTracker->RemoveObject(entry);
      }
      queue.Remove(entry);
    }

    entry->SetEvicted(true);

    RefPtr<imgRequest> request = entry->GetRequest();
    request->SetIsInCache(false);
    AddToUncachedImages(request);

    return true;
  }
  return false;
}

bool imgLoader::RemoveFromCache(imgCacheEntry* entry, QueueState aQueueState) {
  LOG_STATIC_FUNC(gImgLog, "imgLoader::RemoveFromCache entry");

  RefPtr<imgRequest> request = entry->GetRequest();
  if (request) {
    const ImageCacheKey& key = request->CacheKey();
    imgCacheTable& cache = GetCache(key);
    imgCacheQueue& queue = GetCacheQueue(key);

    LOG_STATIC_FUNC_WITH_PARAM(gImgLog, "imgLoader::RemoveFromCache",
                               "entry's uri", key.URI());

    cache.Remove(key);

    if (entry->HasNoProxies()) {
      LOG_STATIC_FUNC(gImgLog,
                      "imgLoader::RemoveFromCache removing from tracker");
      if (mCacheTracker) {
        mCacheTracker->RemoveObject(entry);
      }
      // Only search the queue to remove the entry if its possible it might
      // be in the queue.  If we know its not in the queue this would be
      // wasted work.
      MOZ_ASSERT_IF(aQueueState == QueueState::AlreadyRemoved,
                    !queue.Contains(entry));
      if (aQueueState == QueueState::MaybeExists) {
        queue.Remove(entry);
      }
    }

    entry->SetEvicted(true);
    request->SetIsInCache(false);
    AddToUncachedImages(request);

    return true;
  }

  return false;
}

nsresult imgLoader::EvictEntries(imgCacheTable& aCacheToClear) {
  LOG_STATIC_FUNC(gImgLog, "imgLoader::EvictEntries table");

  // We have to make a temporary, since RemoveFromCache removes the element
  // from the queue, invalidating iterators.
  nsTArray<RefPtr<imgCacheEntry> > entries;
  for (auto iter = aCacheToClear.Iter(); !iter.Done(); iter.Next()) {
    RefPtr<imgCacheEntry>& data = iter.Data();
    entries.AppendElement(data);
  }

  for (uint32_t i = 0; i < entries.Length(); ++i) {
    if (!RemoveFromCache(entries[i])) {
      return NS_ERROR_FAILURE;
    }
  }

  MOZ_ASSERT(aCacheToClear.Count() == 0);

  return NS_OK;
}

nsresult imgLoader::EvictEntries(imgCacheQueue& aQueueToClear) {
  LOG_STATIC_FUNC(gImgLog, "imgLoader::EvictEntries queue");

  // We have to make a temporary, since RemoveFromCache removes the element
  // from the queue, invalidating iterators.
  nsTArray<RefPtr<imgCacheEntry> > entries(aQueueToClear.GetNumElements());
  for (auto i = aQueueToClear.begin(); i != aQueueToClear.end(); ++i) {
    entries.AppendElement(*i);
  }

  // Iterate in reverse order to minimize array copying.
  for (auto& entry : entries) {
    if (!RemoveFromCache(entry)) {
      return NS_ERROR_FAILURE;
    }
  }

  MOZ_ASSERT(aQueueToClear.GetNumElements() == 0);

  return NS_OK;
}

void imgLoader::AddToUncachedImages(imgRequest* aRequest) {
  MutexAutoLock lock(mUncachedImagesMutex);
  mUncachedImages.PutEntry(aRequest);
}

void imgLoader::RemoveFromUncachedImages(imgRequest* aRequest) {
  MutexAutoLock lock(mUncachedImagesMutex);
  mUncachedImages.RemoveEntry(aRequest);
}

bool imgLoader::PreferLoadFromCache(nsIURI* aURI) const {
  // If we are trying to load an image from a protocol that doesn't support
  // caching (e.g. thumbnails via the moz-page-thumb:// protocol, or icons via
  // the moz-extension:// protocol), load it directly from the cache to prevent
  // re-decoding the image. See Bug 1373258.
  // TODO: Bug 1406134
  return aURI->SchemeIs("moz-page-thumb") || aURI->SchemeIs("moz-extension");
}

#define LOAD_FLAGS_CACHE_MASK \
  (nsIRequest::LOAD_BYPASS_CACHE | nsIRequest::LOAD_FROM_CACHE)

#define LOAD_FLAGS_VALIDATE_MASK                              \
  (nsIRequest::VALIDATE_ALWAYS | nsIRequest::VALIDATE_NEVER | \
   nsIRequest::VALIDATE_ONCE_PER_SESSION)

NS_IMETHODIMP
imgLoader::LoadImageXPCOM(nsIURI* aURI, nsIURI* aInitialDocumentURI,
                          nsIReferrerInfo* aReferrerInfo,
                          nsIPrincipal* aTriggeringPrincipal,
                          nsILoadGroup* aLoadGroup,
                          imgINotificationObserver* aObserver, nsISupports* aCX,
                          nsLoadFlags aLoadFlags, nsISupports* aCacheKey,
                          nsContentPolicyType aContentPolicyType,
                          imgIRequest** _retval) {
  // Optional parameter, so defaults to 0 (== TYPE_INVALID)
  if (!aContentPolicyType) {
    aContentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE;
  }
  imgRequestProxy* proxy;
  nsCOMPtr<nsINode> node = do_QueryInterface(aCX);
  nsCOMPtr<Document> doc = do_QueryInterface(aCX);
  nsresult rv =
      LoadImage(aURI, aInitialDocumentURI, aReferrerInfo, aTriggeringPrincipal,
                0, aLoadGroup, aObserver, node, doc, aLoadFlags, aCacheKey,
                aContentPolicyType, EmptyString(),
                /* aUseUrgentStartForChannel */ false, &proxy);
  *_retval = proxy;
  return rv;
}

nsresult imgLoader::LoadImage(
    nsIURI* aURI, nsIURI* aInitialDocumentURI, nsIReferrerInfo* aReferrerInfo,
    nsIPrincipal* aTriggeringPrincipal, uint64_t aRequestContextID,
    nsILoadGroup* aLoadGroup, imgINotificationObserver* aObserver,
    nsINode* aContext, Document* aLoadingDocument, nsLoadFlags aLoadFlags,
    nsISupports* aCacheKey, nsContentPolicyType aContentPolicyType,
    const nsAString& initiatorType, bool aUseUrgentStartForChannel,
    imgRequestProxy** _retval) {
  VerifyCacheSizes();

