Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 11190 insertions, 0 deletions

diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
new file mode 100644
index 0000000000..fd1dc60463
--- /dev/null
+++ b/dom/base/nsContentUtils.cpp
@@ -0,0 +1,11190 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A namespace class for static layout utilities. */
+
+#include "nsContentUtils.h"
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <functional>
+#include <new>
+#include <utility>
+#include "BrowserChild.h"
+#include "DecoderTraits.h"
+#include "ErrorList.h"
+#include "HTMLSplitOnSpacesTokenizer.h"
+#include "ImageOps.h"
+#include "InProcessBrowserChildMessageManager.h"
+#include "MainThreadUtils.h"
+#include "PLDHashTable.h"
+#include "ReferrerInfo.h"
+#include "ScopedNSSTypes.h"
+#include "ThirdPartyUtil.h"
+#include "Units.h"
+#include "chrome/common/ipc_message.h"
+#include "gfxDrawable.h"
+#include "harfbuzz/hb.h"
+#include "imgICache.h"
+#include "imgIContainer.h"
+#include "imgILoader.h"
+#include "imgIRequest.h"
+#include "imgLoader.h"
+#include "js/Array.h"
+#include "js/ArrayBuffer.h"
+#include "js/BuildId.h"
+#include "js/GCAPI.h"
+#include "js/Id.h"
+#include "js/JSON.h"
+#include "js/PropertyAndElement.h"  // JS_DefineElement, JS_GetProperty
+#include "js/PropertyDescriptor.h"
+#include "js/Realm.h"
+#include "js/RegExp.h"
+#include "js/RegExpFlags.h"
+#include "js/RootingAPI.h"
+#include "js/TypeDecls.h"
+#include "js/Value.h"
+#include "js/Wrapper.h"
+#include "jsapi.h"
+#include "jsfriendapi.h"
+#include "mozAutoDocUpdate.h"
+#include "mozIDOMWindow.h"
+#include "nsIOService.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/ArrayIterator.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/AsyncEventDispatcher.h"
+#include "mozilla/AtomArray.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/AutoTimelineMarker.h"
+#include "mozilla/BackgroundHangMonitor.h"
+#include "mozilla/Base64.h"
+#include "mozilla/BasePrincipal.h"
+#include "mozilla/BasicEvents.h"
+#include "mozilla/BloomFilter.h"
+#include "mozilla/CORSMode.h"
+#include "mozilla/CallState.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/Components.h"
+#include "mozilla/ContentBlockingAllowList.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/EventListenerManager.h"
+#include "mozilla/EventQueue.h"
+#include "mozilla/EventStateManager.h"
+#include "mozilla/FlushType.h"
+#include "mozilla/FOGIPC.h"
+#include "mozilla/HTMLEditor.h"
+#include "mozilla/HangAnnotations.h"
+#include "mozilla/IMEStateManager.h"
+#include "mozilla/InputEventOptions.h"
+#include "mozilla/InternalMutationEvent.h"
+#include "mozilla/Latin1.h"
+#include "mozilla/Likely.h"
+#include "mozilla/LoadInfo.h"
+#include "mozilla/Logging.h"
+#include "mozilla/MacroForEach.h"
+#include "mozilla/ManualNAC.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/MediaFeatureChange.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/NotNull.h"
+#include "mozilla/NullPrincipal.h"
+#include "mozilla/OriginAttributes.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/ProfilerRunnable.h"
+#include "mozilla/RangeBoundary.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/Result.h"
+#include "mozilla/ResultExtensions.h"
+#include "mozilla/ScrollbarPreferences.h"
+#include "mozilla/Span.h"
+#include "mozilla/StaticAnalysisFunctions.h"
+#include "mozilla/StaticPrefs_browser.h"
+#include "mozilla/StaticPrefs_dom.h"
+#ifdef FUZZING
+#  include "mozilla/StaticPrefs_fuzzing.h"
+#endif
+#include "mozilla/StaticPrefs_nglayout.h"
+#include "mozilla/StaticPrefs_privacy.h"
+#include "mozilla/StaticPrefs_test.h"
+#include "mozilla/StaticPrefs_ui.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/TaskCategory.h"
+#include "mozilla/TextControlState.h"
+#include "mozilla/TextEditor.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+#include "mozilla/Variant.h"
+#include "mozilla/ViewportUtils.h"
+#include "mozilla/dom/AncestorIterator.h"
+#include "mozilla/dom/AutoEntryScript.h"
+#include "mozilla/dom/AutocompleteInfoBinding.h"
+#include "mozilla/dom/AutoSuppressEventHandlingAndSuspend.h"
+#include "mozilla/dom/BindingDeclarations.h"
+#include "mozilla/dom/BindingUtils.h"
+#include "mozilla/dom/BlobImpl.h"
+#include "mozilla/dom/BlobURLProtocolHandler.h"
+#include "mozilla/dom/BorrowedAttrInfo.h"
+#include "mozilla/dom/BrowserBridgeParent.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/BrowsingContext.h"
+#include "mozilla/dom/BrowsingContextGroup.h"
+#include "mozilla/dom/CallbackFunction.h"
+#include "mozilla/dom/CallbackObject.h"
+#include "mozilla/dom/ChromeMessageBroadcaster.h"
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/ContentFrameMessageManager.h"
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/dom/CustomElementRegistry.h"
+#include "mozilla/dom/CustomElementRegistryBinding.h"
+#include "mozilla/dom/DOMArena.h"
+#include "mozilla/dom/DOMException.h"
+#include "mozilla/dom/DOMExceptionBinding.h"
+#include "mozilla/dom/DOMSecurityMonitor.h"
+#include "mozilla/dom/DOMTypes.h"
+#include "mozilla/dom/DataTransfer.h"
+#include "mozilla/dom/DocGroup.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/DocumentFragment.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/ElementBinding.h"
+#include "mozilla/dom/ElementInlines.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/dom/EventTarget.h"
+#include "mozilla/dom/FileBlobImpl.h"
+#include "mozilla/dom/FileSystemSecurity.h"
+#include "mozilla/dom/FilteredNodeIterator.h"
+#include "mozilla/dom/FragmentOrElement.h"
+#include "mozilla/dom/FromParser.h"
+#include "mozilla/dom/HTMLFormElement.h"
+#include "mozilla/dom/HTMLInputElement.h"
+#include "mozilla/dom/HTMLTextAreaElement.h"
+#include "mozilla/dom/IPCBlob.h"
+#include "mozilla/dom/IPCBlobUtils.h"
+#include "mozilla/dom/MessageBroadcaster.h"
+#include "mozilla/dom/MessageListenerManager.h"
+#include "mozilla/dom/MessagePort.h"
+#include "mozilla/dom/MouseEventBinding.h"
+#include "mozilla/dom/NameSpaceConstants.h"
+#include "mozilla/dom/NodeBinding.h"
+#include "mozilla/dom/NodeInfo.h"
+#include "mozilla/dom/PBrowser.h"
+#include "mozilla/dom/PContentChild.h"
+#include "mozilla/dom/PrototypeList.h"
+#include "mozilla/dom/ReferrerPolicyBinding.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/Selection.h"
+#include "mozilla/dom/ShadowRoot.h"
+#include "mozilla/dom/Text.h"
+#include "mozilla/dom/UserActivation.h"
+#include "mozilla/dom/WindowContext.h"
+#include "mozilla/dom/WorkerCommon.h"
+#include "mozilla/dom/WorkerPrivate.h"
+#include "mozilla/dom/WorkerRunnable.h"
+#include "mozilla/dom/XULCommandEvent.h"
+#include "mozilla/fallible.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/BaseMargin.h"
+#include "mozilla/gfx/BasePoint.h"
+#include "mozilla/gfx/BaseSize.h"
+#include "mozilla/gfx/DataSurfaceHelpers.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/gfx/Rect.h"
+#include "mozilla/gfx/Types.h"
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/ipc/SharedMemory.h"
+#include "mozilla/net/UrlClassifierCommon.h"
+#include "mozilla/widget/IMEData.h"
+#include "nsAboutProtocolUtils.h"
+#include "nsAlgorithm.h"
+#include "nsArrayUtils.h"
+#include "nsAtom.h"
+#include "nsAttrName.h"
+#include "nsAttrValue.h"
+#include "nsAttrValueInlines.h"
+#include "nsBaseHashtable.h"
+#include "nsCCUncollectableMarker.h"
+#include "nsCOMPtr.h"
+#include "nsCRT.h"
+#include "nsCRTGlue.h"
+#include "nsCanvasFrame.h"
+#include "nsCaseTreatment.h"
+#include "nsCharSeparatedTokenizer.h"
+#include "nsCharTraits.h"
+#include "nsCompatibility.h"
+#include "nsComponentManagerUtils.h"
+#include "nsContainerFrame.h"
+#include "nsContentCreatorFunctions.h"
+#include "nsContentDLF.h"
+#include "nsContentList.h"
+#include "nsContentListDeclarations.h"
+#include "nsContentPolicyUtils.h"
+#include "nsCoord.h"
+#include "nsCycleCollectionNoteChild.h"
+#include "nsDOMMutationObserver.h"
+#include "nsDOMString.h"
+#include "nsTHashMap.h"
+#include "nsDebug.h"
+#include "nsDocShell.h"
+#include "nsDocShellCID.h"
+#include "nsError.h"
+#include "nsFocusManager.h"
+#include "nsFrameList.h"
+#include "nsFrameLoader.h"
+#include "nsFrameLoaderOwner.h"
+#include "nsGenericHTMLElement.h"
+#include "nsGkAtoms.h"
+#include "nsGlobalWindowInner.h"
+#include "nsGlobalWindowOuter.h"
+#include "nsHTMLDocument.h"
+#include "nsHTMLTags.h"
+#include "nsHashKeys.h"
+#include "nsHtml5StringParser.h"
+#include "nsIAboutModule.h"
+#include "nsIAnonymousContentCreator.h"
+#include "nsIAppShell.h"
+#include "nsIArray.h"
+#include "nsIAsyncVerifyRedirectCallback.h"
+#include "nsIBidiKeyboard.h"
+#include "nsIBrowser.h"
+#include "nsICacheInfoChannel.h"
+#include "nsICategoryManager.h"
+#include "nsIChannel.h"
+#include "nsIChannelEventSink.h"
+#include "nsIClassifiedChannel.h"
+#include "nsIConsoleService.h"
+#include "nsIContent.h"
+#include "nsIContentInlines.h"
+#include "nsIContentPolicy.h"
+#include "nsIContentSecurityPolicy.h"
+#include "nsIContentSink.h"
+#include "nsIContentViewer.h"
+#include "nsIDOMWindowUtils.h"
+#include "nsIDocShell.h"
+#include "nsIDocShellTreeItem.h"
+#include "nsIDocumentEncoder.h"
+#include "nsIDocumentLoaderFactory.h"
+#include "nsIDragService.h"
+#include "nsIDragSession.h"
+#include "nsIFile.h"
+#include "nsIFocusManager.h"
+#include "nsIFormControl.h"
+#include "nsIFragmentContentSink.h"
+#include "nsIFrame.h"
+#include "nsIGlobalObject.h"
+#include "nsIHttpChannel.h"
+#include "nsIHttpChannelInternal.h"
+#include "nsIIOService.h"
+#include "nsIImageLoadingContent.h"
+#include "nsIInputStream.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsILoadContext.h"
+#include "nsILoadGroup.h"
+#include "nsILoadInfo.h"
+#include "nsIMIMEService.h"
+#include "nsIMemoryReporter.h"
+#include "nsINetUtil.h"
+#include "nsINode.h"
+#include "nsIObjectLoadingContent.h"
+#include "nsIObserver.h"
+#include "nsIObserverService.h"
+#include "nsIParserUtils.h"
+#include "nsIPermissionManager.h"
+#include "nsIPluginTag.h"
+#include "nsIPrincipal.h"
+#include "nsIProperties.h"
+#include "nsIProtocolHandler.h"
+#include "nsIRequest.h"
+#include "nsIRunnable.h"
+#include "nsIScreen.h"
+#include "nsIScriptError.h"
+#include "nsIScriptGlobalObject.h"
+#include "nsIScriptObjectPrincipal.h"
+#include "nsIScriptSecurityManager.h"
+#include "nsISerialEventTarget.h"
+#include "nsIStreamConverter.h"
+#include "nsIStreamConverterService.h"
+#include "nsIStringBundle.h"
+#include "nsISupports.h"
+#include "nsISupportsPrimitives.h"
+#include "nsISupportsUtils.h"
+#include "nsITransferable.h"
+#include "nsIURI.h"
+#include "nsIURIMutator.h"
+#if defined(MOZ_THUNDERBIRD) || defined(MOZ_SUITE)
+#  include "nsIURIWithSpecialOrigin.h"
+#endif
+#include "nsIUserIdleServiceInternal.h"
+#include "nsIWeakReferenceUtils.h"
+#include "nsIWebNavigation.h"
+#include "nsIWebNavigationInfo.h"
+#include "nsIWidget.h"
+#include "nsIWindowMediator.h"
+#include "nsIXPConnect.h"
+#include "nsJSPrincipals.h"
+#include "nsJSUtils.h"
+#include "nsLayoutUtils.h"
+#include "nsLiteralString.h"
+#include "nsMappedAttributes.h"
+#include "nsMargin.h"
+#include "nsMimeTypes.h"
+#include "nsNameSpaceManager.h"
+#include "nsNetCID.h"
+#include "nsNetUtil.h"
+#include "nsNodeInfoManager.h"
+#include "nsPIDOMWindow.h"
+#include "nsPIDOMWindowInlines.h"
+#include "nsParser.h"
+#include "nsParserConstants.h"
+#include "nsPluginHost.h"
+#include "nsPoint.h"
+#include "nsPointerHashKeys.h"
+#include "nsPresContext.h"
+#include "nsQueryFrame.h"
+#include "nsQueryObject.h"
+#include "nsRange.h"
+#include "nsRefPtrHashtable.h"
+#include "nsSandboxFlags.h"
+#include "nsScriptSecurityManager.h"
+#include "nsServiceManagerUtils.h"
+#include "nsStreamUtils.h"
+#include "nsString.h"
+#include "nsStringBuffer.h"
+#include "nsStringBundle.h"
+#include "nsStringFlags.h"
+#include "nsStringFwd.h"
+#include "nsStringIterator.h"
+#include "nsStringStream.h"
+#include "nsTArray.h"
+#include "nsTLiteralString.h"
+#include "nsTPromiseFlatString.h"
+#include "nsTStringRepr.h"
+#include "nsTextFragment.h"
+#include "nsTextNode.h"
+#include "nsThreadManager.h"
+#include "nsThreadUtils.h"
+#include "nsTreeSanitizer.h"
+#include "nsUGenCategory.h"
+#include "nsURLHelper.h"
+#include "nsUnicodeProperties.h"
+#include "nsVariant.h"
+#include "nsWidgetsCID.h"
+#include "nsView.h"
+#include "nsViewManager.h"
+#include "nsXPCOM.h"
+#include "nsXPCOMCID.h"
+#include "nsXULAppAPI.h"
+#include "nsXULElement.h"
+#include "nsXULPopupManager.h"
+#include "nscore.h"
+#include "prinrval.h"
+#include "xpcprivate.h"
+#include "xpcpublic.h"
+
+#if defined(XP_WIN)
+// Undefine LoadImage to prevent naming conflict with Windows.
+#  undef LoadImage
+#endif
+
+extern "C" int MOZ_XMLTranslateEntity(const char* ptr, const char* end,
+                                      const char** next, char16_t* result);
+extern "C" int MOZ_XMLCheckQName(const char* ptr, const char* end, int ns_aware,
+                                 const char** colon);
+
+using namespace mozilla::dom;
+using namespace mozilla::ipc;
+using namespace mozilla::gfx;
+using namespace mozilla::layers;
+using namespace mozilla::widget;
+using namespace mozilla;
+
+const char kLoadAsData[] = "loadAsData";
+
+nsIXPConnect* nsContentUtils::sXPConnect;
+nsIScriptSecurityManager* nsContentUtils::sSecurityManager;
+nsIPrincipal* nsContentUtils::sSystemPrincipal;
+nsIPrincipal* nsContentUtils::sNullSubjectPrincipal;
+nsIConsoleService* nsContentUtils::sConsoleService;
+nsTHashMap<nsRefPtrHashKey<nsAtom>, EventNameMapping>*
+    nsContentUtils::sAtomEventTable = nullptr;
+nsTHashMap<nsStringHashKey, EventNameMapping>*
+    nsContentUtils::sStringEventTable = nullptr;
+nsTArray<RefPtr<nsAtom>>* nsContentUtils::sUserDefinedEvents = nullptr;
+nsIStringBundleService* nsContentUtils::sStringBundleService;
+
+static StaticRefPtr<nsIStringBundle>
+    sStringBundles[nsContentUtils::PropertiesFile_COUNT];
+
+nsIContentPolicy* nsContentUtils::sContentPolicyService;
+bool nsContentUtils::sTriedToGetContentPolicy = false;
+StaticRefPtr<nsIBidiKeyboard> nsContentUtils::sBidiKeyboard;
+uint32_t nsContentUtils::sScriptBlockerCount = 0;
+uint32_t nsContentUtils::sDOMNodeRemovedSuppressCount = 0;
+AutoTArray<nsCOMPtr<nsIRunnable>, 8>* nsContentUtils::sBlockedScriptRunners =
+    nullptr;
+uint32_t nsContentUtils::sRunnersCountAtFirstBlocker = 0;
+nsIInterfaceRequestor* nsContentUtils::sSameOriginChecker = nullptr;
+
+bool nsContentUtils::sIsHandlingKeyBoardEvent = false;
+
+nsString* nsContentUtils::sShiftText = nullptr;
+nsString* nsContentUtils::sControlText = nullptr;
+nsString* nsContentUtils::sMetaText = nullptr;
+nsString* nsContentUtils::sOSText = nullptr;
+nsString* nsContentUtils::sAltText = nullptr;
+nsString* nsContentUtils::sModifierSeparator = nullptr;
+
+bool nsContentUtils::sInitialized = false;
+#ifndef RELEASE_OR_BETA
+bool nsContentUtils::sBypassCSSOMOriginCheck = false;
+#endif
+
+nsCString* nsContentUtils::sJSScriptBytecodeMimeType = nullptr;
+nsCString* nsContentUtils::sJSModuleBytecodeMimeType = nullptr;
+
+nsContentUtils::UserInteractionObserver*
+    nsContentUtils::sUserInteractionObserver = nullptr;
+
+nsHtml5StringParser* nsContentUtils::sHTMLFragmentParser = nullptr;
+nsParser* nsContentUtils::sXMLFragmentParser = nullptr;
+nsIFragmentContentSink* nsContentUtils::sXMLFragmentSink = nullptr;
+bool nsContentUtils::sFragmentParsingActive = false;
+
+bool nsContentUtils::sMayHaveFormCheckboxStateChangeListeners = false;
+bool nsContentUtils::sMayHaveFormRadioStateChangeListeners = false;
+
+mozilla::LazyLogModule nsContentUtils::gResistFingerprintingLog(
+    "nsResistFingerprinting");
+mozilla::LazyLogModule nsContentUtils::sDOMDumpLog("Dump");
+
+int32_t nsContentUtils::sInnerOrOuterWindowCount = 0;
+uint32_t nsContentUtils::sInnerOrOuterWindowSerialCounter = 0;
+
+template Maybe<int32_t> nsContentUtils::ComparePoints(
+    const RangeBoundary& aFirstBoundary, const RangeBoundary& aSecondBoundary);
+template Maybe<int32_t> nsContentUtils::ComparePoints(
+    const RangeBoundary& aFirstBoundary,
+    const RawRangeBoundary& aSecondBoundary);
+template Maybe<int32_t> nsContentUtils::ComparePoints(
+    const RawRangeBoundary& aFirstBoundary,
+    const RangeBoundary& aSecondBoundary);
+template Maybe<int32_t> nsContentUtils::ComparePoints(
+    const RawRangeBoundary& aFirstBoundary,
+    const RawRangeBoundary& aSecondBoundary);
+
+template int32_t nsContentUtils::ComparePoints_Deprecated(
+    const RangeBoundary& aFirstBoundary, const RangeBoundary& aSecondBoundary,
+    bool* aDisconnected);
+template int32_t nsContentUtils::ComparePoints_Deprecated(
+    const RangeBoundary& aFirstBoundary,
+    const RawRangeBoundary& aSecondBoundary, bool* aDisconnected);
+template int32_t nsContentUtils::ComparePoints_Deprecated(
+    const RawRangeBoundary& aFirstBoundary,
+    const RangeBoundary& aSecondBoundary, bool* aDisconnected);
+template int32_t nsContentUtils::ComparePoints_Deprecated(
+    const RawRangeBoundary& aFirstBoundary,
+    const RawRangeBoundary& aSecondBoundary, bool* aDisconnected);
+
+// Subset of
+// http://www.whatwg.org/specs/web-apps/current-work/#autofill-field-name
+enum AutocompleteUnsupportedFieldName : uint8_t {
+#define AUTOCOMPLETE_UNSUPPORTED_FIELD_NAME(name_, value_) \
+  eAutocompleteUnsupportedFieldName_##name_,
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_UNSUPPORTED_FIELD_NAME
+};
+
+enum AutocompleteNoPersistFieldName : uint8_t {
+#define AUTOCOMPLETE_NO_PERSIST_FIELD_NAME(name_, value_) \
+  eAutocompleteNoPersistFieldName_##name_,
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_NO_PERSIST_FIELD_NAME
+};
+
+enum AutocompleteUnsupportFieldContactHint : uint8_t {
+#define AUTOCOMPLETE_UNSUPPORTED_FIELD_CONTACT_HINT(name_, value_) \
+  eAutocompleteUnsupportedFieldContactHint_##name_,
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_UNSUPPORTED_FIELD_CONTACT_HINT
+};
+
+enum AutocompleteFieldName : uint8_t {
+#define AUTOCOMPLETE_FIELD_NAME(name_, value_) eAutocompleteFieldName_##name_,
+#define AUTOCOMPLETE_CONTACT_FIELD_NAME(name_, value_) \
+  AUTOCOMPLETE_FIELD_NAME(name_, value_)
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_FIELD_NAME
+#undef AUTOCOMPLETE_CONTACT_FIELD_NAME
+};
+
+enum AutocompleteFieldHint : uint8_t {
+#define AUTOCOMPLETE_FIELD_HINT(name_, value_) eAutocompleteFieldHint_##name_,
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_FIELD_HINT
+};
+
+enum AutocompleteFieldContactHint : uint8_t {
+#define AUTOCOMPLETE_FIELD_CONTACT_HINT(name_, value_) \
+  eAutocompleteFieldContactHint_##name_,
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_FIELD_CONTACT_HINT
+};
+
+enum AutocompleteCategory {
+#define AUTOCOMPLETE_CATEGORY(name_, value_) eAutocompleteCategory_##name_,
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_CATEGORY
+};
+
+static const nsAttrValue::EnumTable kAutocompleteUnsupportedFieldNameTable[] = {
+#define AUTOCOMPLETE_UNSUPPORTED_FIELD_NAME(name_, value_) \
+  {value_, eAutocompleteUnsupportedFieldName_##name_},
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_UNSUPPORTED_FIELD_NAME
+    {nullptr, 0}};
+
+static const nsAttrValue::EnumTable kAutocompleteNoPersistFieldNameTable[] = {
+#define AUTOCOMPLETE_NO_PERSIST_FIELD_NAME(name_, value_) \
+  {value_, eAutocompleteNoPersistFieldName_##name_},
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_NO_PERSIST_FIELD_NAME
+    {nullptr, 0}};
+
+static const nsAttrValue::EnumTable
+    kAutocompleteUnsupportedContactFieldHintTable[] = {
+#define AUTOCOMPLETE_UNSUPPORTED_FIELD_CONTACT_HINT(name_, value_) \
+  {value_, eAutocompleteUnsupportedFieldContactHint_##name_},
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_UNSUPPORTED_FIELD_CONTACT_HINT
+        {nullptr, 0}};
+
+static const nsAttrValue::EnumTable kAutocompleteFieldNameTable[] = {
+#define AUTOCOMPLETE_FIELD_NAME(name_, value_) \
+  {value_, eAutocompleteFieldName_##name_},
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_FIELD_NAME
+    {nullptr, 0}};
+
+static const nsAttrValue::EnumTable kAutocompleteContactFieldNameTable[] = {
+#define AUTOCOMPLETE_CONTACT_FIELD_NAME(name_, value_) \
+  {value_, eAutocompleteFieldName_##name_},
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_CONTACT_FIELD_NAME
+    {nullptr, 0}};
+
+static const nsAttrValue::EnumTable kAutocompleteFieldHintTable[] = {
+#define AUTOCOMPLETE_FIELD_HINT(name_, value_) \
+  {value_, eAutocompleteFieldHint_##name_},
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_FIELD_HINT
+    {nullptr, 0}};
+
+static const nsAttrValue::EnumTable kAutocompleteContactFieldHintTable[] = {
+#define AUTOCOMPLETE_FIELD_CONTACT_HINT(name_, value_) \
+  {value_, eAutocompleteFieldContactHint_##name_},
+#include "AutocompleteFieldList.h"
+#undef AUTOCOMPLETE_FIELD_CONTACT_HINT
+    {nullptr, 0}};
+
+namespace {
+
+static PLDHashTable* sEventListenerManagersHash;
+
+// A global hashtable to for keeping the arena alive for cross docGroup node
+// adoption.