  NS_ASSERTION(aURI, "imgLoader::LoadImage -- NULL URI pointer");

  if (!aURI) {
    return NS_ERROR_NULL_POINTER;
  }

#ifdef MOZ_GECKO_PROFILER
  AUTO_PROFILER_LABEL_DYNAMIC_NSCSTRING("imgLoader::LoadImage", NETWORK,
                                        aURI->GetSpecOrDefault());
#endif

  LOG_SCOPE_WITH_PARAM(gImgLog, "imgLoader::LoadImage", "aURI", aURI);

  *_retval = nullptr;

  RefPtr<imgRequest> request;

  nsresult rv;
  nsLoadFlags requestFlags = nsIRequest::LOAD_NORMAL;

#ifdef DEBUG
  bool isPrivate = false;

  if (aLoadingDocument) {
    isPrivate = nsContentUtils::IsInPrivateBrowsing(aLoadingDocument);
  } else if (aLoadGroup) {
    isPrivate = nsContentUtils::IsInPrivateBrowsing(aLoadGroup);
  }
  MOZ_ASSERT(isPrivate == mRespectPrivacy);

  if (aLoadingDocument) {
    // The given load group should match that of the document if given. If
    // that isn't the case, then we need to add more plumbing to ensure we
    // block the document as well.
    nsCOMPtr<nsILoadGroup> docLoadGroup =
        aLoadingDocument->GetDocumentLoadGroup();
    MOZ_ASSERT(docLoadGroup == aLoadGroup);
  }
#endif

  // Get the default load flags from the loadgroup (if possible)...
  if (aLoadGroup) {
    aLoadGroup->GetLoadFlags(&requestFlags);
    if (PreferLoadFromCache(aURI)) {
      requestFlags |= nsIRequest::LOAD_FROM_CACHE;
    }
  }
  //
  // Merge the default load flags with those passed in via aLoadFlags.
  // Currently, *only* the caching, validation and background load flags
  // are merged...
  //
  // The flags in aLoadFlags take precedence over the default flags!
  //
  if (aLoadFlags & LOAD_FLAGS_CACHE_MASK) {
    // Override the default caching flags...
    requestFlags = (requestFlags & ~LOAD_FLAGS_CACHE_MASK) |
                   (aLoadFlags & LOAD_FLAGS_CACHE_MASK);
  }
  if (aLoadFlags & LOAD_FLAGS_VALIDATE_MASK) {
    // Override the default validation flags...
    requestFlags = (requestFlags & ~LOAD_FLAGS_VALIDATE_MASK) |
                   (aLoadFlags & LOAD_FLAGS_VALIDATE_MASK);
  }
  if (aLoadFlags & nsIRequest::LOAD_BACKGROUND) {
    // Propagate background loading...
    requestFlags |= nsIRequest::LOAD_BACKGROUND;
  }

  int32_t corsmode = imgIRequest::CORS_NONE;
  if (aLoadFlags & imgILoader::LOAD_CORS_ANONYMOUS) {
    corsmode = imgIRequest::CORS_ANONYMOUS;
  } else if (aLoadFlags & imgILoader::LOAD_CORS_USE_CREDENTIALS) {
    corsmode = imgIRequest::CORS_USE_CREDENTIALS;
  }

  RefPtr<imgCacheEntry> entry;

  // Look in the cache for our URI, and then validate it.
  // XXX For now ignore aCacheKey. We will need it in the future
  // for correctly dealing with image load requests that are a result
  // of post data.
  OriginAttributes attrs;
  if (aTriggeringPrincipal) {
    attrs = aTriggeringPrincipal->OriginAttributesRef();
  }
  ImageCacheKey key(aURI, attrs, aLoadingDocument);
  imgCacheTable& cache = GetCache(key);

  if (cache.Get(key, getter_AddRefs(entry)) && entry) {
    bool newChannelCreated = false;
    if (ValidateEntry(entry, aURI, aInitialDocumentURI, aReferrerInfo,
                      aLoadGroup, aObserver, ToSupports(aLoadingDocument),
                      aLoadingDocument, requestFlags, aContentPolicyType, true,
                      &newChannelCreated, _retval, aTriggeringPrincipal,
                      corsmode)) {
      request = entry->GetRequest();

      // If this entry has no proxies, its request has no reference to the
      // entry.
      if (entry->HasNoProxies()) {
        LOG_FUNC_WITH_PARAM(gImgLog,
                            "imgLoader::LoadImage() adding proxyless entry",
                            "uri", key.URI());
        MOZ_ASSERT(!request->HasCacheEntry(),
                   "Proxyless entry's request has cache entry!");
        request->SetCacheEntry(entry);

        if (mCacheTracker && entry->GetExpirationState()->IsTracked()) {
          mCacheTracker->MarkUsed(entry);
        }
      }

      entry->Touch();

      if (!newChannelCreated) {
        // This is ugly but it's needed to report CSP violations. We have 3
        // scenarios:
        // - we don't have cache. We are not in this if() stmt. A new channel is
        //   created and that triggers the CSP checks.
        // - We have a cache entry and this is blocked by CSP directives.
        DebugOnly<bool> shouldLoad =
            ShouldLoadCachedImage(request, ToSupports(aLoadingDocument),
                                  aTriggeringPrincipal, aContentPolicyType,
                                  /* aSendCSPViolationReports */ true);
        MOZ_ASSERT(shouldLoad);
      }
    } else {
      // We can't use this entry. We'll try to load it off the network, and if
      // successful, overwrite the old entry in the cache with a new one.
      entry = nullptr;
    }
  }

  // Keep the channel in this scope, so we can adjust its notificationCallbacks
  // later when we create the proxy.
  nsCOMPtr<nsIChannel> newChannel;
  // If we didn't get a cache hit, we need to load from the network.
  if (!request) {
    LOG_SCOPE(gImgLog, "imgLoader::LoadImage |cache miss|");

    bool forcePrincipalCheck;
    rv = NewImageChannel(getter_AddRefs(newChannel), &forcePrincipalCheck, aURI,
                         aInitialDocumentURI, corsmode, aReferrerInfo,
                         aLoadGroup, mAcceptHeader, requestFlags,
                         aContentPolicyType, aTriggeringPrincipal, aContext,
                         mRespectPrivacy);
    if (NS_FAILED(rv)) {
      return NS_ERROR_FAILURE;
    }

    MOZ_ASSERT(NS_UsePrivateBrowsing(newChannel) == mRespectPrivacy);

    NewRequestAndEntry(forcePrincipalCheck, this, key, getter_AddRefs(request),
                       getter_AddRefs(entry));

    MOZ_LOG(gImgLog, LogLevel::Debug,
            ("[this=%p] imgLoader::LoadImage -- Created new imgRequest"
             " [request=%p]\n",
             this, request.get()));

    nsCOMPtr<nsIClassOfService> cos(do_QueryInterface(newChannel));
    if (cos) {
      if (aUseUrgentStartForChannel) {
        cos->AddClassFlags(nsIClassOfService::UrgentStart);
      }

      if (StaticPrefs::network_http_tailing_enabled() &&
          aContentPolicyType == nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON) {
        cos->AddClassFlags(nsIClassOfService::Throttleable |
                           nsIClassOfService::Tail);
        nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(newChannel));
        if (httpChannel) {
          Unused << httpChannel->SetRequestContextID(aRequestContextID);
        }
      }
    }

    nsCOMPtr<nsILoadGroup> channelLoadGroup;
    newChannel->GetLoadGroup(getter_AddRefs(channelLoadGroup));
    rv = request->Init(aURI, aURI, /* aHadInsecureRedirect = */ false,
                       channelLoadGroup, newChannel, entry,
                       ToSupports(aLoadingDocument), aTriggeringPrincipal,
                       corsmode, aReferrerInfo);
    if (NS_FAILED(rv)) {
      return NS_ERROR_FAILURE;
    }

    // Add the initiator type for this image load
    nsCOMPtr<nsITimedChannel> timedChannel = do_QueryInterface(newChannel);
    if (timedChannel) {
      timedChannel->SetInitiatorType(initiatorType);
    }

    // create the proxy listener
    nsCOMPtr<nsIStreamListener> listener = new ProxyListener(request.get());

    MOZ_LOG(gImgLog, LogLevel::Debug,
            ("[this=%p] imgLoader::LoadImage -- Calling channel->AsyncOpen()\n",
             this));

    mozilla::net::PredictorLearn(aURI, aInitialDocumentURI,
                                 nsINetworkPredictor::LEARN_LOAD_SUBRESOURCE,
                                 aLoadGroup);

    nsresult openRes = newChannel->AsyncOpen(listener);

    if (NS_FAILED(openRes)) {
      MOZ_LOG(
          gImgLog, LogLevel::Debug,
          ("[this=%p] imgLoader::LoadImage -- AsyncOpen() failed: 0x%" PRIx32
           "\n",
           this, static_cast<uint32_t>(openRes)));
      request->CancelAndAbort(openRes);
      return openRes;
    }

    // Try to add the new request into the cache.
    PutIntoCache(key, entry);
  } else {
    LOG_MSG_WITH_PARAM(gImgLog, "imgLoader::LoadImage |cache hit|", "request",
                       request);
  }

  // If we didn't get a proxy when validating the cache entry, we need to
  // create one.
  if (!*_retval) {
    // ValidateEntry() has three return values: "Is valid," "might be valid --
    // validating over network", and "not valid." If we don't have a _retval,
    // we know ValidateEntry is not validating over the network, so it's safe
    // to SetLoadId here because we know this request is valid for this context.
    //
    // Note, however, that this doesn't guarantee the behaviour we want (one
    // URL maps to the same image on a page) if we load the same image in a
    // different tab (see bug 528003), because its load id will get re-set, and
    // that'll cause us to validate over the network.
    request->SetLoadId(aLoadingDocument);

    LOG_MSG(gImgLog, "imgLoader::LoadImage", "creating proxy request.");
    rv = CreateNewProxyForRequest(request, aLoadGroup, aLoadingDocument,
                                  aObserver, requestFlags, _retval);
    if (NS_FAILED(rv)) {
      return rv;
    }

    imgRequestProxy* proxy = *_retval;

    // Make sure that OnStatus/OnProgress calls have the right request set, if
    // we did create a channel here.
    if (newChannel) {
      nsCOMPtr<nsIInterfaceRequestor> requestor(
          new nsProgressNotificationProxy(newChannel, proxy));
      if (!requestor) {
        return NS_ERROR_OUT_OF_MEMORY;
      }
      newChannel->SetNotificationCallbacks(requestor);
    }