+static nsRefPtrHashtable<nsPtrHashKey<const nsINode>, mozilla::dom::DOMArena>*
+    sDOMArenaHashtable;
+
+class DOMEventListenerManagersHashReporter final : public nsIMemoryReporter {
+  MOZ_DEFINE_MALLOC_SIZE_OF(MallocSizeOf)
+
+  ~DOMEventListenerManagersHashReporter() = default;
+
+ public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override {
+    // We don't measure the |EventListenerManager| objects pointed to by the
+    // entries because those references are non-owning.
+    int64_t amount =
+        sEventListenerManagersHash
+            ? sEventListenerManagersHash->ShallowSizeOfIncludingThis(
+                  MallocSizeOf)
+            : 0;
+
+    MOZ_COLLECT_REPORT(
+        "explicit/dom/event-listener-managers-hash", KIND_HEAP, UNITS_BYTES,
+        amount, "Memory used by the event listener manager's hash table.");
+
+    return NS_OK;
+  }
+};
+
+NS_IMPL_ISUPPORTS(DOMEventListenerManagersHashReporter, nsIMemoryReporter)
+
+class EventListenerManagerMapEntry : public PLDHashEntryHdr {
+ public:
+  explicit EventListenerManagerMapEntry(const void* aKey) : mKey(aKey) {}
+
+  ~EventListenerManagerMapEntry() {
+    NS_ASSERTION(!mListenerManager, "caller must release and disconnect ELM");
+  }
+
+ protected:          // declared protected to silence clang warnings
+  const void* mKey;  // must be first, to look like PLDHashEntryStub
+
+ public:
+  RefPtr<EventListenerManager> mListenerManager;
+};
+
+static void EventListenerManagerHashInitEntry(PLDHashEntryHdr* entry,
+                                              const void* key) {
+  // Initialize the entry with placement new
+  new (entry) EventListenerManagerMapEntry(key);
+}
+
+static void EventListenerManagerHashClearEntry(PLDHashTable* table,
+                                               PLDHashEntryHdr* entry) {
+  EventListenerManagerMapEntry* lm =
+      static_cast<EventListenerManagerMapEntry*>(entry);
+
+  // Let the EventListenerManagerMapEntry clean itself up...
+  lm->~EventListenerManagerMapEntry();
+}
+
+class SameOriginCheckerImpl final : public nsIChannelEventSink,
+                                    public nsIInterfaceRequestor {
+  ~SameOriginCheckerImpl() = default;
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSICHANNELEVENTSINK
+  NS_DECL_NSIINTERFACEREQUESTOR
+};
+
+}  // namespace
+
+void AutoSuppressEventHandling::SuppressDocument(Document* aDoc) {
+  // Note: Document::SuppressEventHandling will also automatically suppress
+  // event handling for any in-process sub-documents. However, since we need
+  // to deal with cases where remote BrowsingContexts may be interleaved
+  // with in-process ones, we still need to walk the entire tree ourselves.
+  // This may be slightly redundant in some cases, but since event handling
+  // suppressions maintain a count of current blockers, it does not cause
+  // any problems.
+  aDoc->SuppressEventHandling();
+}
+
+void AutoSuppressEventHandling::UnsuppressDocument(Document* aDoc) {
+  aDoc->UnsuppressEventHandlingAndFireEvents(true);
+}
+
+AutoSuppressEventHandling::~AutoSuppressEventHandling() {
+  UnsuppressDocuments();
+}
+
+void AutoSuppressEventHandlingAndSuspend::SuppressDocument(Document* aDoc) {
+  AutoSuppressEventHandling::SuppressDocument(aDoc);
+  if (nsCOMPtr<nsPIDOMWindowInner> win = aDoc->GetInnerWindow()) {
+    win->Suspend();
+    mWindows.AppendElement(win);
+  }
+}
+
+AutoSuppressEventHandlingAndSuspend::~AutoSuppressEventHandlingAndSuspend() {
+  for (const auto& win : mWindows) {
+    win->Resume();
+  }
+}
+
+/**
+ * This class is used to determine whether or not the user is currently
+ * interacting with the browser. It listens to observer events to toggle the
+ * value of the sUserActive static.
+ *
+ * This class is an internal implementation detail.
+ * nsContentUtils::GetUserIsInteracting() should be used to access current
+ * user interaction status.
+ */
+class nsContentUtils::UserInteractionObserver final
+    : public nsIObserver,
+      public BackgroundHangAnnotator {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  void Init();
+  void Shutdown();
+  void AnnotateHang(BackgroundHangAnnotations& aAnnotations) override;
+
+  static Atomic<bool> sUserActive;
+
+ private:
+  ~UserInteractionObserver() = default;
+};
+
+static constexpr nsLiteralCString kRfpPrefs[] = {
+    "privacy.resistFingerprinting"_ns,
+    "privacy.resistFingerprinting.pbmode"_ns,
+    "privacy.fingerprintingProtection"_ns,
+    "privacy.fingerprintingProtection.pbmode"_ns,
+    "privacy.fingerprintingProtection.overrides"_ns,
+};
+
+static void RecomputeResistFingerprintingAllDocs(const char*, void*) {
+  AutoTArray<RefPtr<BrowsingContextGroup>, 5> bcGroups;
+  BrowsingContextGroup::GetAllGroups(bcGroups);
+  for (auto& bcGroup : bcGroups) {
+    AutoTArray<DocGroup*, 5> docGroups;
+    bcGroup->GetDocGroups(docGroups);
+    for (auto* docGroup : docGroups) {
+      for (Document* doc : *docGroup) {
+        if (doc->RecomputeResistFingerprinting()) {
+          if (auto* pc = doc->GetPresContext()) {
+            pc->MediaFeatureValuesChanged(
+                {MediaFeatureChangeReason::PreferenceChange},
+                MediaFeatureChangePropagation::JustThisDocument);
+          }
+        }
+      }
+    }
+  }
+}
+
+// static
+nsresult nsContentUtils::Init() {
+  if (sInitialized) {
+    NS_WARNING("Init() called twice");
+
+    return NS_OK;
+  }
+
+  nsHTMLTags::AddRefTable();
+
+  sXPConnect = nsXPConnect::XPConnect();
+  // We hold a strong ref to sXPConnect to ensure that it does not go away until
+  // nsLayoutStatics::Shutdown is happening.  Otherwise ~nsXPConnect can be
+  // triggered by xpcModuleDtor late in shutdown and cause crashes due to
+  // various stuff already being torn down by then.  Note that this means that
+  // we are effectively making sure that if we leak nsLayoutStatics then we also
+  // leak nsXPConnect.
+  NS_ADDREF(sXPConnect);
+
+  sSecurityManager = nsScriptSecurityManager::GetScriptSecurityManager();
+  if (!sSecurityManager) return NS_ERROR_FAILURE;
+  NS_ADDREF(sSecurityManager);
+
+  sSecurityManager->GetSystemPrincipal(&sSystemPrincipal);
+  MOZ_ASSERT(sSystemPrincipal);
+
+  RefPtr<NullPrincipal> nullPrincipal =
+      NullPrincipal::CreateWithoutOriginAttributes();
+  if (!nullPrincipal) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nullPrincipal.forget(&sNullSubjectPrincipal);
+
+  if (!InitializeEventTable()) return NS_ERROR_FAILURE;
+
+  if (!sEventListenerManagersHash) {
+    static const PLDHashTableOps hash_table_ops = {
+        PLDHashTable::HashVoidPtrKeyStub, PLDHashTable::MatchEntryStub,
+        PLDHashTable::MoveEntryStub, EventListenerManagerHashClearEntry,
+        EventListenerManagerHashInitEntry};
+
+    sEventListenerManagersHash =
+        new PLDHashTable(&hash_table_ops, sizeof(EventListenerManagerMapEntry));
+
+    RegisterStrongMemoryReporter(new DOMEventListenerManagersHashReporter());
+  }
+
+  sBlockedScriptRunners = new AutoTArray<nsCOMPtr<nsIRunnable>, 8>;
+
+#ifndef RELEASE_OR_BETA
+  sBypassCSSOMOriginCheck = getenv("MOZ_BYPASS_CSSOM_ORIGIN_CHECK");
+#endif
+
+  Element::InitCCCallbacks();
+
+  Unused << nsRFPService::GetOrCreate();
+
+  if (XRE_IsParentProcess()) {
+    AsyncPrecreateStringBundles();
+  }
+
+  RefPtr<UserInteractionObserver> uio = new UserInteractionObserver();
+  uio->Init();
+  uio.forget(&sUserInteractionObserver);
+
+  for (const auto& pref : kRfpPrefs) {
+    Preferences::RegisterCallback(RecomputeResistFingerprintingAllDocs, pref);
+  }
+
+  sInitialized = true;
+
+  return NS_OK;
+}
+
+bool nsContentUtils::InitJSBytecodeMimeType() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!sJSScriptBytecodeMimeType);
+  MOZ_ASSERT(!sJSModuleBytecodeMimeType);
+
+  JS::BuildIdCharVector jsBuildId;
+  if (!JS::GetScriptTranscodingBuildId(&jsBuildId)) {
+    return false;
+  }
+
+  nsDependentCSubstring jsBuildIdStr(jsBuildId.begin(), jsBuildId.length());
+  sJSScriptBytecodeMimeType =
+      new nsCString("javascript/moz-script-bytecode-"_ns + jsBuildIdStr);
+  sJSModuleBytecodeMimeType =
+      new nsCString("javascript/moz-module-bytecode-"_ns + jsBuildIdStr);
+  return true;
+}
+
+void nsContentUtils::GetShiftText(nsAString& text) {
+  if (!sShiftText) InitializeModifierStrings();
+  text.Assign(*sShiftText);
+}
+
+void nsContentUtils::GetControlText(nsAString& text) {
+  if (!sControlText) InitializeModifierStrings();
+  text.Assign(*sControlText);
+}
+
+void nsContentUtils::GetMetaText(nsAString& text) {
+  if (!sMetaText) InitializeModifierStrings();
+  text.Assign(*sMetaText);
+}
+
+void nsContentUtils::GetOSText(nsAString& text) {
+  if (!sOSText) {
+    InitializeModifierStrings();
+  }
+  text.Assign(*sOSText);
+}
+
+void nsContentUtils::GetAltText(nsAString& text) {
+  if (!sAltText) InitializeModifierStrings();
+  text.Assign(*sAltText);
+}
+
+void nsContentUtils::GetModifierSeparatorText(nsAString& text) {
+  if (!sModifierSeparator) InitializeModifierStrings();
+  text.Assign(*sModifierSeparator);
+}
+
+void nsContentUtils::InitializeModifierStrings() {
+  // load the display strings for the keyboard accelerators
+  nsCOMPtr<nsIStringBundleService> bundleService =
+      mozilla::components::StringBundle::Service();
+  nsCOMPtr<nsIStringBundle> bundle;
+  DebugOnly<nsresult> rv = NS_OK;
+  if (bundleService) {
+    rv = bundleService->CreateBundle(
+        "chrome://global-platform/locale/platformKeys.properties",
+        getter_AddRefs(bundle));
+  }
+
+  NS_ASSERTION(
+      NS_SUCCEEDED(rv) && bundle,
+      "chrome://global/locale/platformKeys.properties could not be loaded");
+  nsAutoString shiftModifier;
+  nsAutoString metaModifier;
+  nsAutoString osModifier;
+  nsAutoString altModifier;
+  nsAutoString controlModifier;
+  nsAutoString modifierSeparator;
+  if (bundle) {
+    // macs use symbols for each modifier key, so fetch each from the bundle,
+    // which also covers i18n
+    bundle->GetStringFromName("VK_SHIFT", shiftModifier);
+    bundle->GetStringFromName("VK_META", metaModifier);
+    bundle->GetStringFromName("VK_WIN", osModifier);
+    bundle->GetStringFromName("VK_ALT", altModifier);
+    bundle->GetStringFromName("VK_CONTROL", controlModifier);
+    bundle->GetStringFromName("MODIFIER_SEPARATOR", modifierSeparator);
+  }
+  // if any of these don't exist, we get  an empty string
+  sShiftText = new nsString(shiftModifier);
+  sMetaText = new nsString(metaModifier);
+  sOSText = new nsString(osModifier);
+  sAltText = new nsString(altModifier);
+  sControlText = new nsString(controlModifier);
+  sModifierSeparator = new nsString(modifierSeparator);
+}
+
+mozilla::EventClassID nsContentUtils::GetEventClassIDFromMessage(
+    EventMessage aEventMessage) {
+  switch (aEventMessage) {
+#define MESSAGE_TO_EVENT(name_, message_, type_, struct_) \
+  case message_:                                          \
+    return struct_;
+#include "mozilla/EventNameList.h"
+#undef MESSAGE_TO_EVENT
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid event message?");
+      return eBasicEventClass;
+  }
+}
+
+bool nsContentUtils::IsExternalProtocol(nsIURI* aURI) {
+  bool doesNotReturnData = false;
+  nsresult rv = NS_URIChainHasFlags(
+      aURI, nsIProtocolHandler::URI_DOES_NOT_RETURN_DATA, &doesNotReturnData);
+  return NS_SUCCEEDED(rv) && doesNotReturnData;
+}
+
+static nsAtom* GetEventTypeFromMessage(EventMessage aEventMessage) {
+  switch (aEventMessage) {
+#define MESSAGE_TO_EVENT(name_, message_, type_, struct_) \
+  case message_:                                          \
+    return nsGkAtoms::on##name_;
+#include "mozilla/EventNameList.h"
+#undef MESSAGE_TO_EVENT
+    default:
+      return nullptr;
+  }
+}
+
+// Because of SVG/SMIL we have several atoms mapped to the same
+// id, but we can rely on MESSAGE_TO_EVENT to map id to only one atom.