    // Note that it's OK to add here even if the request is done.  If it is,
    // it'll send a OnStopRequest() to the proxy in imgRequestProxy::Notify and
    // the proxy will be removed from the loadgroup.
    proxy->AddToLoadGroup();

    // If we're loading off the network, explicitly don't notify our proxy,
    // because necko (or things called from necko, such as imgCacheValidator)
    // are going to call our notifications asynchronously, and we can't make it
    // further asynchronous because observers might rely on imagelib completing
    // its work between the channel's OnStartRequest and OnStopRequest.
    if (!newChannel) {
      proxy->NotifyListener();
    }

    return rv;
  }

  NS_ASSERTION(*_retval, "imgLoader::LoadImage -- no return value");

  return NS_OK;
}

NS_IMETHODIMP
imgLoader::LoadImageWithChannelXPCOM(nsIChannel* channel,
                                     imgINotificationObserver* aObserver,
                                     nsISupports* aCX,
                                     nsIStreamListener** listener,
                                     imgIRequest** _retval) {
  nsresult result;
  imgRequestProxy* proxy;
  result = LoadImageWithChannel(channel, aObserver, aCX, listener, &proxy);
  *_retval = proxy;
  return result;
}

nsresult imgLoader::LoadImageWithChannel(nsIChannel* channel,
                                         imgINotificationObserver* aObserver,
                                         nsISupports* aCX,
                                         nsIStreamListener** listener,
                                         imgRequestProxy** _retval) {
  NS_ASSERTION(channel,
               "imgLoader::LoadImageWithChannel -- NULL channel pointer");

  MOZ_ASSERT(NS_UsePrivateBrowsing(channel) == mRespectPrivacy);

  LOG_SCOPE(gImgLog, "imgLoader::LoadImageWithChannel");
  RefPtr<imgRequest> request;

  nsCOMPtr<nsIURI> uri;
  channel->GetURI(getter_AddRefs(uri));
  nsCOMPtr<Document> doc = do_QueryInterface(aCX);

  NS_ENSURE_TRUE(channel, NS_ERROR_FAILURE);
  nsCOMPtr<nsILoadInfo> loadInfo = channel->LoadInfo();

  OriginAttributes attrs = loadInfo->GetOriginAttributes();

  ImageCacheKey key(uri, attrs, doc);

  nsLoadFlags requestFlags = nsIRequest::LOAD_NORMAL;
  channel->GetLoadFlags(&requestFlags);

  if (PreferLoadFromCache(uri)) {
    requestFlags |= nsIRequest::LOAD_FROM_CACHE;
  }

  RefPtr<imgCacheEntry> entry;

  if (requestFlags & nsIRequest::LOAD_BYPASS_CACHE) {
    RemoveFromCache(key);
  } else {
    // Look in the cache for our URI, and then validate it.
    // XXX For now ignore aCacheKey. We will need it in the future
    // for correctly dealing with image load requests that are a result
    // of post data.
    imgCacheTable& cache = GetCache(key);
    if (cache.Get(key, getter_AddRefs(entry)) && entry) {
      // We don't want to kick off another network load. So we ask
      // ValidateEntry to only do validation without creating a new proxy. If
      // it says that the entry isn't valid any more, we'll only use the entry
      // we're getting if the channel is loading from the cache anyways.
      //
      // XXX -- should this be changed? it's pretty much verbatim from the old
      // code, but seems nonsensical.
      //
      // Since aCanMakeNewChannel == false, we don't need to pass content policy
      // type/principal/etc

      nsCOMPtr<nsILoadInfo> loadInfo = channel->LoadInfo();
      // if there is a loadInfo, use the right contentType, otherwise
      // default to the internal image type
      nsContentPolicyType policyType = loadInfo->InternalContentPolicyType();

      if (ValidateEntry(entry, uri, nullptr, nullptr, nullptr, aObserver, aCX,
                        doc, requestFlags, policyType, false, nullptr, nullptr,
                        nullptr, imgIRequest::CORS_NONE)) {
        request = entry->GetRequest();
      } else {
        nsCOMPtr<nsICacheInfoChannel> cacheChan(do_QueryInterface(channel));
        bool bUseCacheCopy;

        if (cacheChan) {
          cacheChan->IsFromCache(&bUseCacheCopy);
        } else {
          bUseCacheCopy = false;
        }

        if (!bUseCacheCopy) {
          entry = nullptr;
        } else {
          request = entry->GetRequest();
        }
      }

      if (request && entry) {
        // If this entry has no proxies, its request has no reference to
        // the entry.
        if (entry->HasNoProxies()) {
          LOG_FUNC_WITH_PARAM(
              gImgLog,
              "imgLoader::LoadImageWithChannel() adding proxyless entry", "uri",
              key.URI());
          MOZ_ASSERT(!request->HasCacheEntry(),
                     "Proxyless entry's request has cache entry!");
          request->SetCacheEntry(entry);

          if (mCacheTracker && entry->GetExpirationState()->IsTracked()) {
            mCacheTracker->MarkUsed(entry);
          }
        }
      }
    }
  }

  nsCOMPtr<nsILoadGroup> loadGroup;
  channel->GetLoadGroup(getter_AddRefs(loadGroup));

#ifdef DEBUG
  if (doc) {
    // The load group of the channel should always match that of the
    // document if given. If that isn't the case, then we need to add more
    // plumbing to ensure we block the document as well.
    nsCOMPtr<nsILoadGroup> docLoadGroup = doc->GetDocumentLoadGroup();
    MOZ_ASSERT(docLoadGroup == loadGroup);
  }
#endif

  // Filter out any load flags not from nsIRequest
  requestFlags &= nsIRequest::LOAD_REQUESTMASK;

  nsresult rv = NS_OK;
  if (request) {
    // we have this in our cache already.. cancel the current (document) load

    // this should fire an OnStopRequest
    channel->Cancel(NS_ERROR_PARSED_DATA_CACHED);

    *listener = nullptr;  // give them back a null nsIStreamListener

    rv = CreateNewProxyForRequest(request, loadGroup, doc, aObserver,
                                  requestFlags, _retval);
    static_cast<imgRequestProxy*>(*_retval)->NotifyListener();
  } else {
    // We use originalURI here to fulfil the imgIRequest contract on GetURI.
    nsCOMPtr<nsIURI> originalURI;
    channel->GetOriginalURI(getter_AddRefs(originalURI));

    // XXX(seth): We should be able to just use |key| here, except that |key| is
    // constructed above with the *current URI* and not the *original URI*. I'm
    // pretty sure this is a bug, and it's preventing us from ever getting a
    // cache hit in LoadImageWithChannel when redirects are involved.
    ImageCacheKey originalURIKey(originalURI, attrs, doc);

    // Default to doing a principal check because we don't know who
    // started that load and whether their principal ended up being
    // inherited on the channel.
    NewRequestAndEntry(/* aForcePrincipalCheckForCacheEntry = */ true, this,
                       originalURIKey, getter_AddRefs(request),
                       getter_AddRefs(entry));

    // No principal specified here, because we're not passed one.
    // In LoadImageWithChannel, the redirects that may have been
    // associated with this load would have gone through necko.
    // We only have the final URI in ImageLib and hence don't know
    // if the request went through insecure redirects.  But if it did,
    // the necko cache should have handled that (since all necko cache hits
    // including the redirects will go through content policy).  Hence, we
    // can set aHadInsecureRedirect to false here.
    rv = request->Init(originalURI, uri, /* aHadInsecureRedirect = */ false,
                       channel, channel, entry, aCX, nullptr,
                       imgIRequest::CORS_NONE, nullptr);
    NS_ENSURE_SUCCESS(rv, rv);

    RefPtr<ProxyListener> pl =
        new ProxyListener(static_cast<nsIStreamListener*>(request.get()));
    pl.forget(listener);

    // Try to add the new request into the cache.
    PutIntoCache(originalURIKey, entry);

    rv = CreateNewProxyForRequest(request, loadGroup, doc, aObserver,
                                  requestFlags, _retval);

    // Explicitly don't notify our proxy, because we're loading off the
    // network, and necko (or things called from necko, such as
    // imgCacheValidator) are going to call our notifications asynchronously,
    // and we can't make it further asynchronous because observers might rely
    // on imagelib completing its work between the channel's OnStartRequest and
    // OnStopRequest.
  }

  if (NS_FAILED(rv)) {
    return rv;
  }

  (*_retval)->AddToLoadGroup();
  return rv;
}

bool imgLoader::SupportImageWithMimeType(const char* aMimeType,
                                         AcceptedMimeTypes aAccept
                                         /* = AcceptedMimeTypes::IMAGES */) {
  nsAutoCString mimeType(aMimeType);
  ToLowerCase(mimeType);

  if (aAccept == AcceptedMimeTypes::IMAGES_AND_DOCUMENTS &&
      mimeType.EqualsLiteral("image/svg+xml")) {
    return true;
  }

  DecoderType type = DecoderFactory::GetDecoderType(mimeType.get());
  return type != DecoderType::UNKNOWN;
}

NS_IMETHODIMP
imgLoader::GetMIMETypeFromContent(nsIRequest* aRequest,
                                  const uint8_t* aContents, uint32_t aLength,
                                  nsACString& aContentType) {
  nsCOMPtr<nsIChannel> channel(do_QueryInterface(aRequest));
  if (channel) {
    nsCOMPtr<nsILoadInfo> loadInfo = channel->LoadInfo();
    if (loadInfo->GetSkipContentSniffing()) {
      return NS_ERROR_NOT_AVAILABLE;
    }
  }
  return GetMimeTypeFromContent((const char*)aContents, aLength, aContentType);
}

/* static */
nsresult imgLoader::GetMimeTypeFromContent(const char* aContents,
                                           uint32_t aLength,
                                           nsACString& aContentType) {
  /* Is it a GIF? */
  if (aLength >= 6 &&
      (!strncmp(aContents, "GIF87a", 6) || !strncmp(aContents, "GIF89a", 6))) {
    aContentType.AssignLiteral(IMAGE_GIF);

    /* or a PNG? */
  } else if (aLength >= 8 && ((unsigned char)aContents[0] == 0x89 &&
                              (unsigned char)aContents[1] == 0x50 &&
                              (unsigned char)aContents[2] == 0x4E &&
                              (unsigned char)aContents[3] == 0x47 &&
                              (unsigned char)aContents[4] == 0x0D &&
                              (unsigned char)aContents[5] == 0x0A &&
                              (unsigned char)aContents[6] == 0x1A &&
                              (unsigned char)aContents[7] == 0x0A)) {
    aContentType.AssignLiteral(IMAGE_PNG);

    /* maybe a JPEG (JFIF)? */
    /* JFIF files start with SOI APP0 but older files can start with SOI DQT
     * so we test for SOI followed by any marker, i.e. FF D8 FF
     * this will also work for SPIFF JPEG files if they appear in the future.
     *
     * (JFIF is 0XFF 0XD8 0XFF 0XE0 <skip 2> 0X4A 0X46 0X49 0X46 0X00)
     */
  } else if (aLength >= 3 && ((unsigned char)aContents[0]) == 0xFF &&
             ((unsigned char)aContents[1]) == 0xD8 &&
             ((unsigned char)aContents[2]) == 0xFF) {
    aContentType.AssignLiteral(IMAGE_JPEG);