+static bool ShouldAddEventToStringEventTable(const EventNameMapping& aMapping) {
+  MOZ_ASSERT(aMapping.mAtom);
+  return GetEventTypeFromMessage(aMapping.mMessage) == aMapping.mAtom;
+}
+
+bool nsContentUtils::InitializeEventTable() {
+  NS_ASSERTION(!sAtomEventTable, "EventTable already initialized!");
+  NS_ASSERTION(!sStringEventTable, "EventTable already initialized!");
+
+  static const EventNameMapping eventArray[] = {
+#define EVENT(name_, _message, _type, _class) \
+  {nsGkAtoms::on##name_, _type, _message, _class, false},
+#define WINDOW_ONLY_EVENT EVENT
+#define DOCUMENT_ONLY_EVENT EVENT
+#define NON_IDL_EVENT EVENT
+#include "mozilla/EventNameList.h"
+#undef WINDOW_ONLY_EVENT
+#undef NON_IDL_EVENT
+#undef EVENT
+      {nullptr}};
+
+  sAtomEventTable = new nsTHashMap<nsRefPtrHashKey<nsAtom>, EventNameMapping>(
+      ArrayLength(eventArray));
+  sStringEventTable = new nsTHashMap<nsStringHashKey, EventNameMapping>(
+      ArrayLength(eventArray));
+  sUserDefinedEvents = new nsTArray<RefPtr<nsAtom>>(64);
+
+  // Subtract one from the length because of the trailing null
+  for (uint32_t i = 0; i < ArrayLength(eventArray) - 1; ++i) {
+    MOZ_ASSERT(!sAtomEventTable->Contains(eventArray[i].mAtom),
+               "Double-defining event name; fix your EventNameList.h");
+    sAtomEventTable->InsertOrUpdate(eventArray[i].mAtom, eventArray[i]);
+    if (ShouldAddEventToStringEventTable(eventArray[i])) {
+      sStringEventTable->InsertOrUpdate(
+          Substring(nsDependentAtomString(eventArray[i].mAtom), 2),
+          eventArray[i]);
+    }
+  }
+
+  return true;
+}
+
+void nsContentUtils::InitializeTouchEventTable() {
+  static bool sEventTableInitialized = false;
+  if (!sEventTableInitialized && sAtomEventTable && sStringEventTable) {
+    sEventTableInitialized = true;
+    static const EventNameMapping touchEventArray[] = {
+#define EVENT(name_, _message, _type, _class)
+#define TOUCH_EVENT(name_, _message, _type, _class) \
+  {nsGkAtoms::on##name_, _type, _message, _class},
+#include "mozilla/EventNameList.h"
+#undef TOUCH_EVENT
+#undef EVENT
+        {nullptr}};
+    // Subtract one from the length because of the trailing null
+    for (uint32_t i = 0; i < ArrayLength(touchEventArray) - 1; ++i) {
+      sAtomEventTable->InsertOrUpdate(touchEventArray[i].mAtom,
+                                      touchEventArray[i]);
+      sStringEventTable->InsertOrUpdate(
+          Substring(nsDependentAtomString(touchEventArray[i].mAtom), 2),
+          touchEventArray[i]);
+    }
+  }
+}
+
+static bool Is8bit(const nsAString& aString) {
+  static const char16_t EIGHT_BIT = char16_t(~0x00FF);
+
+  for (nsAString::const_char_iterator start = aString.BeginReading(),
+                                      end = aString.EndReading();
+       start != end; ++start) {
+    if (*start & EIGHT_BIT) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+nsresult nsContentUtils::Btoa(const nsAString& aBinaryData,
+                              nsAString& aAsciiBase64String) {
+  if (!Is8bit(aBinaryData)) {
+    aAsciiBase64String.Truncate();
+    return NS_ERROR_DOM_INVALID_CHARACTER_ERR;
+  }
+
+  return Base64Encode(aBinaryData, aAsciiBase64String);
+}
+
+nsresult nsContentUtils::Atob(const nsAString& aAsciiBase64String,
+                              nsAString& aBinaryData) {
+  if (!Is8bit(aAsciiBase64String)) {
+    aBinaryData.Truncate();
+    return NS_ERROR_DOM_INVALID_CHARACTER_ERR;
+  }
+
+  const char16_t* start = aAsciiBase64String.BeginReading();
+  const char16_t* cur = start;
+  const char16_t* end = aAsciiBase64String.EndReading();
+  bool hasWhitespace = false;
+
+  while (cur < end) {
+    if (nsContentUtils::IsHTMLWhitespace(*cur)) {
+      hasWhitespace = true;
+      break;
+    }
+    cur++;
+  }
+
+  nsresult rv;
+
+  if (hasWhitespace) {
+    nsString trimmedString;
+
+    if (!trimmedString.SetCapacity(aAsciiBase64String.Length(), fallible)) {
+      return NS_ERROR_DOM_INVALID_CHARACTER_ERR;
+    }
+
+    trimmedString.Append(start, cur - start);
+
+    while (cur < end) {
+      if (!nsContentUtils::IsHTMLWhitespace(*cur)) {
+        trimmedString.Append(*cur);
+      }
+      cur++;
+    }
+    rv = Base64Decode(trimmedString, aBinaryData);
+  } else {
+    rv = Base64Decode(aAsciiBase64String, aBinaryData);
+  }
+
+  if (NS_FAILED(rv) && rv == NS_ERROR_INVALID_ARG) {
+    return NS_ERROR_DOM_INVALID_CHARACTER_ERR;
+  }
+  return rv;
+}
+
+bool nsContentUtils::IsAutocompleteEnabled(
+    mozilla::dom::HTMLInputElement* aInput) {
+  MOZ_ASSERT(aInput, "aInput should not be null!");
+
+  nsAutoString autocomplete;
+  aInput->GetAutocomplete(autocomplete);
+
+  if (autocomplete.IsEmpty()) {
+    auto* form = aInput->GetForm();
+    if (!form) {
+      return true;
+    }
+
+    form->GetAutocomplete(autocomplete);
+  }
+
+  return !autocomplete.EqualsLiteral("off");
+}
+
+nsContentUtils::AutocompleteAttrState
+nsContentUtils::SerializeAutocompleteAttribute(
+    const nsAttrValue* aAttr, nsAString& aResult,
+    AutocompleteAttrState aCachedState) {
+  if (!aAttr ||
+      aCachedState == nsContentUtils::eAutocompleteAttrState_Invalid) {
+    return aCachedState;
+  }
+
+  if (aCachedState == nsContentUtils::eAutocompleteAttrState_Valid) {
+    uint32_t atomCount = aAttr->GetAtomCount();
+    for (uint32_t i = 0; i < atomCount; i++) {
+      if (i != 0) {
+        aResult.Append(' ');
+      }
+      aResult.Append(nsDependentAtomString(aAttr->AtomAt(i)));
+    }
+    nsContentUtils::ASCIIToLower(aResult);
+    return aCachedState;
+  }
+
+  aResult.Truncate();
+
+  mozilla::dom::AutocompleteInfo info;
+  AutocompleteAttrState state =
+      InternalSerializeAutocompleteAttribute(aAttr, info);
+  if (state == eAutocompleteAttrState_Valid) {
+    // Concatenate the info fields.
+    aResult = info.mSection;
+
+    if (!info.mAddressType.IsEmpty()) {
+      if (!aResult.IsEmpty()) {
+        aResult += ' ';
+      }
+      aResult += info.mAddressType;
+    }
+
+    if (!info.mContactType.IsEmpty()) {
+      if (!aResult.IsEmpty()) {
+        aResult += ' ';
+      }
+      aResult += info.mContactType;
+    }
+
+    if (!info.mFieldName.IsEmpty()) {
+      if (!aResult.IsEmpty()) {
+        aResult += ' ';
+      }
+      aResult += info.mFieldName;
+    }
+  }
+
+  return state;
+}
+
+nsContentUtils::AutocompleteAttrState
+nsContentUtils::SerializeAutocompleteAttribute(
+    const nsAttrValue* aAttr, mozilla::dom::AutocompleteInfo& aInfo,
+    AutocompleteAttrState aCachedState, bool aGrantAllValidValue) {
+  if (!aAttr ||
+      aCachedState == nsContentUtils::eAutocompleteAttrState_Invalid) {
+    return aCachedState;
+  }
+
+  return InternalSerializeAutocompleteAttribute(aAttr, aInfo,
+                                                aGrantAllValidValue);
+}
+
+/**
+ * Helper to validate the @autocomplete tokens.
+ *
+ * @return {AutocompleteAttrState} The state of the attribute (invalid/valid).
+ */
+nsContentUtils::AutocompleteAttrState
+nsContentUtils::InternalSerializeAutocompleteAttribute(
+    const nsAttrValue* aAttrVal, mozilla::dom::AutocompleteInfo& aInfo,
+    bool aGrantAllValidValue) {
+  // No autocomplete attribute so we are done
+  if (!aAttrVal) {
+    return eAutocompleteAttrState_Invalid;
+  }
+
+  uint32_t numTokens = aAttrVal->GetAtomCount();
+  if (!numTokens) {
+    return eAutocompleteAttrState_Invalid;
+  }
+
+  uint32_t index = numTokens - 1;
+  nsString tokenString = nsDependentAtomString(aAttrVal->AtomAt(index));
+  AutocompleteCategory category;
+  nsAttrValue enumValue;
+
+  bool unsupported = false;
+  if (!aGrantAllValidValue) {
+    unsupported = enumValue.ParseEnumValue(
+        tokenString, kAutocompleteUnsupportedFieldNameTable, false);
+    if (unsupported) {
+      return eAutocompleteAttrState_Invalid;
+    }
+  }
+
+  nsAutoString str;
+  bool result =
+      enumValue.ParseEnumValue(tokenString, kAutocompleteFieldNameTable, false);
+  if (result) {
+    // Off/Automatic/Normal categories.
+    if (enumValue.Equals(u"off"_ns, eIgnoreCase) ||
+        enumValue.Equals(u"on"_ns, eIgnoreCase)) {
+      if (numTokens > 1) {
+        return eAutocompleteAttrState_Invalid;
+      }
+      enumValue.ToString(str);
+      ASCIIToLower(str);
+      aInfo.mFieldName.Assign(str);
+      aInfo.mCanAutomaticallyPersist =
+          !enumValue.Equals(u"off"_ns, eIgnoreCase);
+      return eAutocompleteAttrState_Valid;
+    }
+
+    // Only allow on/off if form autofill @autocomplete values aren't enabled
+    // and it doesn't grant all valid values.
+    if (!StaticPrefs::dom_forms_autocomplete_formautofill() &&
+        !aGrantAllValidValue) {
+      return eAutocompleteAttrState_Invalid;
+    }
+
+    // Normal category
+    if (numTokens > 3) {
+      return eAutocompleteAttrState_Invalid;
+    }
+    category = eAutocompleteCategory_NORMAL;
+  } else {  // Check if the last token is of the contact category instead.
+    // Only allow on/off if form autofill @autocomplete values aren't enabled
+    // and it doesn't grant all valid values.
+    if (!StaticPrefs::dom_forms_autocomplete_formautofill() &&
+        !aGrantAllValidValue) {
+      return eAutocompleteAttrState_Invalid;
+    }
+
+    result = enumValue.ParseEnumValue(
+        tokenString, kAutocompleteContactFieldNameTable, false);
+    if (!result || numTokens > 4) {
+      return eAutocompleteAttrState_Invalid;
+    }
+
+    category = eAutocompleteCategory_CONTACT;
+  }
+
+  enumValue.ToString(str);
+  ASCIIToLower(str);
+  aInfo.mFieldName.Assign(str);
+
+  aInfo.mCanAutomaticallyPersist = !enumValue.ParseEnumValue(
+      tokenString, kAutocompleteNoPersistFieldNameTable, false);
+
+  // We are done if this was the only token.
+  if (numTokens == 1) {
+    return eAutocompleteAttrState_Valid;
+  }
+
+  --index;
+  tokenString = nsDependentAtomString(aAttrVal->AtomAt(index));
+
+  if (category == eAutocompleteCategory_CONTACT) {
+    if (!aGrantAllValidValue) {
+      unsupported = enumValue.ParseEnumValue(
+          tokenString, kAutocompleteUnsupportedContactFieldHintTable, false);
+      if (unsupported) {
+        return eAutocompleteAttrState_Invalid;
+      }
+    }
+
+    nsAttrValue contactFieldHint;
+    result = contactFieldHint.ParseEnumValue(
+        tokenString, kAutocompleteContactFieldHintTable, false);
+    if (result) {
+      nsAutoString contactFieldHintString;
+      contactFieldHint.ToString(contactFieldHintString);
+      ASCIIToLower(contactFieldHintString);
+      aInfo.mContactType.Assign(contactFieldHintString);
+      if (index == 0) {
+        return eAutocompleteAttrState_Valid;
+      }
+      --index;
+      tokenString = nsDependentAtomString(aAttrVal->AtomAt(index));
+    }
+  }
+
+  // Check for billing/shipping tokens
+  nsAttrValue fieldHint;
+  if (fieldHint.ParseEnumValue(tokenString, kAutocompleteFieldHintTable,
+                               false)) {
+    nsString fieldHintString;
+    fieldHint.ToString(fieldHintString);
+    ASCIIToLower(fieldHintString);
+    aInfo.mAddressType.Assign(fieldHintString);
+    if (index == 0) {
+      return eAutocompleteAttrState_Valid;
+    }
+    --index;
+    tokenString = nsDependentAtomString(aAttrVal->AtomAt(index));
+  }
+
+  // Check for section-* token
+  const nsDependentSubstring& section = Substring(tokenString, 0, 8);
+  if (section.LowerCaseEqualsASCII("section-")) {
+    ASCIIToLower(tokenString);
+    aInfo.mSection.Assign(tokenString);
+    if (index == 0) {
+      return eAutocompleteAttrState_Valid;
+    }
+  }
+
+  // Clear the fields as the autocomplete attribute is invalid.
+  aInfo.mSection.Truncate();
+  aInfo.mAddressType.Truncate();
+  aInfo.mContactType.Truncate();
+  aInfo.mFieldName.Truncate();
+
+  return eAutocompleteAttrState_Invalid;
+}
+
+// Parse an integer according to HTML spec
+template <class CharT>
+int32_t nsContentUtils::ParseHTMLIntegerImpl(
+    const CharT* aStart, const CharT* aEnd,
+    ParseHTMLIntegerResultFlags* aResult) {
+  int result = eParseHTMLInteger_NoFlags;
+
+  const CharT* iter = aStart;
+
+  while (iter != aEnd && nsContentUtils::IsHTMLWhitespace(*iter)) {
+    result |= eParseHTMLInteger_NonStandard;
+    ++iter;
+  }
+
+  if (iter == aEnd) {
+    result |= eParseHTMLInteger_Error | eParseHTMLInteger_ErrorNoValue;
+    *aResult = (ParseHTMLIntegerResultFlags)result;
+    return 0;
+  }
+
+  int sign = 1;
+  if (*iter == CharT('-')) {
+    sign = -1;
+    result |= eParseHTMLInteger_Negative;
+    ++iter;
+  } else if (*iter == CharT('+')) {
+    result |= eParseHTMLInteger_NonStandard;
+    ++iter;
+  }
+
+  bool foundValue = false;
+  CheckedInt32 value = 0;
+
+  // Check for leading zeros first.
+  uint64_t leadingZeros = 0;
+  while (iter != aEnd) {
+    if (*iter != CharT('0')) {
+      break;
+    }
+
+    ++leadingZeros;
+    foundValue = true;
+    ++iter;
+  }
+
+  while (iter != aEnd) {
+    if (*iter >= CharT('0') && *iter <= CharT('9')) {
+      value = (value * 10) + (*iter - CharT('0')) * sign;
+      ++iter;
+      if (!value.isValid()) {
+        result |= eParseHTMLInteger_Error | eParseHTMLInteger_ErrorOverflow;
+        break;
+      }
+      foundValue = true;
+    } else {
+      break;
+    }
+  }
+
+  if (!foundValue) {
+    result |= eParseHTMLInteger_Error | eParseHTMLInteger_ErrorNoValue;
+  }
+
+  if (value.isValid() &&
+      ((leadingZeros > 1 || (leadingZeros == 1 && !(value == 0))) ||
+       (sign == -1 && value == 0))) {
+    result |= eParseHTMLInteger_NonStandard;
+  }
+
+  if (iter != aEnd) {
+    result |= eParseHTMLInteger_DidNotConsumeAllInput;
+  }
+
+  *aResult = (ParseHTMLIntegerResultFlags)result;
+  return value.isValid() ? value.value() : 0;
+}
+
+// Parse an integer according to HTML spec
+int32_t nsContentUtils::ParseHTMLInteger(const char16_t* aStart,
+                                         const char16_t* aEnd,
+                                         ParseHTMLIntegerResultFlags* aResult) {
+  return ParseHTMLIntegerImpl(aStart, aEnd, aResult);
+}
+
+int32_t nsContentUtils::ParseHTMLInteger(const char* aStart, const char* aEnd,
+                                         ParseHTMLIntegerResultFlags* aResult) {
+  return ParseHTMLIntegerImpl(aStart, aEnd, aResult);
+}
+
+#define SKIP_WHITESPACE(iter, end_iter, end_res)                 \
+  while ((iter) != (end_iter) && nsCRT::IsAsciiSpace(*(iter))) { \
+    ++(iter);                                                    \
+  }                                                              \
+  if ((iter) == (end_iter)) {                                    \
+    return (end_res);                                            \
+  }
+
+#define SKIP_ATTR_NAME(iter, end_iter)                            \
+  while ((iter) != (end_iter) && !nsCRT::IsAsciiSpace(*(iter)) && \
+         *(iter) != '=') {                                        \
+    ++(iter);                                                     \
+  }
+
+bool nsContentUtils::GetPseudoAttributeValue(const nsString& aSource,
+                                             nsAtom* aName, nsAString& aValue) {
+  aValue.Truncate();
+
+  const char16_t* start = aSource.get();
+  const char16_t* end = start + aSource.Length();
+  const char16_t* iter;
+
+  while (start != end) {
+    SKIP_WHITESPACE(start, end, false)
+    iter = start;
+    SKIP_ATTR_NAME(iter, end)
+
+    if (start == iter) {
+      return false;
+    }
+
+    // Remember the attr name.
+    const nsDependentSubstring& attrName = Substring(start, iter);
+
+    // Now check whether this is a valid name="value" pair.
+    start = iter;
+    SKIP_WHITESPACE(start, end, false)
+    if (*start != '=') {
+      // No '=', so this is not a name="value" pair.  We don't know
+      // what it is, and we have no way to handle it.
+      return false;
+    }
+
+    // Have to skip the value.
+    ++start;
+    SKIP_WHITESPACE(start, end, false)
+    char16_t q = *start;
+    if (q != kQuote && q != kApostrophe) {
+      // Not a valid quoted value, so bail.
+      return false;
+    }
+
+    ++start;  // Point to the first char of the value.
+    iter = start;
+
+    while (iter != end && *iter != q) {
+      ++iter;
+    }
+
+    if (iter == end) {
+      // Oops, unterminated quoted string.
+      return false;
+    }
+
+    // At this point attrName holds the name of the "attribute" and
+    // the value is between start and iter.
+
+    if (aName->Equals(attrName)) {
+      // We'll accumulate as many characters as possible (until we hit either
+      // the end of the string or the beginning of an entity). Chunks will be
+      // delimited by start and chunkEnd.
+      const char16_t* chunkEnd = start;
+      while (chunkEnd != iter) {
+        if (*chunkEnd == kLessThan) {
+          aValue.Truncate();
+
+          return false;
+        }
+
+        if (*chunkEnd == kAmpersand) {
+          aValue.Append(start, chunkEnd - start);
+
+          const char16_t* afterEntity = nullptr;
+          char16_t result[2];
+          uint32_t count = MOZ_XMLTranslateEntity(
+              reinterpret_cast<const char*>(chunkEnd),
+              reinterpret_cast<const char*>(iter),
+              reinterpret_cast<const char**>(&afterEntity), result);
+          if (count == 0) {
+            aValue.Truncate();
+
+            return false;
+          }
+
+          aValue.Append(result, count);
+
+          // Advance to after the entity and begin a new chunk.
+          start = chunkEnd = afterEntity;
+        } else {
+          ++chunkEnd;
+        }
+      }
+
+      // Append remainder.
+      aValue.Append(start, iter - start);
+
+      return true;
+    }
+
+    // Resume scanning after the end of the attribute value (past the quote
+    // char).
+    start = iter + 1;
+  }
+
+  return false;
+}
+
+bool nsContentUtils::IsJavaScriptLanguage(const nsString& aName) {
+  // Create MIME type as "text/" + given input
+  nsAutoString mimeType(u"text/");
+  mimeType.Append(aName);
+
+  return IsJavascriptMIMEType(mimeType);
+}
+
+void nsContentUtils::SplitMimeType(const nsAString& aValue, nsString& aType,
+                                   nsString& aParams) {
+  aType.Truncate();
+  aParams.Truncate();
+  int32_t semiIndex = aValue.FindChar(char16_t(';'));
+  if (-1 != semiIndex) {
+    aType = Substring(aValue, 0, semiIndex);
+    aParams =
+        Substring(aValue, semiIndex + 1, aValue.Length() - (semiIndex + 1));
+    aParams.StripWhitespace();
+  } else {
+    aType = aValue;
+  }
+  aType.StripWhitespace();
+}
+
+/**
+ * A helper function that parses a sandbox attribute (of an <iframe> or a CSP
+ * directive) and converts it to the set of flags used internally.
+ *
+ * @param aSandboxAttr  the sandbox attribute
+ * @return              the set of flags (SANDBOXED_NONE if aSandboxAttr is
+ *                      null)
+ */
+uint32_t nsContentUtils::ParseSandboxAttributeToFlags(
+    const nsAttrValue* aSandboxAttr) {
+  if (!aSandboxAttr) {
+    return SANDBOXED_NONE;
+  }
+
+  uint32_t out = SANDBOX_ALL_FLAGS;
+
+#define SANDBOX_KEYWORD(string, atom, flags)                  \
+  if (aSandboxAttr->Contains(nsGkAtoms::atom, eIgnoreCase)) { \
+    out &= ~(flags);                                          \
+  }
+#include "IframeSandboxKeywordList.h"
+#undef SANDBOX_KEYWORD
+
+  return out;
+}
+
+/**
+ * A helper function that checks if a string matches a valid sandbox flag.
+ *
+ * @param aFlag   the potential sandbox flag.
+ * @return        true if the flag is a sandbox flag.
+ */
+bool nsContentUtils::IsValidSandboxFlag(const nsAString& aFlag) {
+#define SANDBOX_KEYWORD(string, atom, flags)                                  \
+  if (EqualsIgnoreASCIICase(nsDependentAtomString(nsGkAtoms::atom), aFlag)) { \
+    return true;                                                              \
+  }
+#include "IframeSandboxKeywordList.h"
+#undef SANDBOX_KEYWORD
+  return false;
+}
+
+/**
+ * A helper function that returns a string attribute corresponding to the
+ * sandbox flags.
+ *
+ * @param aFlags    the sandbox flags
+ * @param aString   the attribute corresponding to the flags (null if aFlags
+ *                  is zero)
+ */
+void nsContentUtils::SandboxFlagsToString(uint32_t aFlags, nsAString& aString) {
+  if (!aFlags) {
+    SetDOMStringToNull(aString);
+    return;
+  }
+
+  aString.Truncate();
+
+#define SANDBOX_KEYWORD(string, atom, flags)                \
+  if (!(aFlags & (flags))) {                                \
+    if (!aString.IsEmpty()) {                               \
+      aString.AppendLiteral(u" ");                          \
+    }                                                       \
+    aString.Append(nsDependentAtomString(nsGkAtoms::atom)); \
+  }
+#include "IframeSandboxKeywordList.h"
+#undef SANDBOX_KEYWORD
+}
+
+nsIBidiKeyboard* nsContentUtils::GetBidiKeyboard() {
+  if (!sBidiKeyboard) {
+    sBidiKeyboard = nsIWidget::CreateBidiKeyboard();
+  }
+  return sBidiKeyboard;
+}
+
+/**
+ * This is used to determine whether a character is in one of the classes
+ * which CSS says should be part of the first-letter.  Currently, that is
+ * all punctuation classes (P*).  Note that this is a change from CSS2
+ * which excluded Pc and Pd.
+ *
+ * https://www.w3.org/TR/css-pseudo-4/#first-letter-pseudo
+ * "Punctuation (i.e, characters that belong to the Punctuation (P*) Unicode
+ *  general category [UAX44]) [...]"