    /* or how about ART? */
    /* ART begins with JG (4A 47). Major version offset 2.
     * Minor version offset 3. Offset 4 must be nullptr.
     */
  } else if (aLength >= 5 && ((unsigned char)aContents[0]) == 0x4a &&
             ((unsigned char)aContents[1]) == 0x47 &&
             ((unsigned char)aContents[4]) == 0x00) {
    aContentType.AssignLiteral(IMAGE_ART);

  } else if (aLength >= 2 && !strncmp(aContents, "BM", 2)) {
    aContentType.AssignLiteral(IMAGE_BMP);

    // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
    // CURs begin with 2-byte 0 followed by 2-byte 2.
  } else if (aLength >= 4 && (!memcmp(aContents, "\000\000\001\000", 4) ||
                              !memcmp(aContents, "\000\000\002\000", 4))) {
    aContentType.AssignLiteral(IMAGE_ICO);

    // WebPs always begin with RIFF, a 32-bit length, and WEBP.
  } else if (aLength >= 12 && !memcmp(aContents, "RIFF", 4) &&
             !memcmp(aContents + 8, "WEBP", 4)) {
    aContentType.AssignLiteral(IMAGE_WEBP);

  } else {
    /* none of the above?  I give up */
    return NS_ERROR_NOT_AVAILABLE;
  }

  return NS_OK;
}

/**
 * proxy stream listener class used to handle multipart/x-mixed-replace
 */

#include "nsIRequest.h"
#include "nsIStreamConverterService.h"

NS_IMPL_ISUPPORTS(ProxyListener, nsIStreamListener,
                  nsIThreadRetargetableStreamListener, nsIRequestObserver)

ProxyListener::ProxyListener(nsIStreamListener* dest) : mDestListener(dest) {
  /* member initializers and constructor code */
}

ProxyListener::~ProxyListener() { /* destructor code */
}

/** nsIRequestObserver methods **/

NS_IMETHODIMP
ProxyListener::OnStartRequest(nsIRequest* aRequest) {
  if (!mDestListener) {
    return NS_ERROR_FAILURE;
  }

  nsCOMPtr<nsIChannel> channel(do_QueryInterface(aRequest));
  if (channel) {
    // We need to set the initiator type for the image load
    nsCOMPtr<nsITimedChannel> timedChannel = do_QueryInterface(channel);
    if (timedChannel) {
      nsAutoString type;
      timedChannel->GetInitiatorType(type);
      if (type.IsEmpty()) {
        timedChannel->SetInitiatorType(NS_LITERAL_STRING("img"));
      }
    }

    nsAutoCString contentType;
    nsresult rv = channel->GetContentType(contentType);

    if (!contentType.IsEmpty()) {
      /* If multipart/x-mixed-replace content, we'll insert a MIME decoder
         in the pipeline to handle the content and pass it along to our
         original listener.
       */
      if (NS_LITERAL_CSTRING("multipart/x-mixed-replace").Equals(contentType)) {
        nsCOMPtr<nsIStreamConverterService> convServ(
            do_GetService("@mozilla.org/streamConverters;1", &rv));
        if (NS_SUCCEEDED(rv)) {
          nsCOMPtr<nsIStreamListener> toListener(mDestListener);
          nsCOMPtr<nsIStreamListener> fromListener;

          rv = convServ->AsyncConvertData("multipart/x-mixed-replace", "*/*",
                                          toListener, nullptr,
                                          getter_AddRefs(fromListener));
          if (NS_SUCCEEDED(rv)) {
            mDestListener = fromListener;
          }
        }
      }
    }
  }

  return mDestListener->OnStartRequest(aRequest);
}

NS_IMETHODIMP
ProxyListener::OnStopRequest(nsIRequest* aRequest, nsresult status) {
  if (!mDestListener) {
    return NS_ERROR_FAILURE;
  }

  return mDestListener->OnStopRequest(aRequest, status);
}

/** nsIStreamListener methods **/

NS_IMETHODIMP
ProxyListener::OnDataAvailable(nsIRequest* aRequest, nsIInputStream* inStr,
                               uint64_t sourceOffset, uint32_t count) {
  if (!mDestListener) {
    return NS_ERROR_FAILURE;
  }

  return mDestListener->OnDataAvailable(aRequest, inStr, sourceOffset, count);
}

/** nsThreadRetargetableStreamListener methods **/
NS_IMETHODIMP
ProxyListener::CheckListenerChain() {
  NS_ASSERTION(NS_IsMainThread(), "Should be on the main thread!");
  nsresult rv = NS_OK;
  nsCOMPtr<nsIThreadRetargetableStreamListener> retargetableListener =
      do_QueryInterface(mDestListener, &rv);
  if (retargetableListener) {
    rv = retargetableListener->CheckListenerChain();
  }
  MOZ_LOG(
      gImgLog, LogLevel::Debug,
      ("ProxyListener::CheckListenerChain %s [this=%p listener=%p rv=%" PRIx32
       "]",
       (NS_SUCCEEDED(rv) ? "success" : "failure"), this,
       (nsIStreamListener*)mDestListener, static_cast<uint32_t>(rv)));
  return rv;
}

/**
 * http validate class.  check a channel for a 304
 */

NS_IMPL_ISUPPORTS(imgCacheValidator, nsIStreamListener, nsIRequestObserver,
                  nsIThreadRetargetableStreamListener, nsIChannelEventSink,
                  nsIInterfaceRequestor, nsIAsyncVerifyRedirectCallback)

imgCacheValidator::imgCacheValidator(nsProgressNotificationProxy* progress,
                                     imgLoader* loader, imgRequest* request,
                                     nsISupports* aContext,
                                     uint64_t aInnerWindowId,
                                     bool forcePrincipalCheckForCacheEntry)
    : mProgressProxy(progress),
      mRequest(request),
      mContext(aContext),
      mInnerWindowId(aInnerWindowId),
      mImgLoader(loader),
      mHadInsecureRedirect(false) {
  NewRequestAndEntry(forcePrincipalCheckForCacheEntry, loader,
                     mRequest->CacheKey(), getter_AddRefs(mNewRequest),
                     getter_AddRefs(mNewEntry));
}

imgCacheValidator::~imgCacheValidator() {
  if (mRequest) {
    // If something went wrong, and we never unblocked the requests waiting on
    // validation, now is our last chance. We will cancel the new request and
    // switch the waiting proxies to it.
    UpdateProxies(/* aCancelRequest */ true, /* aSyncNotify */ false);
  }
}

void imgCacheValidator::AddProxy(imgRequestProxy* aProxy) {
  // aProxy needs to be in the loadgroup since we're validating from
  // the network.
  aProxy->AddToLoadGroup();

  mProxies.AppendElement(aProxy);
}

void imgCacheValidator::RemoveProxy(imgRequestProxy* aProxy) {
  mProxies.RemoveElement(aProxy);
}

void imgCacheValidator::UpdateProxies(bool aCancelRequest, bool aSyncNotify) {
  MOZ_ASSERT(mRequest);

  // Clear the validator before updating the proxies. The notifications may
  // clone an existing request, and its state could be inconsistent.
  mRequest->SetValidator(nullptr);
  mRequest = nullptr;

  // If an error occurred, we will want to cancel the new request, and make the
  // validating proxies point to it. Any proxies still bound to the original
  // request which are not validating should remain untouched.
  if (aCancelRequest) {
    MOZ_ASSERT(mNewRequest);
    mNewRequest->CancelAndAbort(NS_BINDING_ABORTED);
  }

  // We have finished validating the request, so we can safely take ownership
  // of the proxy list. imgRequestProxy::SyncNotifyListener can mutate the list
  // if imgRequestProxy::CancelAndForgetObserver is called by its owner. Note
  // that any potential notifications should still be suppressed in
  // imgRequestProxy::ChangeOwner because we haven't cleared the validating
  // flag yet, and thus they will remain deferred.
  AutoTArray<RefPtr<imgRequestProxy>, 4> proxies(std::move(mProxies));

  for (auto& proxy : proxies) {
    // First update the state of all proxies before notifying any of them
    // to ensure a consistent state (e.g. in case the notification causes
    // other proxies to be touched indirectly.)
    MOZ_ASSERT(proxy->IsValidating());
    MOZ_ASSERT(proxy->NotificationsDeferred(),
               "Proxies waiting on cache validation should be "
               "deferring notifications!");
    if (mNewRequest) {
      proxy->ChangeOwner(mNewRequest);
    }
    proxy->ClearValidating();
  }

  mNewRequest = nullptr;
  mNewEntry = nullptr;

  for (auto& proxy : proxies) {
    if (aSyncNotify) {
      // Notify synchronously, because the caller knows we are already in an
      // asynchronously-called function (e.g. OnStartRequest).
      proxy->SyncNotifyListener();
    } else {
      // Notify asynchronously, because the caller does not know our current
      // call state (e.g. ~imgCacheValidator).
      proxy->NotifyListener();
    }
  }
}

/** nsIRequestObserver methods **/

NS_IMETHODIMP
imgCacheValidator::OnStartRequest(nsIRequest* aRequest) {
  // We may be holding on to a document, so ensure that it's released.
  nsCOMPtr<nsISupports> context = mContext.forget();

  // If for some reason we don't still have an existing request (probably
  // because OnStartRequest got delivered more than once), just bail.
  if (!mRequest) {
    MOZ_ASSERT_UNREACHABLE("OnStartRequest delivered more than once?");
    aRequest->Cancel(NS_BINDING_ABORTED);
    return NS_ERROR_FAILURE;
  }

  // If this request is coming from cache and has the same URI as our
  // imgRequest, the request all our proxies are pointing at is valid, and all
  // we have to do is tell them to notify their listeners.
  nsCOMPtr<nsICacheInfoChannel> cacheChan(do_QueryInterface(aRequest));
  nsCOMPtr<nsIChannel> channel(do_QueryInterface(aRequest));
  if (cacheChan && channel && !mRequest->CacheChanged(aRequest)) {
    bool isFromCache = false;
    cacheChan->IsFromCache(&isFromCache);

    nsCOMPtr<nsIURI> channelURI;
    channel->GetURI(getter_AddRefs(channelURI));

    nsCOMPtr<nsIURI> finalURI;
    mRequest->GetFinalURI(getter_AddRefs(finalURI));

    bool sameURI = false;
    if (channelURI && finalURI) {
      channelURI->Equals(finalURI, &sameURI);
    }

    if (isFromCache && sameURI) {
      // We don't need to load this any more.
      aRequest->Cancel(NS_BINDING_ABORTED);
      mNewRequest = nullptr;

      // Clear the validator before updating the proxies. The notifications may
      // clone an existing request, and its state could be inconsistent.
      mRequest->SetLoadId(context);
      mRequest->SetInnerWindowID(mInnerWindowId);
      UpdateProxies(/* aCancelRequest */ false, /* aSyncNotify */ true);
      return NS_OK;
    }
  }

  // We can't load out of cache. We have to create a whole new request for the
  // data that's coming in off the channel.
  nsCOMPtr<nsIURI> uri;
  mRequest->GetURI(getter_AddRefs(uri));

  LOG_MSG_WITH_PARAM(gImgLog,
                     "imgCacheValidator::OnStartRequest creating new request",
                     "uri", uri);

  int32_t corsmode = mRequest->GetCORSMode();
  nsCOMPtr<nsIReferrerInfo> referrerInfo = mRequest->GetReferrerInfo();
  nsCOMPtr<nsIPrincipal> triggeringPrincipal =
      mRequest->GetTriggeringPrincipal();