+ */
+
+// static
+bool nsContentUtils::IsFirstLetterPunctuation(uint32_t aChar) {
+  switch (mozilla::unicode::GetGeneralCategory(aChar)) {
+    case HB_UNICODE_GENERAL_CATEGORY_CONNECT_PUNCTUATION: /* Pc */
+    case HB_UNICODE_GENERAL_CATEGORY_DASH_PUNCTUATION:    /* Pd */
+    case HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION:   /* Pe */
+    case HB_UNICODE_GENERAL_CATEGORY_FINAL_PUNCTUATION:   /* Pf */
+    case HB_UNICODE_GENERAL_CATEGORY_INITIAL_PUNCTUATION: /* Pi */
+    case HB_UNICODE_GENERAL_CATEGORY_OTHER_PUNCTUATION:   /* Po */
+    case HB_UNICODE_GENERAL_CATEGORY_OPEN_PUNCTUATION:    /* Ps */
+      return true;
+    default:
+      return false;
+  }
+}
+
+// static
+bool nsContentUtils::IsAlphanumeric(uint32_t aChar) {
+  nsUGenCategory cat = mozilla::unicode::GetGenCategory(aChar);
+
+  return (cat == nsUGenCategory::kLetter || cat == nsUGenCategory::kNumber);
+}
+
+// static
+bool nsContentUtils::IsAlphanumericOrSymbol(uint32_t aChar) {
+  nsUGenCategory cat = mozilla::unicode::GetGenCategory(aChar);
+
+  return cat == nsUGenCategory::kLetter || cat == nsUGenCategory::kNumber ||
+         cat == nsUGenCategory::kSymbol;
+}
+
+/* static */
+bool nsContentUtils::IsHTMLWhitespace(char16_t aChar) {
+  return aChar == char16_t(0x0009) || aChar == char16_t(0x000A) ||
+         aChar == char16_t(0x000C) || aChar == char16_t(0x000D) ||
+         aChar == char16_t(0x0020);
+}
+
+/* static */
+bool nsContentUtils::IsHTMLWhitespaceOrNBSP(char16_t aChar) {
+  return IsHTMLWhitespace(aChar) || aChar == char16_t(0xA0);
+}
+
+/* static */
+bool nsContentUtils::IsHTMLBlockLevelElement(nsIContent* aContent) {
+  return aContent->IsAnyOfHTMLElements(
+      nsGkAtoms::address, nsGkAtoms::article, nsGkAtoms::aside,
+      nsGkAtoms::blockquote, nsGkAtoms::center, nsGkAtoms::dir, nsGkAtoms::div,
+      nsGkAtoms::dl,  // XXX why not dt and dd?
+      nsGkAtoms::fieldset,
+      nsGkAtoms::figure,  // XXX shouldn't figcaption be on this list
+      nsGkAtoms::footer, nsGkAtoms::form, nsGkAtoms::h1, nsGkAtoms::h2,
+      nsGkAtoms::h3, nsGkAtoms::h4, nsGkAtoms::h5, nsGkAtoms::h6,
+      nsGkAtoms::header, nsGkAtoms::hgroup, nsGkAtoms::hr, nsGkAtoms::li,
+      nsGkAtoms::listing, nsGkAtoms::menu, nsGkAtoms::nav, nsGkAtoms::ol,
+      nsGkAtoms::p, nsGkAtoms::pre, nsGkAtoms::section, nsGkAtoms::table,
+      nsGkAtoms::ul, nsGkAtoms::xmp);
+}
+
+/* static */
+bool nsContentUtils::ParseIntMarginValue(const nsAString& aString,
+                                         nsIntMargin& result) {
+  nsAutoString marginStr(aString);
+  marginStr.CompressWhitespace(true, true);
+  if (marginStr.IsEmpty()) {
+    return false;
+  }
+
+  int32_t start = 0, end = 0;
+  for (int count = 0; count < 4; count++) {
+    if ((uint32_t)end >= marginStr.Length()) return false;
+
+    // top, right, bottom, left
+    if (count < 3)
+      end = Substring(marginStr, start).FindChar(',');
+    else
+      end = Substring(marginStr, start).Length();
+
+    if (end <= 0) return false;
+
+    nsresult ec;
+    int32_t val = nsString(Substring(marginStr, start, end)).ToInteger(&ec);
+    if (NS_FAILED(ec)) return false;
+
+    switch (count) {
+      case 0:
+        result.top = val;
+        break;
+      case 1:
+        result.right = val;
+        break;
+      case 2:
+        result.bottom = val;
+        break;
+      case 3:
+        result.left = val;
+        break;
+    }
+    start += end + 1;
+  }
+  return true;
+}
+
+// static
+int32_t nsContentUtils::ParseLegacyFontSize(const nsAString& aValue) {
+  nsAString::const_iterator iter, end;
+  aValue.BeginReading(iter);
+  aValue.EndReading(end);
+
+  while (iter != end && nsContentUtils::IsHTMLWhitespace(*iter)) {
+    ++iter;
+  }
+
+  if (iter == end) {
+    return 0;
+  }
+
+  bool relative = false;
+  bool negate = false;
+  if (*iter == char16_t('-')) {
+    relative = true;
+    negate = true;
+    ++iter;
+  } else if (*iter == char16_t('+')) {
+    relative = true;
+    ++iter;
+  }
+
+  if (iter == end || *iter < char16_t('0') || *iter > char16_t('9')) {
+    return 0;
+  }
+
+  // We don't have to worry about overflow, since we can bail out as soon as
+  // we're bigger than 7.
+  int32_t value = 0;
+  while (iter != end && *iter >= char16_t('0') && *iter <= char16_t('9')) {
+    value = 10 * value + (*iter - char16_t('0'));
+    if (value >= 7) {
+      break;
+    }
+    ++iter;
+  }
+
+  if (relative) {
+    if (negate) {
+      value = 3 - value;
+    } else {
+      value = 3 + value;
+    }
+  }
+
+  return clamped(value, 1, 7);
+}
+
+/* static */
+void nsContentUtils::GetOfflineAppManifest(Document* aDocument, nsIURI** aURI) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aDocument);
+  *aURI = nullptr;
+
+  if (aDocument->GetController().isSome()) {
+    return;
+  }
+
+  Element* docElement = aDocument->GetRootElement();
+  if (!docElement) {
+    return;
+  }
+
+  nsAutoString manifestSpec;
+  docElement->GetAttr(kNameSpaceID_None, nsGkAtoms::manifest, manifestSpec);
+
+  // Manifest URIs can't have fragment identifiers.
+  if (manifestSpec.IsEmpty() || manifestSpec.Contains('#')) {
+    return;
+  }
+
+  nsContentUtils::NewURIWithDocumentCharset(aURI, manifestSpec, aDocument,
+                                            aDocument->GetDocBaseURI());
+}
+
+/* static */
+bool nsContentUtils::OfflineAppAllowed(nsIURI* aURI) { return false; }
+
+/* static */
+bool nsContentUtils::OfflineAppAllowed(nsIPrincipal* aPrincipal) {
+  return false;
+}
+// Static
+bool nsContentUtils::IsErrorPage(nsIURI* aURI) {
+  if (!aURI) {
+    return false;
+  }
+
+  if (!aURI->SchemeIs("about")) {
+    return false;
+  }
+
+  nsAutoCString name;
+  nsresult rv = NS_GetAboutModuleName(aURI, name);
+  NS_ENSURE_SUCCESS(rv, false);
+
+  return name.EqualsLiteral("certerror") || name.EqualsLiteral("neterror") ||
+         name.EqualsLiteral("blocked");
+}
+
+// static
+void nsContentUtils::Shutdown() {
+  sInitialized = false;
+
+  nsHTMLTags::ReleaseTable();
+
+  NS_IF_RELEASE(sContentPolicyService);
+  sTriedToGetContentPolicy = false;
+  for (StaticRefPtr<nsIStringBundle>& bundle : sStringBundles) {
+    bundle = nullptr;
+  }
+
+  NS_IF_RELEASE(sStringBundleService);
+  NS_IF_RELEASE(sConsoleService);
+  NS_IF_RELEASE(sXPConnect);
+  NS_IF_RELEASE(sSecurityManager);
+  NS_IF_RELEASE(sSystemPrincipal);
+  NS_IF_RELEASE(sNullSubjectPrincipal);
+
+  sBidiKeyboard = nullptr;
+
+  delete sAtomEventTable;
+  sAtomEventTable = nullptr;
+  delete sStringEventTable;
+  sStringEventTable = nullptr;
+  delete sUserDefinedEvents;
+  sUserDefinedEvents = nullptr;
+
+  if (sEventListenerManagersHash) {
+    NS_ASSERTION(sEventListenerManagersHash->EntryCount() == 0,
+                 "Event listener manager hash not empty at shutdown!");
+
+    // See comment above.
+
+    // However, we have to handle this table differently.  If it still
+    // has entries, we want to leak it too, so that we can keep it alive
+    // in case any elements are destroyed.  Because if they are, we need
+    // their event listener managers to be destroyed too, or otherwise
+    // it could leave dangling references in DOMClassInfo's preserved
+    // wrapper table.
+
+    if (sEventListenerManagersHash->EntryCount() == 0) {
+      delete sEventListenerManagersHash;
+      sEventListenerManagersHash = nullptr;
+    }
+  }
+
+  if (sDOMArenaHashtable) {
+    MOZ_ASSERT(sDOMArenaHashtable->Count() == 0);
+    MOZ_ASSERT(StaticPrefs::dom_arena_allocator_enabled_AtStartup());
+    delete sDOMArenaHashtable;
+    sDOMArenaHashtable = nullptr;
+  }
+
+  NS_ASSERTION(!sBlockedScriptRunners || sBlockedScriptRunners->Length() == 0,
+               "How'd this happen?");
+  delete sBlockedScriptRunners;
+  sBlockedScriptRunners = nullptr;
+
+  delete sShiftText;
+  sShiftText = nullptr;
+  delete sControlText;
+  sControlText = nullptr;
+  delete sMetaText;
+  sMetaText = nullptr;
+  delete sOSText;
+  sOSText = nullptr;
+  delete sAltText;
+  sAltText = nullptr;
+  delete sModifierSeparator;
+  sModifierSeparator = nullptr;
+
+  delete sJSScriptBytecodeMimeType;
+  sJSScriptBytecodeMimeType = nullptr;
+
+  delete sJSModuleBytecodeMimeType;
+  sJSModuleBytecodeMimeType = nullptr;
+
+  NS_IF_RELEASE(sSameOriginChecker);
+
+  if (sUserInteractionObserver) {
+    sUserInteractionObserver->Shutdown();
+    NS_RELEASE(sUserInteractionObserver);
+  }
+
+  for (const auto& pref : kRfpPrefs) {
+    Preferences::UnregisterCallback(RecomputeResistFingerprintingAllDocs, pref);
+  }
+
+  TextControlState::Shutdown();
+  nsMappedAttributes::Shutdown();
+}
+
+/**
+ * Checks whether two nodes come from the same origin. aTrustedNode is
+ * considered 'safe' in that a user can operate on it.
+ */
+// static
+nsresult nsContentUtils::CheckSameOrigin(const nsINode* aTrustedNode,
+                                         const nsINode* unTrustedNode) {
+  MOZ_ASSERT(aTrustedNode);
+  MOZ_ASSERT(unTrustedNode);
+
+  /*
+   * Get hold of each node's principal
+   */
+
+  nsIPrincipal* trustedPrincipal = aTrustedNode->NodePrincipal();
+  nsIPrincipal* unTrustedPrincipal = unTrustedNode->NodePrincipal();
+
+  if (trustedPrincipal == unTrustedPrincipal) {
+    return NS_OK;
+  }
+
+  bool equal;
+  // XXXbz should we actually have a Subsumes() check here instead?  Or perhaps
+  // a separate method for that, with callers using one or the other?
+  if (NS_FAILED(trustedPrincipal->Equals(unTrustedPrincipal, &equal)) ||
+      !equal) {
+    return NS_ERROR_DOM_PROP_ACCESS_DENIED;
+  }
+
+  return NS_OK;
+}
+
+// static
+bool nsContentUtils::CanCallerAccess(nsIPrincipal* aSubjectPrincipal,
+                                     nsIPrincipal* aPrincipal) {
+  bool subsumes;
+  nsresult rv = aSubjectPrincipal->Subsumes(aPrincipal, &subsumes);
+  NS_ENSURE_SUCCESS(rv, false);
+
+  if (subsumes) {
+    return true;
+  }
+
+  // The subject doesn't subsume aPrincipal. Allow access only if the subject
+  // is chrome.
+  return IsCallerChrome();
+}
+
+// static
+bool nsContentUtils::CanCallerAccess(const nsINode* aNode) {
+  nsIPrincipal* subject = SubjectPrincipal();
+  if (subject->IsSystemPrincipal()) {
+    return true;
+  }
+
+  if (aNode->ChromeOnlyAccess()) {
+    return false;
+  }
+
+  return CanCallerAccess(subject, aNode->NodePrincipal());
+}
+
+// static
+bool nsContentUtils::CanCallerAccess(nsPIDOMWindowInner* aWindow) {
+  nsCOMPtr<nsIScriptObjectPrincipal> scriptObject = do_QueryInterface(aWindow);
+  NS_ENSURE_TRUE(scriptObject, false);
+
+  return CanCallerAccess(SubjectPrincipal(), scriptObject->GetPrincipal());
+}
+
+// static
+bool nsContentUtils::PrincipalHasPermission(nsIPrincipal& aPrincipal,
+                                            const nsAtom* aPerm) {
+  // Chrome gets access by default.
+  if (aPrincipal.IsSystemPrincipal()) {
+    return true;
+  }
+
+  // Otherwise, only allow if caller is an addon with the permission.
+  return BasePrincipal::Cast(aPrincipal).AddonHasPermission(aPerm);
+}
+
+// static
+bool nsContentUtils::CallerHasPermission(JSContext* aCx, const nsAtom* aPerm) {
+  return PrincipalHasPermission(*SubjectPrincipal(aCx), aPerm);
+}
+
+// static
+nsIPrincipal* nsContentUtils::GetAttrTriggeringPrincipal(
+    nsIContent* aContent, const nsAString& aAttrValue,
+    nsIPrincipal* aSubjectPrincipal) {
+  nsIPrincipal* contentPrin = aContent ? aContent->NodePrincipal() : nullptr;
+
+  // If the subject principal is the same as the content principal, or no
+  // explicit subject principal was provided, we don't need to do any further
+  // checks. Just return the content principal.
+  if (contentPrin == aSubjectPrincipal || !aSubjectPrincipal) {
+    return contentPrin;
+  }
+
+  // Only use the subject principal if the URL string we are going to end up
+  // fetching is under the control of that principal, which is never the case
+  // for relative URLs.
+  if (aAttrValue.IsEmpty() ||
+      !IsAbsoluteURL(NS_ConvertUTF16toUTF8(aAttrValue))) {
+    return contentPrin;
+  }
+
+  // Only use the subject principal as the attr triggering principal if it
+  // should override the CSP of the node's principal.
+  if (BasePrincipal::Cast(aSubjectPrincipal)->OverridesCSP(contentPrin)) {
+    return aSubjectPrincipal;
+  }
+
+  return contentPrin;
+}
+
+// static
+bool nsContentUtils::IsAbsoluteURL(const nsACString& aURL) {
+  nsAutoCString scheme;
+  if (NS_FAILED(net_ExtractURLScheme(aURL, scheme))) {
+    // If we can't extract a scheme, it's not an absolute URL.
+    return false;
+  }
+
+  // If it parses as an absolute StandardURL, it's definitely an absolute URL,
+  // so no need to check with the IO service.
+  if (net_IsAbsoluteURL(aURL)) {
+    return true;
+  }
+
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIIOService> io = mozilla::components::IO::Service(&rv);
+  MOZ_DIAGNOSTIC_ASSERT(NS_SUCCEEDED(rv));
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  uint32_t flags;
+  if (NS_SUCCEEDED(io->GetProtocolFlags(scheme.get(), &flags))) {
+    return flags & nsIProtocolHandler::URI_NORELATIVE;
+  }
+
+  return false;
+}
+
+// static
+bool nsContentUtils::InProlog(nsINode* aNode) {
+  MOZ_ASSERT(aNode, "missing node to nsContentUtils::InProlog");
+
+  nsINode* parent = aNode->GetParentNode();
+  if (!parent || !parent->IsDocument()) {
+    return false;
+  }
+
+  const Document* doc = parent->AsDocument();
+  const nsIContent* root = doc->GetRootElement();
+  if (!root) {
+    return true;
+  }
+  const Maybe<uint32_t> indexOfNode = doc->ComputeIndexOf(aNode);
+  const Maybe<uint32_t> indexOfRoot = doc->ComputeIndexOf(root);
+  if (MOZ_LIKELY(indexOfNode.isSome() && indexOfRoot.isSome())) {
+    return *indexOfNode < *indexOfRoot;
+  }
+  // XXX Keep the odd traditional behavior for now.
+  return indexOfNode.isNothing() && indexOfRoot.isSome();
+}
+
+bool nsContentUtils::IsCallerChrome() {
+  MOZ_ASSERT(NS_IsMainThread());
+  return SubjectPrincipal() == sSystemPrincipal;
+}
+
+#ifdef FUZZING
+bool nsContentUtils::IsFuzzingEnabled() {
+  return StaticPrefs::fuzzing_enabled();
+}
+#endif
+
+/* static */
+bool nsContentUtils::IsCallerChromeOrElementTransformGettersEnabled(
+    JSContext* aCx, JSObject*) {
+  return ThreadsafeIsSystemCaller(aCx) ||
+         StaticPrefs::dom_element_transform_getters_enabled();
+}
+
+// Older Should RFP Functions ----------------------------------
+
+/* static */
+bool nsContentUtils::ShouldResistFingerprinting(
+    RFPTarget aTarget /* = RFPTarget::Unknown */) {
+  return nsRFPService::IsRFPEnabledFor(aTarget);
+}
+
+/* static */
+bool nsContentUtils::ShouldResistFingerprinting(nsIGlobalObject* aGlobalObject,
+                                                RFPTarget aTarget) {
+  if (!aGlobalObject) {
+    return ShouldResistFingerprinting("Null Object", aTarget);
+  }
+  return aGlobalObject->ShouldResistFingerprinting(aTarget);
+}
+
+// Newer Should RFP Functions ----------------------------------
+// Utilities ---------------------------------------------------
+
+inline void LogDomainAndPrefList(const char* urlType,
+                                 const char* exemptedDomainsPrefName,
+                                 nsAutoCString& url, bool isExemptDomain) {
+  nsAutoCString list;
+  Preferences::GetCString(exemptedDomainsPrefName, list);
+  MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Debug,
+          ("%s \"%s\" is %s the exempt list \"%s\"", urlType,
+           PromiseFlatCString(url).get(), isExemptDomain ? "in" : "NOT in",
+           PromiseFlatCString(list).get()));
+}
+
+inline already_AddRefed<nsICookieJarSettings> GetCookieJarSettings(
+    nsILoadInfo* aLoadInfo) {
+  nsCOMPtr<nsICookieJarSettings> cookieJarSettings;
+  nsresult rv =
+      aLoadInfo->GetCookieJarSettings(getter_AddRefs(cookieJarSettings));
+  if (rv == NS_ERROR_NOT_IMPLEMENTED) {
+    // The TRRLoadInfo in particular does not implement this method
+    // In that instance.  We will return false and let other code decide if
+    // we shouldRFP for this connection
+    return nullptr;
+  }
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
+            ("Called CookieJarSettingsSaysShouldResistFingerprinting but the "
+             "loadinfo's CookieJarSettings couldn't be retrieved"));
+    return nullptr;
+  }
+
+  MOZ_ASSERT(cookieJarSettings);
+  return cookieJarSettings.forget();
+}
+
+bool ETPSaysShouldNotResistFingerprinting(nsIChannel* aChannel,
+                                          nsILoadInfo* aLoadInfo) {
+  // A positive return from this function should always be obeyed.
+  // A negative return means we should keep checking things.
+
+  // We do not want this check to apply to RFP, only to FPP
+  // There is one problematic combination of prefs; however:
+  // If RFP is enabled in PBMode only and FPP is enabled globally
+  // (so, in non-PBM mode) - we need to know if we're in PBMode or not.
+  // But that's kind of expensive and we'd like to avoid it if we
+  // don't have to, so special-case that scenario
+  if (StaticPrefs::privacy_fingerprintingProtection_DoNotUseDirectly() &&
+      !StaticPrefs::privacy_resistFingerprinting_DoNotUseDirectly() &&
+      StaticPrefs::privacy_resistFingerprinting_pbmode_DoNotUseDirectly()) {
+    if (NS_UsePrivateBrowsing(aChannel)) {
+      // In PBM (where RFP is enabled) do not exempt based on the ETP toggle
+      return false;
+    }
+  } else if (StaticPrefs::privacy_resistFingerprinting_DoNotUseDirectly() ||
+             StaticPrefs::
+                 privacy_resistFingerprinting_pbmode_DoNotUseDirectly()) {
+    // In RFP, never use the ETP toggle to exempt.
+    // We can safely return false here even if we are not in PBM mode
+    // and RFP_pbmode is enabled because we will later see that and
+    // return false from the ShouldRFP function entirely.
+    return false;
+  }
+
+  nsCOMPtr<nsICookieJarSettings> cookieJarSettings =
+      GetCookieJarSettings(aLoadInfo);
+  if (!cookieJarSettings) {
+    return false;
+  }
+
+  return ContentBlockingAllowList::Check(cookieJarSettings);
+}
+
+inline bool CookieJarSettingsSaysShouldResistFingerprinting(
+    nsILoadInfo* aLoadInfo) {
+  // A positive return from this function should always be obeyed.
+  // A negative return means we should keep checking things.
+
+  nsCOMPtr<nsICookieJarSettings> cookieJarSettings =
+      GetCookieJarSettings(aLoadInfo);
+  if (!cookieJarSettings) {
+    return false;
+  }
+  return cookieJarSettings->GetShouldResistFingerprinting();
+}
+
+inline bool SchemeSaysShouldNotResistFingerprinting(nsIURI* aURI) {
+  return aURI->SchemeIs("chrome") || aURI->SchemeIs("resource") ||
+         aURI->SchemeIs("view-source") || aURI->SchemeIs("moz-extension") ||
+         (aURI->SchemeIs("about") && !NS_IsContentAccessibleAboutURI(aURI));
+}
+
+inline bool SchemeSaysShouldNotResistFingerprinting(nsIPrincipal* aPrincipal) {
+  if (aPrincipal->SchemeIs("chrome") || aPrincipal->SchemeIs("resource") ||
+      aPrincipal->SchemeIs("view-source") ||
+      aPrincipal->SchemeIs("moz-extension")) {
+    return true;
+  }
+
+  if (!aPrincipal->SchemeIs("about")) {
+    return false;
+  }
+
+  bool isContentAccessibleAboutURI;
+  Unused << aPrincipal->IsContentAccessibleAboutURI(
+      &isContentAccessibleAboutURI);
+  return !isContentAccessibleAboutURI;
+}
+
+const char* kExemptedDomainsPrefName =
+    "privacy.resistFingerprinting.exemptedDomains";
+
+inline bool PartionKeyIsAlsoExempted(
+    const mozilla::OriginAttributes& aOriginAttributes) {
+  // If we've gotten here we have (probably) passed the CookieJarSettings
+  // check that would tell us that if we _are_ a subdocument, then we are on
+  // an exempted top-level domain and we should see if we ourselves are
+  // exempted. But we may have gotten here because we directly called the
+  // _dangerous function and we haven't done that check, but we _were_
+  // instatiated from a state where we could have been partitioned.
+  // So perform this last-ditch check for that scenario.
+  // We arbitrarily use https as the scheme, but it doesn't matter.
+  nsresult rv = NS_ERROR_NOT_INITIALIZED;
+  nsCOMPtr<nsIURI> uri;
+  if (StaticPrefs::privacy_firstparty_isolate() &&
+      !aOriginAttributes.mFirstPartyDomain.IsEmpty()) {
+    rv = NS_NewURI(getter_AddRefs(uri),
+                   u"https://"_ns + aOriginAttributes.mFirstPartyDomain);
+  } else if (!aOriginAttributes.mPartitionKey.IsEmpty()) {
+    rv = NS_NewURI(getter_AddRefs(uri),
+                   u"https://"_ns + aOriginAttributes.mPartitionKey);
+  }
+
+  if (!NS_FAILED(rv)) {
+    bool isExemptPartitionKey =
+        nsContentUtils::IsURIInPrefList(uri, kExemptedDomainsPrefName);
+    if (MOZ_LOG_TEST(nsContentUtils::ResistFingerprintingLog(),
+                     mozilla::LogLevel::Debug)) {
+      nsAutoCString url;
+      uri->GetHost(url);
+      LogDomainAndPrefList("Partition Key", kExemptedDomainsPrefName, url,
+                           isExemptPartitionKey);
+    }
+    return isExemptPartitionKey;
+  }
+  return true;
+}
+
+// Functions ---------------------------------------------------
+
+/* static */
+bool nsContentUtils::ShouldResistFingerprinting(
+    const char* aJustification, RFPTarget aTarget /* = RFPTarget::Unknown */) {
+  // See comment in header file for information about usage
+  return ShouldResistFingerprinting(aTarget);
+}
+
+/* static */
+bool nsContentUtils::ShouldResistFingerprinting(
+    CallerType aCallerType, nsIGlobalObject* aGlobalObject,
+    RFPTarget aTarget /* = RFPTarget::Unknown */) {
+  if (aCallerType == CallerType::System) {
+    return false;
+  }
+  return ShouldResistFingerprinting(aGlobalObject, aTarget);
+}
+
+bool nsContentUtils::ShouldResistFingerprinting(nsIDocShell* aDocShell,
+                                                RFPTarget aTarget) {
+  if (!aDocShell) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
+            ("Called nsContentUtils::ShouldResistFingerprinting(nsIDocShell*) "
+             "with NULL docshell"));
+    return ShouldResistFingerprinting("Null Object", aTarget);
+  }
+  Document* doc = aDocShell->GetDocument();
+  if (!doc) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
+            ("Called nsContentUtils::ShouldResistFingerprinting(nsIDocShell*) "
+             "with NULL doc"));
+    return ShouldResistFingerprinting(aTarget);
+  }
+  return doc->ShouldResistFingerprinting(aTarget);
+}
+
+/* static */
+bool nsContentUtils::ShouldResistFingerprinting(
+    nsIChannel* aChannel, RFPTarget aTarget /* = RFPTarget::Unknown */) {
+  if (!aChannel) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
+            ("Called nsContentUtils::ShouldResistFingerprinting(nsIChannel* "
+             "aChannel) with NULL channel"));
+    return ShouldResistFingerprinting("Null Object", aTarget);
+  }
+
+  nsCOMPtr<nsILoadInfo> loadInfo = aChannel->LoadInfo();
+  if (!loadInfo) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
+            ("Called nsContentUtils::ShouldResistFingerprinting(nsIChannel* "
+             "aChannel) but the channel's loadinfo was NULL"));
+    return ShouldResistFingerprinting("Null Object", aTarget);
+  }
+
+  // With this check, we can ensure that the prefs and target say yes, so only
+  // an exemption would cause us to return false.
+  if (!ShouldResistFingerprinting("Positive return check", aTarget)) {
+    return false;
+  }
+
+  if (ETPSaysShouldNotResistFingerprinting(aChannel, loadInfo)) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Debug,
+            ("Inside ShouldResistFingerprinting(nsIChannel*)"
+             " ETPSaysShouldNotResistFingerprinting said false"));
+    return false;
+  }
+
+  if (CookieJarSettingsSaysShouldResistFingerprinting(loadInfo)) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Debug,
+            ("Inside ShouldResistFingerprinting(nsIChannel*)"
+             " CookieJarSettingsSaysShouldResistFingerprinting said true"));
+    return true;
+  }
+
+  // Document types have no loading principal.  Subdocument types do have a
+  // loading principal, but it is the loading principal of the parent
+  // document; not the subdocument.
+  auto contentType = loadInfo->GetExternalContentPolicyType();
+  // Case 1: Document or Subdocument load
+  if (contentType == ExtContentPolicy::TYPE_DOCUMENT ||
+      contentType == ExtContentPolicy::TYPE_SUBDOCUMENT) {
+    nsCOMPtr<nsIURI> channelURI;
+    nsresult rv = NS_GetFinalChannelURI(aChannel, getter_AddRefs(channelURI));
+    MOZ_ASSERT(
+        NS_SUCCEEDED(rv),
+        "Failed to get URI in "
+        "nsContentUtils::ShouldResistFingerprinting(nsIChannel* aChannel)");
+    // this check is to ensure that we do not crash in non-debug builds.
+    if (NS_FAILED(rv)) {
+      return true;
+    }
+
+#if 0
+  if (loadInfo->GetExternalContentPolicyType() == ExtContentPolicy::TYPE_SUBDOCUMENT) {
+    nsCOMPtr<nsIURI> channelURI;
+    nsresult rv = NS_GetFinalChannelURI(aChannel, getter_AddRefs(channelURI));
+    nsAutoCString channelSpec;
+    channelURI->GetSpec(channelSpec);
+
+    if (!loadInfo->GetLoadingPrincipal()) {
+        MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
+            ("Sub Document Type.  FinalChannelURI is %s, Loading Principal is NULL\n",
+                channelSpec.get()));
+
+    } else {
+        nsAutoCString loadingPrincipalSpec;
+        loadInfo->GetLoadingPrincipal()->GetOrigin(loadingPrincipalSpec);
+
+        MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
+            ("Sub Document Type.  FinalChannelURI is %s, Loading Principal Origin is %s\n",
+                channelSpec.get(), loadingPrincipalSpec.get()));
+    }
+  }
+
+#endif
+
+    return ShouldResistFingerprinting_dangerous(
+        channelURI, loadInfo->GetOriginAttributes(), "Internal Call", aTarget);
+  }
+
+  // Case 2: Subresource Load
+  // Because this code is only used for subresource loads, this
+  // will check the parent's principal
+  nsIPrincipal* principal = loadInfo->GetLoadingPrincipal();
+
+  MOZ_ASSERT_IF(principal && !principal->IsSystemPrincipal() &&
+                    !principal->GetIsAddonOrExpandedAddonPrincipal(),
+                BasePrincipal::Cast(principal)->OriginAttributesRef() ==
+                    loadInfo->GetOriginAttributes());
+  return ShouldResistFingerprinting_dangerous(principal, "Internal Call",
+                                              aTarget);
+}
+
+/* static */
+bool nsContentUtils::ShouldResistFingerprinting_dangerous(
+    nsIURI* aURI, const mozilla::OriginAttributes& aOriginAttributes,
+    const char* aJustification, RFPTarget aTarget /* = RFPTarget::Unknown */) {
+  // With this check, we can ensure that the prefs and target say yes, so only
+  // an exemption would cause us to return false.
+  if (!ShouldResistFingerprinting("Positive return check", aTarget)) {
+    return false;
+  }
+
+  MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Debug,
+          ("Inside ShouldResistFingerprinting_dangerous(nsIURI*,"
+           " OriginAttributes) and the URI is %s",
+           aURI->GetSpecOrDefault().get()));
+
+  if (!StaticPrefs::privacy_resistFingerprinting_DoNotUseDirectly() &&
+      !StaticPrefs::privacy_fingerprintingProtection_DoNotUseDirectly()) {
+    // If neither of the 'regular' RFP prefs are set, then one (or both)
+    // of the PBM-Only prefs are set (or we would have failed the
+    // Positive return check.)  Therefore, if we are not in PBM, return false
+    if (aOriginAttributes.mPrivateBrowsingId == 0) {
+      return false;
+    }
+  }
+
+  // Exclude internal schemes and web extensions
+  if (SchemeSaysShouldNotResistFingerprinting(aURI)) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Debug,
+            ("Inside ShouldResistFingerprinting(nsIURI*)"
+             " SchemeSaysShouldNotResistFingerprinting said false"));
+    return false;
+  }
+
+  bool isExemptDomain = false;
+  nsAutoCString list;
+  Preferences::GetCString(kExemptedDomainsPrefName, list);
+  ToLowerCase(list);
+  isExemptDomain = IsURIInList(aURI, list);
+
+  if (MOZ_LOG_TEST(nsContentUtils::ResistFingerprintingLog(),
+                   mozilla::LogLevel::Debug)) {
+    nsAutoCString url;
+    aURI->GetHost(url);
+    LogDomainAndPrefList("URI", kExemptedDomainsPrefName, url, isExemptDomain);
+  }
+
+  if (isExemptDomain) {
+    isExemptDomain &= PartionKeyIsAlsoExempted(aOriginAttributes);
+  }
+
+  return !isExemptDomain;
+}
+
+/* static */
+bool nsContentUtils::ShouldResistFingerprinting_dangerous(
+    nsIPrincipal* aPrincipal, const char* aJustification,
+    RFPTarget aTarget /* = RFPTarget::Unknown */) {
+  if (!aPrincipal) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
+            ("Called nsContentUtils::ShouldResistFingerprinting(nsILoadInfo* "
+             "aChannel) but the loadinfo's loadingprincipal was NULL"));
+    return ShouldResistFingerprinting("Null object", aTarget);
+  }
+
+  // With this check, we can ensure that the prefs and target say yes, so only
+  // an exemption would cause us to return false.
+  if (!ShouldResistFingerprinting("Positive return check", aTarget)) {
+    return false;
+  }
+
+  if (aPrincipal->IsSystemPrincipal()) {
+    return false;
+  }
+
+  auto originAttributes =
+      BasePrincipal::Cast(aPrincipal)->OriginAttributesRef();
+  if (!StaticPrefs::privacy_resistFingerprinting_DoNotUseDirectly() &&
+      !StaticPrefs::privacy_fingerprintingProtection_DoNotUseDirectly()) {
+    // If neither of the 'regular' RFP prefs are set, then one (or both)
+    // of the PBM-Only prefs are set (or we would have failed the
+    // Positive return check.)  Therefore, if we are not in PBM, return false
+    if (originAttributes.mPrivateBrowsingId == 0) {
+      return false;
+    }
+  }
+
+  // Exclude internal schemes and web extensions
+  if (SchemeSaysShouldNotResistFingerprinting(aPrincipal)) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Debug,
+            ("Inside ShouldResistFingerprinting(nsIPrincipal*)"
+             " SchemeSaysShouldNotResistFingerprinting said false"));
+    return false;
+  }
+
+  // Web extension principals are also excluded
+  if (BasePrincipal::Cast(aPrincipal)->AddonPolicy()) {
+    MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Debug,
+            ("Inside ShouldResistFingerprinting_dangerous(nsIPrincipal*)"
+             " and AddonPolicy said false"));
+    return false;
+  }
+
+  bool isExemptDomain = false;
+  aPrincipal->IsURIInPrefList(kExemptedDomainsPrefName, &isExemptDomain);
+
+  if (MOZ_LOG_TEST(nsContentUtils::ResistFingerprintingLog(),
+                   mozilla::LogLevel::Debug)) {
+    nsAutoCString origin;
+    aPrincipal->GetAsciiOrigin(origin);
+    LogDomainAndPrefList("URI", kExemptedDomainsPrefName, origin,
+                         isExemptDomain);
+  }
+
+  if (isExemptDomain) {
+    isExemptDomain &= PartionKeyIsAlsoExempted(originAttributes);
+  }
+
+  // If we've gotten here we have (probably) passed the CookieJarSettings
+  // check that would tell us that if we _are_ a subdocument, then we are on
+  // an exempted top-level domain and we should see if we ourselves are
+  // exempted. But we may have gotten here because we directly called the
+  // _dangerous function and we haven't done that check, but we _were_
+  // instatiated from a state where we could have been partitioned.
+  // So perform this last-ditch check for that scenario.
+  // We arbitrarily use https as the scheme, but it doesn't matter.
+  nsCOMPtr<nsIURI> uri;
+  if (isExemptDomain && StaticPrefs::privacy_firstparty_isolate() &&
+      !originAttributes.mFirstPartyDomain.IsEmpty()) {
+    nsresult rv =
+        NS_NewURI(getter_AddRefs(uri),
+                  u"https://"_ns + originAttributes.mFirstPartyDomain);
+    if (!NS_FAILED(rv)) {
+      isExemptDomain =
+          nsContentUtils::IsURIInPrefList(uri, kExemptedDomainsPrefName);
+    }
+  } else if (isExemptDomain && !originAttributes.mPartitionKey.IsEmpty()) {
+    nsresult rv = NS_NewURI(getter_AddRefs(uri),
+                            u"https://"_ns + originAttributes.mPartitionKey);
+    if (!NS_FAILED(rv)) {
+      isExemptDomain =
+          nsContentUtils::IsURIInPrefList(uri, kExemptedDomainsPrefName);
+    }
+  }
+
+  return !isExemptDomain;
+}
+
+// --------------------------------------------------------------------
+
+/* static */
+void nsContentUtils::CalcRoundedWindowSizeForResistingFingerprinting(
+    int32_t aChromeWidth, int32_t aChromeHeight, int32_t aScreenWidth,
+    int32_t aScreenHeight, int32_t aInputWidth, int32_t aInputHeight,
+    bool aSetOuterWidth, bool aSetOuterHeight, int32_t* aOutputWidth,
+    int32_t* aOutputHeight) {
+  MOZ_ASSERT(aOutputWidth);
+  MOZ_ASSERT(aOutputHeight);
+
+  int32_t availContentWidth = 0;
+  int32_t availContentHeight = 0;
+
+  availContentWidth = std::min(StaticPrefs::privacy_window_maxInnerWidth(),
+                               aScreenWidth - aChromeWidth);
+#ifdef MOZ_WIDGET_GTK
+  // In the GTK window, it will not report outside system decorations
+  // when we get available window size, see Bug 581863. So, we leave a
+  // 40 pixels space for them when calculating the available content
+  // height. It is not necessary for the width since the content width
+  // is usually pretty much the same as the chrome width.
+  availContentHeight = std::min(StaticPrefs::privacy_window_maxInnerHeight(),
+                                (-40 + aScreenHeight) - aChromeHeight);
+#else
+  availContentHeight = std::min(StaticPrefs::privacy_window_maxInnerHeight(),
+                                aScreenHeight - aChromeHeight);
+#endif
+
+  // Ideally, we'd like to round window size to 1000x1000, but the
+  // screen space could be too small to accommodate this size in some
+  // cases. If it happens, we would round the window size to the nearest
+  // 200x100.
+  availContentWidth = availContentWidth - (availContentWidth % 200);
+  availContentHeight = availContentHeight - (availContentHeight % 100);
+
+  // If aIsOuter is true, we are setting the outer window. So we
+  // have to consider the chrome UI.
+  int32_t chromeOffsetWidth = aSetOuterWidth ? aChromeWidth : 0;
+  int32_t chromeOffsetHeight = aSetOuterHeight ? aChromeHeight : 0;
+  int32_t resultWidth = 0, resultHeight = 0;
+
+  // if the original size is greater than the maximum available size, we set
+  // it to the maximum size. And if the original value is less than the
+  // minimum rounded size, we set it to the minimum 200x100.
+  if (aInputWidth > (availContentWidth + chromeOffsetWidth)) {
+    resultWidth = availContentWidth + chromeOffsetWidth;
+  } else if (aInputWidth < (200 + chromeOffsetWidth)) {
+    resultWidth = 200 + chromeOffsetWidth;
+  } else {
+    // Otherwise, we round the window to the nearest upper rounded 200x100.
+    resultWidth = NSToIntCeil((aInputWidth - chromeOffsetWidth) / 200.0) * 200 +
+                  chromeOffsetWidth;
+  }
+
+  if (aInputHeight > (availContentHeight + chromeOffsetHeight)) {
+    resultHeight = availContentHeight + chromeOffsetHeight;
+  } else if (aInputHeight < (100 + chromeOffsetHeight)) {
+    resultHeight = 100 + chromeOffsetHeight;
+  } else {
+    resultHeight =
+        NSToIntCeil((aInputHeight - chromeOffsetHeight) / 100.0) * 100 +
+        chromeOffsetHeight;
+  }
+
+  *aOutputWidth = resultWidth;
+  *aOutputHeight = resultHeight;
+}
+
+bool nsContentUtils::ThreadsafeIsCallerChrome() {
+  return NS_IsMainThread() ? IsCallerChrome()
+                           : IsCurrentThreadRunningChromeWorker();
+}
+
+bool nsContentUtils::IsCallerUAWidget() {
+  JSContext* cx = GetCurrentJSContext();
+  if (!cx) {
+    return false;
+  }
+
+  JS::Realm* realm = JS::GetCurrentRealmOrNull(cx);
+  if (!realm) {
+    return false;
+  }
+
+  return xpc::IsUAWidgetScope(realm);
+}
+
+bool nsContentUtils::IsSystemCaller(JSContext* aCx) {
+  // Note that SubjectPrincipal() assumes we are in a compartment here.