  // Doom the old request's cache entry
  mRequest->RemoveFromCache();

  // We use originalURI here to fulfil the imgIRequest contract on GetURI.
  nsCOMPtr<nsIURI> originalURI;
  channel->GetOriginalURI(getter_AddRefs(originalURI));
  nsresult rv = mNewRequest->Init(originalURI, uri, mHadInsecureRedirect,
                                  aRequest, channel, mNewEntry, context,
                                  triggeringPrincipal, corsmode, referrerInfo);
  if (NS_FAILED(rv)) {
    UpdateProxies(/* aCancelRequest */ true, /* aSyncNotify */ true);
    return rv;
  }

  mDestListener = new ProxyListener(mNewRequest);

  // Try to add the new request into the cache. Note that the entry must be in
  // the cache before the proxies' ownership changes, because adding a proxy
  // changes the caching behaviour for imgRequests.
  mImgLoader->PutIntoCache(mNewRequest->CacheKey(), mNewEntry);
  UpdateProxies(/* aCancelRequest */ false, /* aSyncNotify */ true);
  return mDestListener->OnStartRequest(aRequest);
}

NS_IMETHODIMP
imgCacheValidator::OnStopRequest(nsIRequest* aRequest, nsresult status) {
  // Be sure we've released the document that we may have been holding on to.
  mContext = nullptr;

  if (!mDestListener) {
    return NS_OK;
  }

  return mDestListener->OnStopRequest(aRequest, status);
}

/** nsIStreamListener methods **/

NS_IMETHODIMP
imgCacheValidator::OnDataAvailable(nsIRequest* aRequest, nsIInputStream* inStr,
                                   uint64_t sourceOffset, uint32_t count) {
  if (!mDestListener) {
    // XXX see bug 113959
    uint32_t _retval;
    inStr->ReadSegments(NS_DiscardSegment, nullptr, count, &_retval);
    return NS_OK;
  }

  return mDestListener->OnDataAvailable(aRequest, inStr, sourceOffset, count);
}

/** nsIThreadRetargetableStreamListener methods **/

NS_IMETHODIMP
imgCacheValidator::CheckListenerChain() {
  NS_ASSERTION(NS_IsMainThread(), "Should be on the main thread!");
  nsresult rv = NS_OK;
  nsCOMPtr<nsIThreadRetargetableStreamListener> retargetableListener =
      do_QueryInterface(mDestListener, &rv);
  if (retargetableListener) {
    rv = retargetableListener->CheckListenerChain();
  }
  MOZ_LOG(
      gImgLog, LogLevel::Debug,
      ("[this=%p] imgCacheValidator::CheckListenerChain -- rv %" PRId32 "=%s",
       this, static_cast<uint32_t>(rv),
       NS_SUCCEEDED(rv) ? "succeeded" : "failed"));
  return rv;
}

/** nsIInterfaceRequestor methods **/

NS_IMETHODIMP
imgCacheValidator::GetInterface(const nsIID& aIID, void** aResult) {
  if (aIID.Equals(NS_GET_IID(nsIChannelEventSink))) {
    return QueryInterface(aIID, aResult);
  }

  return mProgressProxy->GetInterface(aIID, aResult);
}

// These functions are materially the same as the same functions in imgRequest.
// We duplicate them because we're verifying whether cache loads are necessary,
// not unconditionally loading.

/** nsIChannelEventSink methods **/
NS_IMETHODIMP
imgCacheValidator::AsyncOnChannelRedirect(
    nsIChannel* oldChannel, nsIChannel* newChannel, uint32_t flags,
    nsIAsyncVerifyRedirectCallback* callback) {
  // Note all cache information we get from the old channel.
  mNewRequest->SetCacheValidation(mNewEntry, oldChannel);

  // If the previous URI is a non-HTTPS URI, record that fact for later use by
  // security code, which needs to know whether there is an insecure load at any
  // point in the redirect chain.
  nsCOMPtr<nsIURI> oldURI;
  bool schemeLocal = false;
  if (NS_FAILED(oldChannel->GetURI(getter_AddRefs(oldURI))) ||
      NS_FAILED(NS_URIChainHasFlags(
          oldURI, nsIProtocolHandler::URI_IS_LOCAL_RESOURCE, &schemeLocal)) ||
      (!oldURI->SchemeIs("https") && !oldURI->SchemeIs("chrome") &&
       !schemeLocal)) {
    mHadInsecureRedirect = true;
  }

  // Prepare for callback
  mRedirectCallback = callback;
  mRedirectChannel = newChannel;

  return mProgressProxy->AsyncOnChannelRedirect(oldChannel, newChannel, flags,
                                                this);
}

NS_IMETHODIMP
imgCacheValidator::OnRedirectVerifyCallback(nsresult aResult) {
  // If we've already been told to abort, just do so.
  if (NS_FAILED(aResult)) {
    mRedirectCallback->OnRedirectVerifyCallback(aResult);
    mRedirectCallback = nullptr;
    mRedirectChannel = nullptr;
    return NS_OK;
  }

  // make sure we have a protocol that returns data rather than opens
  // an external application, e.g. mailto:
  nsCOMPtr<nsIURI> uri;
  mRedirectChannel->GetURI(getter_AddRefs(uri));
  bool doesNotReturnData = false;
  NS_URIChainHasFlags(uri, nsIProtocolHandler::URI_DOES_NOT_RETURN_DATA,
                      &doesNotReturnData);

  nsresult result = NS_OK;

  if (doesNotReturnData) {
    result = NS_ERROR_ABORT;
  }

  mRedirectCallback->OnRedirectVerifyCallback(result);
  mRedirectCallback = nullptr;
  mRedirectChannel = nullptr;
  return NS_OK;
}