+  return SubjectPrincipal(aCx) == sSystemPrincipal;
+}
+
+bool nsContentUtils::ThreadsafeIsSystemCaller(JSContext* aCx) {
+  CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get();
+  MOZ_ASSERT(ccjscx->Context() == aCx);
+
+  return ccjscx->IsSystemCaller();
+}
+
+// static
+bool nsContentUtils::LookupBindingMember(
+    JSContext* aCx, nsIContent* aContent, JS::Handle<jsid> aId,
+    JS::MutableHandle<JS::PropertyDescriptor> aDesc) {
+  return true;
+}
+
+nsINode* nsContentUtils::GetNearestInProcessCrossDocParentNode(
+    nsINode* aChild) {
+  if (aChild->IsDocument()) {
+    for (BrowsingContext* bc = aChild->AsDocument()->GetBrowsingContext(); bc;
+         bc = bc->GetParent()) {
+      if (bc->GetEmbedderElement()) {
+        return bc->GetEmbedderElement();
+      }
+    }
+    return nullptr;
+  }
+
+  nsINode* parent = aChild->GetParentNode();
+  if (parent && parent->IsContent() && aChild->IsContent()) {
+    parent = aChild->AsContent()->GetFlattenedTreeParent();
+  }
+
+  return parent;
+}
+
+bool nsContentUtils::ContentIsHostIncludingDescendantOf(
+    const nsINode* aPossibleDescendant, const nsINode* aPossibleAncestor) {
+  MOZ_ASSERT(aPossibleDescendant, "The possible descendant is null!");
+  MOZ_ASSERT(aPossibleAncestor, "The possible ancestor is null!");
+
+  do {
+    if (aPossibleDescendant == aPossibleAncestor) return true;
+    if (aPossibleDescendant->IsDocumentFragment()) {
+      aPossibleDescendant =
+          aPossibleDescendant->AsDocumentFragment()->GetHost();
+    } else {
+      aPossibleDescendant = aPossibleDescendant->GetParentNode();
+    }
+  } while (aPossibleDescendant);
+
+  return false;
+}
+
+// static
+bool nsContentUtils::ContentIsCrossDocDescendantOf(nsINode* aPossibleDescendant,
+                                                   nsINode* aPossibleAncestor) {
+  MOZ_ASSERT(aPossibleDescendant, "The possible descendant is null!");
+  MOZ_ASSERT(aPossibleAncestor, "The possible ancestor is null!");
+
+  do {
+    if (aPossibleDescendant == aPossibleAncestor) {
+      return true;
+    }
+
+    aPossibleDescendant =
+        GetNearestInProcessCrossDocParentNode(aPossibleDescendant);
+  } while (aPossibleDescendant);
+
+  return false;
+}
+
+// static
+bool nsContentUtils::ContentIsFlattenedTreeDescendantOf(
+    const nsINode* aPossibleDescendant, const nsINode* aPossibleAncestor) {
+  MOZ_ASSERT(aPossibleDescendant, "The possible descendant is null!");
+  MOZ_ASSERT(aPossibleAncestor, "The possible ancestor is null!");
+
+  do {
+    if (aPossibleDescendant == aPossibleAncestor) {
+      return true;
+    }
+    aPossibleDescendant = aPossibleDescendant->GetFlattenedTreeParentNode();
+  } while (aPossibleDescendant);
+
+  return false;
+}
+
+// static
+bool nsContentUtils::ContentIsFlattenedTreeDescendantOfForStyle(
+    const nsINode* aPossibleDescendant, const nsINode* aPossibleAncestor) {
+  MOZ_ASSERT(aPossibleDescendant, "The possible descendant is null!");
+  MOZ_ASSERT(aPossibleAncestor, "The possible ancestor is null!");
+
+  do {
+    if (aPossibleDescendant == aPossibleAncestor) {
+      return true;
+    }
+    aPossibleDescendant =
+        aPossibleDescendant->GetFlattenedTreeParentNodeForStyle();
+  } while (aPossibleDescendant);
+
+  return false;
+}
+
+// static
+nsINode* nsContentUtils::Retarget(nsINode* aTargetA, nsINode* aTargetB) {
+  while (true && aTargetA) {
+    // If A's root is not a shadow root...
+    nsINode* root = aTargetA->SubtreeRoot();
+    if (!root->IsShadowRoot()) {
+      // ...then return A.
+      return aTargetA;
+    }
+
+    // or A's root is a shadow-including inclusive ancestor of B...
+    if (aTargetB->IsShadowIncludingInclusiveDescendantOf(root)) {
+      // ...then return A.
+      return aTargetA;
+    }
+
+    aTargetA = ShadowRoot::FromNode(root)->GetHost();
+  }
+
+  return nullptr;
+}
+
+// static
+Element* nsContentUtils::GetAnElementForTiming(Element* aTarget,
+                                               const Document* aDocument,
+                                               nsIGlobalObject* aGlobal) {
+  if (!aTarget->IsInComposedDoc()) {
+    return nullptr;
+  }
+
+  if (!aDocument) {
+    nsCOMPtr<nsPIDOMWindowInner> inner = do_QueryInterface(aGlobal);
+    if (!inner) {
+      return nullptr;
+    }
+    aDocument = inner->GetExtantDoc();
+  }
+
+  MOZ_ASSERT(aDocument);
+
+  if (aTarget->GetUncomposedDocOrConnectedShadowRoot() != aDocument ||
+      !aDocument->IsCurrentActiveDocument()) {
+    return nullptr;
+  }
+
+  return aTarget;
+}
+
+// static
+nsresult nsContentUtils::GetInclusiveAncestors(nsINode* aNode,
+                                               nsTArray<nsINode*>& aArray) {
+  while (aNode) {
+    aArray.AppendElement(aNode);
+    aNode = aNode->GetParentNode();
+  }
+  return NS_OK;
+}
+
+// static
+nsresult nsContentUtils::GetInclusiveAncestorsAndOffsets(
+    nsINode* aNode, uint32_t aOffset, nsTArray<nsIContent*>* aAncestorNodes,
+    nsTArray<Maybe<uint32_t>>* aAncestorOffsets) {
+  NS_ENSURE_ARG_POINTER(aNode);
+
+  if (!aNode->IsContent()) {
+    return NS_ERROR_FAILURE;
+  }
+  nsIContent* content = aNode->AsContent();
+
+  if (!aAncestorNodes->IsEmpty()) {
+    NS_WARNING("aAncestorNodes is not empty");
+    aAncestorNodes->Clear();
+  }
+
+  if (!aAncestorOffsets->IsEmpty()) {
+    NS_WARNING("aAncestorOffsets is not empty");
+    aAncestorOffsets->Clear();
+  }
+
+  // insert the node itself
+  aAncestorNodes->AppendElement(content);
+  aAncestorOffsets->AppendElement(Some(aOffset));
+
+  // insert all the ancestors
+  nsIContent* child = content;
+  nsIContent* parent = child->GetParent();
+  while (parent) {
+    aAncestorNodes->AppendElement(parent);
+    aAncestorOffsets->AppendElement(parent->ComputeIndexOf(child));
+    child = parent;
+    parent = parent->GetParent();
+  }
+
+  return NS_OK;
+}
+
+template <typename Node, typename GetParentFunc>
+static Node* GetCommonAncestorInternal(Node* aNode1, Node* aNode2,
+                                       GetParentFunc aGetParentFunc) {
+  MOZ_ASSERT(aNode1 != aNode2);
+
+  // Build the chain of parents
+  AutoTArray<Node*, 30> parents1, parents2;
+  do {
+    parents1.AppendElement(aNode1);
+    aNode1 = aGetParentFunc(aNode1);
+  } while (aNode1);
+  do {
+    parents2.AppendElement(aNode2);
+    aNode2 = aGetParentFunc(aNode2);
+  } while (aNode2);
+
+  // Find where the parent chain differs
+  uint32_t pos1 = parents1.Length();
+  uint32_t pos2 = parents2.Length();
+  Node* parent = nullptr;
+  uint32_t len;
+  for (len = std::min(pos1, pos2); len > 0; --len) {
+    Node* child1 = parents1.ElementAt(--pos1);
+    Node* child2 = parents2.ElementAt(--pos2);
+    if (child1 != child2) {
+      break;
+    }
+    parent = child1;
+  }
+
+  return parent;
+}
+
+/* static */
+nsINode* nsContentUtils::GetCommonAncestorHelper(nsINode* aNode1,
+                                                 nsINode* aNode2) {
+  return GetCommonAncestorInternal(
+      aNode1, aNode2, [](nsINode* aNode) { return aNode->GetParentNode(); });
+}
+
+/* static */
+nsIContent* nsContentUtils::GetCommonFlattenedTreeAncestorHelper(
+    nsIContent* aContent1, nsIContent* aContent2) {
+  return GetCommonAncestorInternal(
+      aContent1, aContent2,
+      [](nsIContent* aContent) { return aContent->GetFlattenedTreeParent(); });
+}
+
+/* static */
+Element* nsContentUtils::GetCommonFlattenedTreeAncestorForStyle(
+    Element* aElement1, Element* aElement2) {
+  return GetCommonAncestorInternal(aElement1, aElement2, [](Element* aElement) {
+    return aElement->GetFlattenedTreeParentElementForStyle();
+  });
+}
+
+/* static */
+bool nsContentUtils::PositionIsBefore(nsINode* aNode1, nsINode* aNode2,
+                                      Maybe<uint32_t>* aNode1Index,
+                                      Maybe<uint32_t>* aNode2Index) {
+  // Note, CompareDocumentPosition takes the latter params in different order.
+  return (aNode2->CompareDocumentPosition(*aNode1, aNode2Index, aNode1Index) &
+          (Node_Binding::DOCUMENT_POSITION_PRECEDING |
+           Node_Binding::DOCUMENT_POSITION_DISCONNECTED)) ==
+         Node_Binding::DOCUMENT_POSITION_PRECEDING;
+}
+
+/* static */
+Maybe<int32_t> nsContentUtils::ComparePoints(
+    const nsINode* aParent1, uint32_t aOffset1, const nsINode* aParent2,
+    uint32_t aOffset2, ComparePointsCache* aParent1Cache) {
+  bool disconnected{false};
+
+  const int32_t order = ComparePoints_Deprecated(
+      aParent1, aOffset1, aParent2, aOffset2, &disconnected, aParent1Cache);
+  if (disconnected) {
+    return Nothing();
+  }
+
+  return Some(order);
+}
+
+/* static */
+int32_t nsContentUtils::ComparePoints_Deprecated(
+    const nsINode* aParent1, uint32_t aOffset1, const nsINode* aParent2,
+    uint32_t aOffset2, bool* aDisconnected, ComparePointsCache* aParent1Cache) {
+  if (aParent1 == aParent2) {
+    return aOffset1 < aOffset2 ? -1 : aOffset1 > aOffset2 ? 1 : 0;
+  }
+
+  AutoTArray<const nsINode*, 32> parents1, parents2;
+  const nsINode* node1 = aParent1;
+  const nsINode* node2 = aParent2;
+  do {
+    parents1.AppendElement(node1);
+    node1 = node1->GetParentOrShadowHostNode();
+  } while (node1);
+  do {
+    parents2.AppendElement(node2);
+    node2 = node2->GetParentOrShadowHostNode();
+  } while (node2);
+
+  uint32_t pos1 = parents1.Length() - 1;
+  uint32_t pos2 = parents2.Length() - 1;
+
+  bool disconnected = parents1.ElementAt(pos1) != parents2.ElementAt(pos2);
+  if (aDisconnected) {
+    *aDisconnected = disconnected;
+  }
+  if (disconnected) {
+    NS_ASSERTION(aDisconnected, "unexpected disconnected nodes");
+    return 1;
+  }
+
+  // Find where the parent chains differ
+  const nsINode* parent = parents1.ElementAt(pos1);
+  uint32_t len;
+  for (len = std::min(pos1, pos2); len > 0; --len) {
+    const nsINode* child1 = parents1.ElementAt(--pos1);
+    const nsINode* child2 = parents2.ElementAt(--pos2);
+    if (child1 != child2) {
+      if (MOZ_UNLIKELY(child1->IsShadowRoot())) {
+        // Shadow roots come before light DOM per
+        // https://dom.spec.whatwg.org/#concept-shadow-including-tree-order
+        MOZ_ASSERT(!child2->IsShadowRoot(), "Two shadow roots?");
+        return -1;
+      }
+      if (MOZ_UNLIKELY(child2->IsShadowRoot())) {
+        return 1;
+      }
+      const Maybe<uint32_t> child1Index =
+          aParent1Cache ? aParent1Cache->ComputeIndexOf(parent, child1)
+                        : parent->ComputeIndexOf(child1);
+      const Maybe<uint32_t> child2Index = parent->ComputeIndexOf(child2);
+      if (MOZ_LIKELY(child1Index.isSome() && child2Index.isSome())) {
+        return *child1Index < *child2Index ? -1 : 1;
+      }
+      // XXX Keep the odd traditional behavior for now.
+      return child1Index.isNothing() && child2Index.isSome() ? -1 : 1;
+    }
+    parent = child1;
+  }
+
+  // The parent chains never differed, so one of the nodes is an ancestor of
+  // the other
+
+  NS_ASSERTION(!pos1 || !pos2,
+               "should have run out of parent chain for one of the nodes");
+
+  if (!pos1) {
+    const nsINode* child2 = parents2.ElementAt(--pos2);
+    const Maybe<uint32_t> child2Index = parent->ComputeIndexOf(child2);
+    if (MOZ_UNLIKELY(NS_WARN_IF(child2Index.isNothing()))) {
+      return 1;
+    }
+    return aOffset1 <= *child2Index ? -1 : 1;
+  }
+
+  const nsINode* child1 = parents1.ElementAt(--pos1);
+  const Maybe<uint32_t> child1Index =
+      aParent1Cache ? aParent1Cache->ComputeIndexOf(parent, child1)
+                    : parent->ComputeIndexOf(child1);
+  if (MOZ_UNLIKELY(NS_WARN_IF(child1Index.isNothing()))) {
+    return -1;
+  }
+  return *child1Index < aOffset2 ? -1 : 1;
+}
+
+// static
+nsINode* nsContentUtils::GetCommonAncestorUnderInteractiveContent(
+    nsINode* aNode1, nsINode* aNode2) {
+  if (!aNode1 || !aNode2) {
+    return nullptr;
+  }
+
+  if (aNode1 == aNode2) {
+    return aNode1;
+  }
+
+  // Build the chain of parents
+  AutoTArray<nsINode*, 30> parents1;
+  do {
+    parents1.AppendElement(aNode1);
+    if (aNode1->IsElement() &&
+        aNode1->AsElement()->IsInteractiveHTMLContent()) {
+      break;
+    }
+    aNode1 = aNode1->GetFlattenedTreeParentNode();
+  } while (aNode1);
+
+  AutoTArray<nsINode*, 30> parents2;
+  do {
+    parents2.AppendElement(aNode2);
+    if (aNode2->IsElement() &&
+        aNode2->AsElement()->IsInteractiveHTMLContent()) {
+      break;
+    }
+    aNode2 = aNode2->GetFlattenedTreeParentNode();
+  } while (aNode2);
+
+  // Find where the parent chain differs
+  uint32_t pos1 = parents1.Length();
+  uint32_t pos2 = parents2.Length();
+  nsINode* parent = nullptr;
+  for (uint32_t len = std::min(pos1, pos2); len > 0; --len) {
+    nsINode* child1 = parents1.ElementAt(--pos1);
+    nsINode* child2 = parents2.ElementAt(--pos2);
+    if (child1 != child2) {
+      break;
+    }
+    parent = child1;
+  }
+
+  return parent;
+}
+
+/* static */
+BrowserParent* nsContentUtils::GetCommonBrowserParentAncestor(
+    BrowserParent* aBrowserParent1, BrowserParent* aBrowserParent2) {
+  return GetCommonAncestorInternal(
+      aBrowserParent1, aBrowserParent2, [](BrowserParent* aBrowserParent) {
+        return aBrowserParent->GetBrowserBridgeParent()
+                   ? aBrowserParent->GetBrowserBridgeParent()->Manager()
+                   : nullptr;
+      });
+}
+
+/* static */
+Element* nsContentUtils::GetTargetElement(Document* aDocument,
+                                          const nsAString& aAnchorName) {
+  MOZ_ASSERT(aDocument);
+
+  if (aAnchorName.IsEmpty()) {
+    return nullptr;
+  }
+  // 1. If there is an element in the document tree that has an ID equal to
+  //    fragment, then return the first such element in tree order.
+  if (Element* el = aDocument->GetElementById(aAnchorName)) {
+    return el;
+  }
+
+  // 2. If there is an a element in the document tree that has a name
+  // attribute whose value is equal to fragment, then return the first such
+  // element in tree order.
+  //
+  // FIXME(emilio): Why the different code-paths for HTML and non-HTML docs?
+  if (aDocument->IsHTMLDocument()) {
+    nsCOMPtr<nsINodeList> list = aDocument->GetElementsByName(aAnchorName);
+    // Loop through the named nodes looking for the first anchor
+    uint32_t length = list->Length();
+    for (uint32_t i = 0; i < length; i++) {
+      nsIContent* node = list->Item(i);
+      if (node->IsHTMLElement(nsGkAtoms::a)) {
+        return node->AsElement();
+      }
+    }
+  } else {
+    constexpr auto nameSpace = u"http://www.w3.org/1999/xhtml"_ns;
+    // Get the list of anchor elements
+    nsCOMPtr<nsINodeList> list =
+        aDocument->GetElementsByTagNameNS(nameSpace, u"a"_ns);
+    // Loop through the anchors looking for the first one with the given name.
+    for (uint32_t i = 0; true; i++) {
+      nsIContent* node = list->Item(i);
+      if (!node) {  // End of list
+        break;
+      }
+
+      // Compare the name attribute
+      if (node->AsElement()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::name,
+                                         aAnchorName, eCaseMatters)) {
+        return node->AsElement();
+      }
+    }
+  }
+
+  // 3. Return null.
+  return nullptr;
+}
+
+/* static */
+template <typename FPT, typename FRT, typename SPT, typename SRT>
+Maybe<int32_t> nsContentUtils::ComparePoints(
+    const RangeBoundaryBase<FPT, FRT>& aFirstBoundary,
+    const RangeBoundaryBase<SPT, SRT>& aSecondBoundary) {
+  if (!aFirstBoundary.IsSet() || !aSecondBoundary.IsSet()) {
+    return Nothing{};
+  }
+
+  bool disconnected{false};
+  const int32_t order =
+      ComparePoints_Deprecated(aFirstBoundary, aSecondBoundary, &disconnected);
+
+  if (disconnected) {
+    return Nothing{};
+  }
+
+  return Some(order);
+}
+
+/* static */
+template <typename FPT, typename FRT, typename SPT, typename SRT>
+int32_t nsContentUtils::ComparePoints_Deprecated(
+    const RangeBoundaryBase<FPT, FRT>& aFirstBoundary,
+    const RangeBoundaryBase<SPT, SRT>& aSecondBoundary, bool* aDisconnected) {
+  if (NS_WARN_IF(!aFirstBoundary.IsSet()) ||
+      NS_WARN_IF(!aSecondBoundary.IsSet())) {
+    return -1;
+  }
+  // XXX Re-implement this without calling `Offset()` as far as possible,
+  //     and the other overload should be an alias of this.
+  return ComparePoints_Deprecated(
+      aFirstBoundary.Container(),
+      *aFirstBoundary.Offset(
+          RangeBoundaryBase<FPT, FRT>::OffsetFilter::kValidOrInvalidOffsets),
+      aSecondBoundary.Container(),
+      *aSecondBoundary.Offset(
+          RangeBoundaryBase<SPT, SRT>::OffsetFilter::kValidOrInvalidOffsets),
+      aDisconnected);
+}
+
+inline bool IsCharInSet(const char* aSet, const char16_t aChar) {
+  char16_t ch;
+  while ((ch = *aSet)) {
+    if (aChar == char16_t(ch)) {
+      return true;
+    }
+    ++aSet;
+  }
+  return false;
+}
+
+/**
+ * This method strips leading/trailing chars, in given set, from string.
+ */
+
+// static
+const nsDependentSubstring nsContentUtils::TrimCharsInSet(
+    const char* aSet, const nsAString& aValue) {
+  nsAString::const_iterator valueCurrent, valueEnd;
+
+  aValue.BeginReading(valueCurrent);
+  aValue.EndReading(valueEnd);
+
+  // Skip characters in the beginning
+  while (valueCurrent != valueEnd) {
+    if (!IsCharInSet(aSet, *valueCurrent)) {
+      break;
+    }
+    ++valueCurrent;
+  }
+
+  if (valueCurrent != valueEnd) {
+    for (;;) {
+      --valueEnd;
+      if (!IsCharInSet(aSet, *valueEnd)) {
+        break;
+      }
+    }
+    ++valueEnd;  // Step beyond the last character we want in the value.
+  }
+
+  // valueEnd should point to the char after the last to copy
+  return Substring(valueCurrent, valueEnd);
+}
+
+/**
+ * This method strips leading and trailing whitespace from a string.
+ */
+
+// static
+template <bool IsWhitespace(char16_t)>
+const nsDependentSubstring nsContentUtils::TrimWhitespace(const nsAString& aStr,
+                                                          bool aTrimTrailing) {
+  nsAString::const_iterator start, end;
+
+  aStr.BeginReading(start);
+  aStr.EndReading(end);
+
+  // Skip whitespace characters in the beginning
+  while (start != end && IsWhitespace(*start)) {
+    ++start;
+  }
+
+  if (aTrimTrailing) {
+    // Skip whitespace characters in the end.
+    while (end != start) {
+      --end;
+
+      if (!IsWhitespace(*end)) {
+        // Step back to the last non-whitespace character.
+        ++end;
+
+        break;
+      }
+    }
+  }
+
+  // Return a substring for the string w/o leading and/or trailing
+  // whitespace
+
+  return Substring(start, end);
+}
+
+// Declaring the templates we are going to use avoid linking issues without
+// inlining the method. Considering there is not so much spaces checking
+// methods we can consider this to be better than inlining.
+template const nsDependentSubstring
+nsContentUtils::TrimWhitespace<nsCRT::IsAsciiSpace>(const nsAString&, bool);
+template const nsDependentSubstring nsContentUtils::TrimWhitespace<
+    nsContentUtils::IsHTMLWhitespace>(const nsAString&, bool);
+template const nsDependentSubstring nsContentUtils::TrimWhitespace<
+    nsContentUtils::IsHTMLWhitespaceOrNBSP>(const nsAString&, bool);
+
+static inline void KeyAppendSep(nsACString& aKey) {
+  if (!aKey.IsEmpty()) {
+    aKey.Append('>');
+  }
+}
+
+static inline void KeyAppendString(const nsAString& aString, nsACString& aKey) {
+  KeyAppendSep(aKey);
+
+  // Could escape separator here if collisions happen.  > is not a legal char
+  // for a name or type attribute, so we should be safe avoiding that extra
+  // work.
+
+  AppendUTF16toUTF8(aString, aKey);
+}
+
+static inline void KeyAppendString(const nsACString& aString,
+                                   nsACString& aKey) {
+  KeyAppendSep(aKey);
+
+  // Could escape separator here if collisions happen.  > is not a legal char
+  // for a name or type attribute, so we should be safe avoiding that extra
+  // work.
+
+  aKey.Append(aString);
+}
+
+static inline void KeyAppendInt(int32_t aInt, nsACString& aKey) {
+  KeyAppendSep(aKey);
+
+  aKey.AppendInt(aInt);
+}
+
+static inline bool IsAutocompleteOff(const nsIContent* aContent) {
+  return aContent->IsElement() &&
+         aContent->AsElement()->AttrValueIs(kNameSpaceID_None,
+                                            nsGkAtoms::autocomplete, u"off"_ns,
+                                            eIgnoreCase);
+}
+
+/*static*/
+void nsContentUtils::GenerateStateKey(nsIContent* aContent, Document* aDocument,
+                                      nsACString& aKey) {
+  MOZ_ASSERT(aContent);
+
+  aKey.Truncate();
+
+  uint32_t partID = aDocument ? aDocument->GetPartID() : 0;
+
+  // Don't capture state for anonymous content
+  if (aContent->IsInNativeAnonymousSubtree()) {
+    return;
+  }
+
+  if (IsAutocompleteOff(aContent)) {
+    return;
+  }
+
+  RefPtr<Document> doc = aContent->GetUncomposedDoc();
+
+  KeyAppendInt(partID, aKey);  // first append a partID
+  bool generatedUniqueKey = false;
+
+  if (doc && doc->IsHTMLOrXHTML()) {
+    nsHTMLDocument* htmlDoc = doc->AsHTMLDocument();
+
+    // If we have a form control and can calculate form information, use that
+    // as the key - it is more reliable than just recording position in the
+    // DOM.
+    // XXXbz Is it, really?  We have bugs on this, I think...
+    // Important to have a unique key, and tag/type/name may not be.
+    //
+    // The format of the key depends on whether the control has a form,
+    // and whether the element was parser inserted:
+    //
+    // [Has Form, Parser Inserted]:
+    //   fp>type>FormNum>IndOfControlInForm>FormName>name
+    //
+    // [No Form, Parser Inserted]:
+    //   dp>type>ControlNum>name
+    //
+    // [Has Form, Not Parser Inserted]:
+    //   fn>type>IndOfFormInDoc>IndOfControlInForm>FormName>name
+    //
+    // [No Form, Not Parser Inserted]:
+    //   dn>type>IndOfControlInDoc>name
+    //
+    // XXX We don't need to use index if name is there
+    // XXXbz We don't?  Why not?  I don't follow.
+    //
+    nsCOMPtr<nsIFormControl> control(do_QueryInterface(aContent));
+    if (control) {
+      // Get the control number if this was a parser inserted element from the
+      // network.
+      int32_t controlNumber =
+          control->GetParserInsertedControlNumberForStateKey();
+      bool parserInserted = controlNumber != -1;
+
+      RefPtr<nsContentList> htmlForms;
+      RefPtr<nsContentList> htmlFormControls;
+      if (!parserInserted) {
+        // Getting these lists is expensive, as we need to keep them up to date
+        // as the document loads, so we avoid it if we don't need them.
+        htmlDoc->GetFormsAndFormControls(getter_AddRefs(htmlForms),
+                                         getter_AddRefs(htmlFormControls));
+      }
+
+      // Append the control type
+      KeyAppendInt(int32_t(control->ControlType()), aKey);
+
+      // If in a form, add form name / index of form / index in form
+      HTMLFormElement* formElement = control->GetForm();
+      if (formElement) {
+        if (IsAutocompleteOff(formElement)) {
+          aKey.Truncate();
+          return;
+        }
+
+        // Append the form number, if this is a parser inserted control, or
+        // the index of the form in the document otherwise.
+        bool appendedForm = false;
+        if (parserInserted) {
+          MOZ_ASSERT(formElement->GetFormNumberForStateKey() != -1,
+                     "when generating a state key for a parser inserted form "
+                     "control we should have a parser inserted <form> element");
+          KeyAppendString("fp"_ns, aKey);
+          KeyAppendInt(formElement->GetFormNumberForStateKey(), aKey);
+          appendedForm = true;
+        } else {
+          KeyAppendString("fn"_ns, aKey);
+          int32_t index = htmlForms->IndexOf(formElement, false);
+          if (index <= -1) {
+            //
+            // XXX HACK this uses some state that was dumped into the document
+            // specifically to fix bug 138892.  What we are trying to do is
+            // *guess* which form this control's state is found in, with the
+            // highly likely guess that the highest form parsed so far is the
+            // one. This code should not be on trunk, only branch.
+            //
+            index = htmlDoc->GetNumFormsSynchronous() - 1;
+          }
+          if (index > -1) {
+            KeyAppendInt(index, aKey);
+            appendedForm = true;
+          }
+        }
+
+        if (appendedForm) {
+          // Append the index of the control in the form
+          int32_t index = formElement->IndexOfContent(aContent);
+
+          if (index > -1) {
+            KeyAppendInt(index, aKey);
+            generatedUniqueKey = true;
+          }
+        }
+
+        // Append the form name
+        nsAutoString formName;
+        formElement->GetAttr(kNameSpaceID_None, nsGkAtoms::name, formName);
+        KeyAppendString(formName, aKey);
+      } else {
+        // Not in a form.  Append the control number, if this is a parser
+        // inserted control, or the index of the control in the document
+        // otherwise.
+        if (parserInserted) {
+          KeyAppendString("dp"_ns, aKey);
+          KeyAppendInt(control->GetParserInsertedControlNumberForStateKey(),
+                       aKey);
+          generatedUniqueKey = true;
+        } else {
+          KeyAppendString("dn"_ns, aKey);
+          int32_t index = htmlFormControls->IndexOf(aContent, true);
+          if (index > -1) {
+            KeyAppendInt(index, aKey);
+            generatedUniqueKey = true;
+          }
+        }
+
+        // Append the control name
+        nsAutoString name;
+        aContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::name,
+                                       name);
+        KeyAppendString(name, aKey);
+      }
+    }
+  }
+
+  if (!generatedUniqueKey) {
+    // Either we didn't have a form control or we aren't in an HTML document so
+    // we can't figure out form info.  Append the tag name if it's an element
+    // to avoid restoring state for one type of element on another type.
+    if (aContent->IsElement()) {
+      KeyAppendString(nsDependentAtomString(aContent->NodeInfo()->NameAtom()),
+                      aKey);
+    } else {
+      // Append a character that is not "d" or "f" to disambiguate from
+      // the case when we were a form control in an HTML document.
+      KeyAppendString("o"_ns, aKey);
+    }
+
+    // Now start at aContent and append the indices of it and all its ancestors
+    // in their containers.  That should at least pin down its position in the
+    // DOM...
+    nsINode* parent = aContent->GetParentNode();
+    nsINode* content = aContent;
+    while (parent) {
+      KeyAppendInt(parent->ComputeIndexOf_Deprecated(content), aKey);
+      content = parent;
+      parent = content->GetParentNode();
+    }
+  }
+}
+
+// static
+nsIPrincipal* nsContentUtils::SubjectPrincipal(JSContext* aCx) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // As opposed to SubjectPrincipal(), we do in fact assume that
+  // we're in a realm here; anyone who calls this function in
+  // situations where that's not the case is doing it wrong.
+  JS::Realm* realm = js::GetContextRealm(aCx);
+  MOZ_ASSERT(realm);
+
+  JSPrincipals* principals = JS::GetRealmPrincipals(realm);
+  return nsJSPrincipals::get(principals);
+}
+
+// static
+nsIPrincipal* nsContentUtils::SubjectPrincipal() {
+  MOZ_ASSERT(IsInitialized());
+  MOZ_ASSERT(NS_IsMainThread());
+  JSContext* cx = GetCurrentJSContext();
+  if (!cx) {
+    MOZ_CRASH(
+        "Accessing the Subject Principal without an AutoJSAPI on the stack is "
+        "forbidden");
+  }
+
+  JS::Realm* realm = js::GetContextRealm(cx);
+
+  // When an AutoJSAPI is instantiated, we are in a null realm until the
+  // first JSAutoRealm, which is kind of a purgatory as far as permissions
+  // go. It would be nice to just hard-abort if somebody does a security check
+  // in this purgatory zone, but that would be too fragile, since it could be
+  // triggered by random IsCallerChrome() checks 20-levels deep.
+  //
+  // So we want to return _something_ here - and definitely not the System
+  // Principal, since that would make an AutoJSAPI a very dangerous thing to
+  // instantiate.
+  //
+  // The natural thing to return is a null principal. Ideally, we'd return a
+  // different null principal each time, to avoid any unexpected interactions
+  // when the principal accidentally gets inherited somewhere. But
+  // SubjectPrincipal doesn't return strong references, so there's no way to
+  // sanely manage the lifetime of multiple null principals.
+  //
+  // So we use a singleton null principal. To avoid it being accidentally
+  // inherited and becoming a "real" subject or object principal, we do a
+  // release-mode assert during realm creation against using this principal on
+  // an actual global.
+  if (!realm) {
+    return sNullSubjectPrincipal;
+  }
+
+  return SubjectPrincipal(cx);
+}
+
+// static
+nsIPrincipal* nsContentUtils::ObjectPrincipal(JSObject* aObj) {
+#ifdef DEBUG
+  JS::AssertObjectBelongsToCurrentThread(aObj);
+#endif
+
+  MOZ_DIAGNOSTIC_ASSERT(!js::IsCrossCompartmentWrapper(aObj));
+
+  JS::Realm* realm = js::GetNonCCWObjectRealm(aObj);
+  JSPrincipals* principals = JS::GetRealmPrincipals(realm);
+  return nsJSPrincipals::get(principals);
+}
+
+// static
+nsresult nsContentUtils::NewURIWithDocumentCharset(nsIURI** aResult,
+                                                   const nsAString& aSpec,
+                                                   Document* aDocument,
+                                                   nsIURI* aBaseURI) {
+  if (aDocument) {
+    return NS_NewURI(aResult, aSpec, aDocument->GetDocumentCharacterSet(),
+                     aBaseURI);
+  }
+  return NS_NewURI(aResult, aSpec, nullptr, aBaseURI);
+}
+
+// static
+bool nsContentUtils::IsNameWithDash(nsAtom* aName) {
+  // A valid custom element name is a sequence of characters name which
+  // must match the PotentialCustomElementName production:
+  // PotentialCustomElementName ::= [a-z] (PCENChar)* '-' (PCENChar)*
+  const char16_t* name = aName->GetUTF16String();
+  uint32_t len = aName->GetLength();
+  bool hasDash = false;
+
+  if (!len || name[0] < 'a' || name[0] > 'z') {
+    return false;
+  }
+
+  uint32_t i = 1;
+  while (i < len) {
+    if (i + 1 < len && NS_IS_SURROGATE_PAIR(name[i], name[i + 1])) {
+      // Merged two 16-bit surrogate pairs into code point.
+      char32_t code = SURROGATE_TO_UCS4(name[i], name[i + 1]);
+
+      if (code < 0x10000 || code > 0xEFFFF) {
+        return false;
+      }
+
+      i += 2;
+    } else {
+      if (name[i] == '-') {
+        hasDash = true;
+      }
+
+      if (name[i] != '-' && name[i] != '.' && name[i] != '_' &&
+          name[i] != 0xB7 && (name[i] < '0' || name[i] > '9') &&
+          (name[i] < 'a' || name[i] > 'z') &&
+          (name[i] < 0xC0 || name[i] > 0xD6) &&
+          (name[i] < 0xF8 || name[i] > 0x37D) &&
+          (name[i] < 0x37F || name[i] > 0x1FFF) &&
+          (name[i] < 0x200C || name[i] > 0x200D) &&
+          (name[i] < 0x203F || name[i] > 0x2040) &&
+          (name[i] < 0x2070 || name[i] > 0x218F) &&
+          (name[i] < 0x2C00 || name[i] > 0x2FEF) &&
+          (name[i] < 0x3001 || name[i] > 0xD7FF) &&
+          (name[i] < 0xF900 || name[i] > 0xFDCF) &&
+          (name[i] < 0xFDF0 || name[i] > 0xFFFD)) {
+        return false;
+      }
+
+      i++;
+    }
+  }
+
+  return hasDash;
+}
+
+// static
+bool nsContentUtils::IsCustomElementName(nsAtom* aName, uint32_t aNameSpaceID) {
+  // Allow non-dashed names in XUL for XBL to Custom Element migrations.
+  if (aNameSpaceID == kNameSpaceID_XUL) {
+    return true;
+  }
+
+  bool hasDash = IsNameWithDash(aName);
+  if (!hasDash) {
+    return false;
+  }
+
+  // The custom element name must not be one of the following values:
+  //  annotation-xml
+  //  color-profile
+  //  font-face
+  //  font-face-src
+  //  font-face-uri
+  //  font-face-format
+  //  font-face-name
+  //  missing-glyph
+  return aName != nsGkAtoms::annotation_xml_ &&
+         aName != nsGkAtoms::colorProfile && aName != nsGkAtoms::font_face &&
+         aName != nsGkAtoms::font_face_src &&
+         aName != nsGkAtoms::font_face_uri &&
+         aName != nsGkAtoms::font_face_format &&
+         aName != nsGkAtoms::font_face_name && aName != nsGkAtoms::missingGlyph;
+}
+
+// static
+nsresult nsContentUtils::CheckQName(const nsAString& aQualifiedName,
+                                    bool aNamespaceAware,
+                                    const char16_t** aColon) {
+  const char* colon = nullptr;
+  const char16_t* begin = aQualifiedName.BeginReading();
+  const char16_t* end = aQualifiedName.EndReading();
+
+  int result = MOZ_XMLCheckQName(reinterpret_cast<const char*>(begin),
+                                 reinterpret_cast<const char*>(end),
+                                 aNamespaceAware, &colon);
+
+  if (!result) {
+    if (aColon) {
+      *aColon = reinterpret_cast<const char16_t*>(colon);
+    }
+
+    return NS_OK;
+  }
+
+  return NS_ERROR_DOM_INVALID_CHARACTER_ERR;
+}
+
+// static
+nsresult nsContentUtils::SplitQName(const nsIContent* aNamespaceResolver,
+                                    const nsString& aQName, int32_t* aNamespace,
+                                    nsAtom** aLocalName) {
+  const char16_t* colon;
+  nsresult rv = nsContentUtils::CheckQName(aQName, true, &colon);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (colon) {
+    const char16_t* end;
+    aQName.EndReading(end);
+    nsAutoString nameSpace;
+    rv = aNamespaceResolver->LookupNamespaceURIInternal(
+        Substring(aQName.get(), colon), nameSpace);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    *aNamespace = nsNameSpaceManager::GetInstance()->GetNameSpaceID(
+        nameSpace, nsContentUtils::IsChromeDoc(aNamespaceResolver->OwnerDoc()));
+    if (*aNamespace == kNameSpaceID_Unknown) return NS_ERROR_FAILURE;
+
+    *aLocalName = NS_AtomizeMainThread(Substring(colon + 1, end)).take();
+  } else {
+    *aNamespace = kNameSpaceID_None;
+    *aLocalName = NS_AtomizeMainThread(aQName).take();
+  }
+  NS_ENSURE_TRUE(aLocalName, NS_ERROR_OUT_OF_MEMORY);
+  return NS_OK;
+}
+
+// static
+nsresult nsContentUtils::GetNodeInfoFromQName(
+    const nsAString& aNamespaceURI, const nsAString& aQualifiedName,
+    nsNodeInfoManager* aNodeInfoManager, uint16_t aNodeType,
+    mozilla::dom::NodeInfo** aNodeInfo) {
+  const nsString& qName = PromiseFlatString(aQualifiedName);
+  const char16_t* colon;
+  nsresult rv = nsContentUtils::CheckQName(qName, true, &colon);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  int32_t nsID;
+  nsNameSpaceManager::GetInstance()->RegisterNameSpace(aNamespaceURI, nsID);
+  if (colon) {
+    const char16_t* end;
+    qName.EndReading(end);
+
+    RefPtr<nsAtom> prefix = NS_AtomizeMainThread(Substring(qName.get(), colon));
+
+    rv = aNodeInfoManager->GetNodeInfo(Substring(colon + 1, end), prefix, nsID,
+                                       aNodeType, aNodeInfo);
+  } else {
+    rv = aNodeInfoManager->GetNodeInfo(aQualifiedName, nullptr, nsID, aNodeType,
+                                       aNodeInfo);
+  }
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return nsContentUtils::IsValidNodeName((*aNodeInfo)->NameAtom(),
+                                         (*aNodeInfo)->GetPrefixAtom(),
+                                         (*aNodeInfo)->NamespaceID())
+             ? NS_OK
+             : NS_ERROR_DOM_NAMESPACE_ERR;
+}
+
+// static
+void nsContentUtils::SplitExpatName(const char16_t* aExpatName,
+                                    nsAtom** aPrefix, nsAtom** aLocalName,
+                                    int32_t* aNameSpaceID) {
+  /**
+   *  Expat can send the following:
+   *    localName
+   *    namespaceURI<separator>localName
+   *    namespaceURI<separator>localName<separator>prefix
+   *
+   *  and we use 0xFFFF for the <separator>.
+   *
+   */
+
+  const char16_t* uriEnd = nullptr;
+  const char16_t* nameEnd = nullptr;
+  const char16_t* pos;
+  for (pos = aExpatName; *pos; ++pos) {
+    if (*pos == 0xFFFF) {
+      if (uriEnd) {
+        nameEnd = pos;
+      } else {
+        uriEnd = pos;
+      }
+    }
+  }
+
+  const char16_t* nameStart;
+  if (uriEnd) {
+    nsNameSpaceManager::GetInstance()->RegisterNameSpace(
+        nsDependentSubstring(aExpatName, uriEnd), *aNameSpaceID);
+
+    nameStart = (uriEnd + 1);
+    if (nameEnd) {
+      const char16_t* prefixStart = nameEnd + 1;
+      *aPrefix = NS_AtomizeMainThread(Substring(prefixStart, pos)).take();
+    } else {
+      nameEnd = pos;
+      *aPrefix = nullptr;
+    }
+  } else {
+    *aNameSpaceID = kNameSpaceID_None;
+    nameStart = aExpatName;
+    nameEnd = pos;
+    *aPrefix = nullptr;
+  }
+  *aLocalName = NS_AtomizeMainThread(Substring(nameStart, nameEnd)).take();
+}
+
+// static
+PresShell* nsContentUtils::GetPresShellForContent(const nsIContent* aContent) {
+  Document* doc = aContent->GetComposedDoc();
+  if (!doc) {
+    return nullptr;
+  }
+  return doc->GetPresShell();
+}
+
+// static
+nsPresContext* nsContentUtils::GetContextForContent(
+    const nsIContent* aContent) {
+  PresShell* presShell = GetPresShellForContent(aContent);
+  if (!presShell) {
+    return nullptr;
+  }
+  return presShell->GetPresContext();
+}
+
+// static
+bool nsContentUtils::CanLoadImage(nsIURI* aURI, nsINode* aNode,
+                                  Document* aLoadingDocument,
+                                  nsIPrincipal* aLoadingPrincipal) {
+  MOZ_ASSERT(aURI, "Must have a URI");
+  MOZ_ASSERT(aLoadingDocument, "Must have a document");
+  MOZ_ASSERT(aLoadingPrincipal, "Must have a loading principal");
+
+  nsresult rv;
+
+  auto appType = nsIDocShell::APP_TYPE_UNKNOWN;
+
+  {
+    nsCOMPtr<nsIDocShellTreeItem> docShellTreeItem =
+        aLoadingDocument->GetDocShell();
+    if (docShellTreeItem) {
+      nsCOMPtr<nsIDocShellTreeItem> root;
+      docShellTreeItem->GetInProcessRootTreeItem(getter_AddRefs(root));
+
+      nsCOMPtr<nsIDocShell> docShell(do_QueryInterface(root));
+
+      if (docShell) {
+        appType = docShell->GetAppType();
+      }
+    }
+  }
+
+  if (appType != nsIDocShell::APP_TYPE_EDITOR) {
+    // Editor apps get special treatment here, editors can load images
+    // from anywhere.  This allows editor to insert images from file://
+    // into documents that are being edited.
+    rv = sSecurityManager->CheckLoadURIWithPrincipal(
+        aLoadingPrincipal, aURI, nsIScriptSecurityManager::ALLOW_CHROME,
+        aLoadingDocument->InnerWindowID());
+    if (NS_FAILED(rv)) {
+      return false;
+    }
+  }
+
+  nsCOMPtr<nsILoadInfo> secCheckLoadInfo = new mozilla::net::LoadInfo(
+      aLoadingPrincipal,
+      aLoadingPrincipal,  // triggering principal
+      aNode, nsILoadInfo::SEC_ONLY_FOR_EXPLICIT_CONTENTSEC_CHECK,
+      nsIContentPolicy::TYPE_INTERNAL_IMAGE);
+
+  int16_t decision = nsIContentPolicy::ACCEPT;
+
+  rv = NS_CheckContentLoadPolicy(aURI, secCheckLoadInfo,
+                                 ""_ns,  // mime guess
+                                 &decision, GetContentPolicy());
+
+  return NS_SUCCEEDED(rv) && NS_CP_ACCEPTED(decision);
+}
+
+// static
+bool nsContentUtils::IsInPrivateBrowsing(Document* aDoc) {
+  if (!aDoc) {
+    return false;
+  }
+
+  nsCOMPtr<nsILoadGroup> loadGroup = aDoc->GetDocumentLoadGroup();
+  if (loadGroup) {
+    nsCOMPtr<nsIInterfaceRequestor> callbacks;
+    loadGroup->GetNotificationCallbacks(getter_AddRefs(callbacks));
+    if (callbacks) {
+      nsCOMPtr<nsILoadContext> loadContext = do_GetInterface(callbacks);
+      if (loadContext) {
+        return loadContext->UsePrivateBrowsing();
+      }
+    }
+  }
+
+  nsCOMPtr<nsIChannel> channel = aDoc->GetChannel();
+  return channel && NS_UsePrivateBrowsing(channel);
+}
+
+// static
+bool nsContentUtils::IsInPrivateBrowsing(nsILoadGroup* aLoadGroup) {
+  if (!aLoadGroup) {
+    return false;
+  }
+  bool isPrivate = false;
+  nsCOMPtr<nsIInterfaceRequestor> callbacks;
+  aLoadGroup->GetNotificationCallbacks(getter_AddRefs(callbacks));
+  if (callbacks) {
+    nsCOMPtr<nsILoadContext> loadContext = do_GetInterface(callbacks);
+    isPrivate = loadContext && loadContext->UsePrivateBrowsing();
+  }
+  return isPrivate;
+}
+
+// FIXME(emilio): This is (effectively) almost but not quite the same as
+// Document::ShouldLoadImages(), which one is right?
+bool nsContentUtils::DocumentInactiveForImageLoads(Document* aDocument) {
+  if (!aDocument) {
+    return false;
+  }
+  if (IsChromeDoc(aDocument) || aDocument->IsResourceDoc() ||
+      aDocument->IsStaticDocument()) {
+    return false;
+  }
+  nsCOMPtr<nsPIDOMWindowInner> win =
+      do_QueryInterface(aDocument->GetScopeObject());
+  return !win || !win->GetDocShell();
+}
+
+imgLoader* nsContentUtils::GetImgLoaderForDocument(Document* aDoc) {
+  NS_ENSURE_TRUE(!DocumentInactiveForImageLoads(aDoc), nullptr);
+
+  if (!aDoc) {
+    return imgLoader::NormalLoader();
+  }
+  bool isPrivate = IsInPrivateBrowsing(aDoc);
+  return isPrivate ? imgLoader::PrivateBrowsingLoader()
+                   : imgLoader::NormalLoader();
+}
+
+// static
+imgLoader* nsContentUtils::GetImgLoaderForChannel(nsIChannel* aChannel,
+                                                  Document* aContext) {
+  NS_ENSURE_TRUE(!DocumentInactiveForImageLoads(aContext), nullptr);
+
+  if (!aChannel) {
+    return imgLoader::NormalLoader();
+  }
+  nsCOMPtr<nsILoadContext> context;
+  NS_QueryNotificationCallbacks(aChannel, context);
+  return context && context->UsePrivateBrowsing()
+             ? imgLoader::PrivateBrowsingLoader()
+             : imgLoader::NormalLoader();
+}
+
+// static
+int32_t nsContentUtils::CORSModeToLoadImageFlags(mozilla::CORSMode aMode) {
+  switch (aMode) {
+    case CORS_ANONYMOUS:
+      return imgILoader::LOAD_CORS_ANONYMOUS;
+    case CORS_USE_CREDENTIALS:
+      return imgILoader::LOAD_CORS_USE_CREDENTIALS;
+    default:
+      return 0;
+  }
+}
+
+// static
+nsresult nsContentUtils::LoadImage(
+    nsIURI* aURI, nsINode* aContext, Document* aLoadingDocument,
+    nsIPrincipal* aLoadingPrincipal, uint64_t aRequestContextID,
+    nsIReferrerInfo* aReferrerInfo, imgINotificationObserver* aObserver,
+    int32_t aLoadFlags, const nsAString& initiatorType,
+    imgRequestProxy** aRequest, nsContentPolicyType aContentPolicyType,
+    bool aUseUrgentStartForChannel, bool aLinkPreload,
+    uint64_t aEarlyHintPreloaderId) {
+  MOZ_ASSERT(aURI, "Must have a URI");
+  MOZ_ASSERT(aContext, "Must have a context");
+  MOZ_ASSERT(aLoadingDocument, "Must have a document");
+  MOZ_ASSERT(aLoadingPrincipal, "Must have a principal");
+  MOZ_ASSERT(aRequest, "Null out param");
+
+  imgLoader* imgLoader = GetImgLoaderForDocument(aLoadingDocument);
+  if (!imgLoader) {
+    // nothing we can do here
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsILoadGroup> loadGroup = aLoadingDocument->GetDocumentLoadGroup();
+
+  nsIURI* documentURI = aLoadingDocument->GetDocumentURI();
+
+  NS_ASSERTION(loadGroup || aLoadingDocument->IsSVGGlyphsDocument(),
+               "Could not get loadgroup; onload may fire too early");
+
+  // XXXbz using "documentURI" for the initialDocumentURI is not quite
+  // right, but the best we can do here...
+  return imgLoader->LoadImage(aURI,               /* uri to load */
+                              documentURI,        /* initialDocumentURI */
+                              aReferrerInfo,      /* referrerInfo */
+                              aLoadingPrincipal,  /* loading principal */
+                              aRequestContextID,  /* request context ID */
+                              loadGroup,          /* loadgroup */
+                              aObserver,          /* imgINotificationObserver */
+                              aContext,           /* loading context */
+                              aLoadingDocument,   /* uniquification key */
+                              aLoadFlags,         /* load flags */
+                              nullptr,            /* cache key */
+                              aContentPolicyType, /* content policy type */
+                              initiatorType,      /* the load initiator */
+                              aUseUrgentStartForChannel, /* urgent-start flag */
+                              aLinkPreload, /* <link preload> initiator */
+                              aEarlyHintPreloaderId, aRequest);
+}
+
+// static
+already_AddRefed<imgIContainer> nsContentUtils::GetImageFromContent(
+    nsIImageLoadingContent* aContent, imgIRequest** aRequest) {
+  if (aRequest) {
+    *aRequest = nullptr;
+  }
+
+  NS_ENSURE_TRUE(aContent, nullptr);
+
+  nsCOMPtr<imgIRequest> imgRequest;
+  aContent->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
+                       getter_AddRefs(imgRequest));
+  if (!imgRequest) {
+    return nullptr;
+  }
+
+  nsCOMPtr<imgIContainer> imgContainer;
+  imgRequest->GetImage(getter_AddRefs(imgContainer));
+
+  if (!imgContainer) {
+    return nullptr;
+  }
+
+  if (aRequest) {
+    // If the consumer wants the request, verify it has actually loaded
+    // successfully.
+    uint32_t imgStatus;
+    imgRequest->GetImageStatus(&imgStatus);
+    if (imgStatus & imgIRequest::STATUS_FRAME_COMPLETE &&
+        !(imgStatus & imgIRequest::STATUS_ERROR)) {
+      imgRequest.swap(*aRequest);
+    }
+  }
+
+  return imgContainer.forget();
+}
+
+static bool IsLinkWithURI(const nsIContent& aContent) {
+  const auto* element = Element::FromNode(aContent);
+  if (!element || !element->IsLink()) {
+    return false;
+  }
+  nsCOMPtr<nsIURI> absURI = element->GetHrefURI();
+  return !!absURI;
+}
+
+static bool HasImageRequest(nsIContent& aContent) {
+  nsCOMPtr<nsIImageLoadingContent> imageContent(do_QueryInterface(&aContent));
+  if (!imageContent) {
+    return false;
+  }
+
+  nsCOMPtr<imgIRequest> imgRequest;
+  imageContent->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
+                           getter_AddRefs(imgRequest));
+
+  // XXXbz It may be draggable even if the request resulted in an error.  Why?
+  // Not sure; that's what the old nsContentAreaDragDrop/nsFrame code did.
+  return !!imgRequest;
+}
+
+static Maybe<bool> DraggableOverride(const nsIContent& aContent) {
+  if (auto* el = nsGenericHTMLElement::FromNode(aContent)) {
+    if (el->Draggable()) {
+      return Some(true);
+    }
+
+    if (el->AttrValueIs(kNameSpaceID_None, nsGkAtoms::draggable,
+                        nsGkAtoms::_false, eIgnoreCase)) {
+      return Some(false);
+    }
+  }
+  if (aContent.IsSVGElement()) {
+    return Some(false);
+  }
+  return Nothing();
+}
+
+// static
+bool nsContentUtils::ContentIsDraggable(nsIContent* aContent) {
+  MOZ_ASSERT(aContent);
+
+  if (auto draggable = DraggableOverride(*aContent)) {
+    return *draggable;
+  }
+
+  // special handling for content area image and link dragging
+  return HasImageRequest(*aContent) || IsLinkWithURI(*aContent);
+}
+
+// static
+bool nsContentUtils::IsDraggableImage(nsIContent* aContent) {
+  MOZ_ASSERT(aContent);
+  return HasImageRequest(*aContent) &&
+         DraggableOverride(*aContent).valueOr(true);
+}
+
+// static
+bool nsContentUtils::IsDraggableLink(const nsIContent* aContent) {
+  MOZ_ASSERT(aContent);
+  return IsLinkWithURI(*aContent) && DraggableOverride(*aContent).valueOr(true);
+}
+
+// static
+nsresult nsContentUtils::QNameChanged(mozilla::dom::NodeInfo* aNodeInfo,
+                                      nsAtom* aName,
+                                      mozilla::dom::NodeInfo** aResult) {
+  nsNodeInfoManager* niMgr = aNodeInfo->NodeInfoManager();
+
+  *aResult = niMgr
+                 ->GetNodeInfo(aName, nullptr, aNodeInfo->NamespaceID(),
+                               aNodeInfo->NodeType(), aNodeInfo->GetExtraName())
+                 .take();
+  return NS_OK;
+}
+
+static bool TestSitePerm(nsIPrincipal* aPrincipal, const nsACString& aType,
+                         uint32_t aPerm, bool aExactHostMatch) {
+  if (!aPrincipal) {
+    // We always deny (i.e. don't allow) the permission if we don't have a
+    // principal.
+    return aPerm != nsIPermissionManager::ALLOW_ACTION;
+  }
+
+  nsCOMPtr<nsIPermissionManager> permMgr =
+      components::PermissionManager::Service();
+  NS_ENSURE_TRUE(permMgr, false);
+
+  uint32_t perm;
+  nsresult rv;
+  if (aExactHostMatch) {
+    rv = permMgr->TestExactPermissionFromPrincipal(aPrincipal, aType, &perm);
+  } else {
+    rv = permMgr->TestPermissionFromPrincipal(aPrincipal, aType, &perm);
+  }
+  NS_ENSURE_SUCCESS(rv, false);
+
+  return perm == aPerm;
+}
+
+bool nsContentUtils::IsSitePermAllow(nsIPrincipal* aPrincipal,
+                                     const nsACString& aType) {
+  return TestSitePerm(aPrincipal, aType, nsIPermissionManager::ALLOW_ACTION,
+                      false);
+}
+
+bool nsContentUtils::IsSitePermDeny(nsIPrincipal* aPrincipal,
+                                    const nsACString& aType) {
+  return TestSitePerm(aPrincipal, aType, nsIPermissionManager::DENY_ACTION,
+                      false);
+}
+
+bool nsContentUtils::IsExactSitePermAllow(nsIPrincipal* aPrincipal,
+                                          const nsACString& aType) {
+  return TestSitePerm(aPrincipal, aType, nsIPermissionManager::ALLOW_ACTION,
+                      true);
+}
+
+bool nsContentUtils::IsExactSitePermDeny(nsIPrincipal* aPrincipal,
+                                         const nsACString& aType) {
+  return TestSitePerm(aPrincipal, aType, nsIPermissionManager::DENY_ACTION,
+                      true);
+}
+
+bool nsContentUtils::HasSitePerm(nsIPrincipal* aPrincipal,
+                                 const nsACString& aType) {
+  if (!aPrincipal) {
+    return false;
+  }
+
+  nsCOMPtr<nsIPermissionManager> permMgr =
+      components::PermissionManager::Service();
+  NS_ENSURE_TRUE(permMgr, false);
+
+  uint32_t perm;
+  nsresult rv = permMgr->TestPermissionFromPrincipal(aPrincipal, aType, &perm);
+  NS_ENSURE_SUCCESS(rv, false);
+
+  return perm != nsIPermissionManager::UNKNOWN_ACTION;
+}
+
+static const char* gEventNames[] = {"event"};
+static const char* gSVGEventNames[] = {"evt"};
+// for b/w compat, the first name to onerror is still 'event', even though it
+// is actually the error message
+static const char* gOnErrorNames[] = {"event", "source", "lineno", "colno",
+                                      "error"};
+
+// static
+void nsContentUtils::GetEventArgNames(int32_t aNameSpaceID, nsAtom* aEventName,
+                                      bool aIsForWindow, uint32_t* aArgCount,
+                                      const char*** aArgArray) {
+#define SET_EVENT_ARG_NAMES(names)               \
+  *aArgCount = sizeof(names) / sizeof(names[0]); \
+  *aArgArray = names;
+
+  // JSEventHandler is what does the arg magic for onerror, and it does
+  // not seem to take the namespace into account.  So we let onerror in all
+  // namespaces get the 3 arg names.
+  if (aEventName == nsGkAtoms::onerror && aIsForWindow) {
+    SET_EVENT_ARG_NAMES(gOnErrorNames);
+  } else if (aNameSpaceID == kNameSpaceID_SVG) {
+    SET_EVENT_ARG_NAMES(gSVGEventNames);
+  } else {
+    SET_EVENT_ARG_NAMES(gEventNames);
+  }
+}
+
+// Note: The list of content bundles in nsStringBundle.cpp should be updated
+// whenever entries are added or removed from this list.
+static const char* gPropertiesFiles[nsContentUtils::PropertiesFile_COUNT] = {
+    // Must line up with the enum values in |PropertiesFile| enum.
+    "chrome://global/locale/css.properties",
+    "chrome://global/locale/xul.properties",
+    "chrome://global/locale/layout_errors.properties",
+    "chrome://global/locale/layout/HtmlForm.properties",
+    "chrome://global/locale/printing.properties",
+    "chrome://global/locale/dom/dom.properties",
+    "chrome://global/locale/layout/htmlparser.properties",
+    "chrome://global/locale/svg/svg.properties",
+    "chrome://branding/locale/brand.properties",
+    "chrome://global/locale/commonDialogs.properties",
+    "chrome://global/locale/mathml/mathml.properties",
+    "chrome://global/locale/security/security.properties",
+    "chrome://necko/locale/necko.properties",
+    "resource://gre/res/locale/layout/HtmlForm.properties",
+    "resource://gre/res/locale/dom/dom.properties"};
+
+/* static */
+nsresult nsContentUtils::EnsureStringBundle(PropertiesFile aFile) {
+  MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread(),
+                        "Should not create bundles off main thread.");
+  if (!sStringBundles[aFile]) {
+    if (!sStringBundleService) {
+      nsresult rv =
+          CallGetService(NS_STRINGBUNDLE_CONTRACTID, &sStringBundleService);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+    RefPtr<nsIStringBundle> bundle;
+    MOZ_TRY(sStringBundleService->CreateBundle(gPropertiesFiles[aFile],
+                                               getter_AddRefs(bundle)));
+    sStringBundles[aFile] = bundle.forget();
+  }
+  return NS_OK;
+}
+
+/* static */
+void nsContentUtils::AsyncPrecreateStringBundles() {
+  // We only ever want to pre-create bundles in the parent process.
+  //
+  // All nsContentUtils bundles are shared between the parent and child
+  // precesses, and the shared memory regions that back them *must* be created
+  // in the parent, and then sent to all children.
+  //
+  // If we attempt to create a bundle in the child before its memory region is
+  // available, we need to create a temporary non-shared bundle, and later
+  // replace that with the shared memory copy. So attempting to pre-load in the
+  // child is wasteful and unnecessary.
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  for (uint32_t bundleIndex = 0; bundleIndex < PropertiesFile_COUNT;
+       ++bundleIndex) {
+    nsresult rv = NS_DispatchToCurrentThreadQueue(
+        NS_NewRunnableFunction("AsyncPrecreateStringBundles",
+                               [bundleIndex]() {
+                                 PropertiesFile file =
+                                     static_cast<PropertiesFile>(bundleIndex);
+                                 EnsureStringBundle(file);
+                                 nsIStringBundle* bundle = sStringBundles[file];
+                                 bundle->AsyncPreload();
+                               }),
+        EventQueuePriority::Idle);
+    Unused << NS_WARN_IF(NS_FAILED(rv));
+  }
+}
+
+/* static */
+bool nsContentUtils::SpoofLocaleEnglish() {
+  // 0 - will prompt
+  // 1 - don't spoof
+  // 2 - spoof
+  return StaticPrefs::privacy_spoof_english() == 2;
+}
+
+static nsContentUtils::PropertiesFile GetMaybeSpoofedPropertiesFile(
+    nsContentUtils::PropertiesFile aFile, const char* aKey,
+    Document* aDocument) {
+  // When we spoof English, use en-US properties in strings that are accessible
+  // by content.
+  bool spoofLocale = nsContentUtils::SpoofLocaleEnglish() &&
+                     (!aDocument || !aDocument->AllowsL10n());
+  if (spoofLocale) {
+    switch (aFile) {
+      case nsContentUtils::eFORMS_PROPERTIES:
+        return nsContentUtils::eFORMS_PROPERTIES_en_US;
+      case nsContentUtils::eDOM_PROPERTIES:
+        return nsContentUtils::eDOM_PROPERTIES_en_US;
+      default:
+        break;
+    }
+  }
+  return aFile;
+}
+
+/* static */
+nsresult nsContentUtils::GetMaybeLocalizedString(PropertiesFile aFile,
+                                                 const char* aKey,
+                                                 Document* aDocument,
+                                                 nsAString& aResult) {
+  return GetLocalizedString(
+      GetMaybeSpoofedPropertiesFile(aFile, aKey, aDocument), aKey, aResult);
+}
+
+/* static */
+nsresult nsContentUtils::GetLocalizedString(PropertiesFile aFile,
+                                            const char* aKey,
+                                            nsAString& aResult) {
+  return FormatLocalizedString(aFile, aKey, {}, aResult);
+}
+
+/* static */
+nsresult nsContentUtils::FormatMaybeLocalizedString(
+    PropertiesFile aFile, const char* aKey, Document* aDocument,
+    const nsTArray<nsString>& aParams, nsAString& aResult) {
+  return FormatLocalizedString(
+      GetMaybeSpoofedPropertiesFile(aFile, aKey, aDocument), aKey, aParams,
+      aResult);
+}
+
+class FormatLocalizedStringRunnable final : public WorkerMainThreadRunnable {
+ public:
+  FormatLocalizedStringRunnable(WorkerPrivate* aWorkerPrivate,
+                                nsContentUtils::PropertiesFile aFile,
+                                const char* aKey,
+                                const nsTArray<nsString>& aParams,
+                                nsAString& aLocalizedString)
+      : WorkerMainThreadRunnable(aWorkerPrivate,
+                                 "FormatLocalizedStringRunnable"_ns),
+        mFile(aFile),
+        mKey(aKey),
+        mParams(aParams),
+        mLocalizedString(aLocalizedString) {
+    MOZ_ASSERT(aWorkerPrivate);
+    aWorkerPrivate->AssertIsOnWorkerThread();
+  }
+
+  bool MainThreadRun() override {
+    AssertIsOnMainThread();
+
+    mResult = nsContentUtils::FormatLocalizedString(mFile, mKey, mParams,
+                                                    mLocalizedString);
+    Unused << NS_WARN_IF(NS_FAILED(mResult));
+    return true;
+  }
+
+  nsresult GetResult() const { return mResult; }
+
+ private:
+  const nsContentUtils::PropertiesFile mFile;
+  const char* mKey;
+  const nsTArray<nsString>& mParams;
+  nsresult mResult = NS_ERROR_FAILURE;
+  nsAString& mLocalizedString;
+};
+
+/* static */
+nsresult nsContentUtils::FormatLocalizedString(
+    PropertiesFile aFile, const char* aKey, const nsTArray<nsString>& aParams,
+    nsAString& aResult) {
+  if (!NS_IsMainThread()) {
+    // nsIStringBundle is thread-safe but its creation is not, and in particular
+    // we don't create and store nsIStringBundle objects in a thread-safe way.
+    //
+    // TODO(emilio): Maybe if we already have the right bundle created we could
+    // just call into it, but we should make sure that Shutdown() doesn't get
+    // called on the main thread when that happens which is a bit tricky to
+    // prove?
+    WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
+    if (NS_WARN_IF(!workerPrivate)) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    auto runnable = MakeRefPtr<FormatLocalizedStringRunnable>(
+        workerPrivate, aFile, aKey, aParams, aResult);
+
+    runnable->Dispatch(Canceling, IgnoreErrors());
+    return runnable->GetResult();
+  }
+
+  MOZ_TRY(EnsureStringBundle(aFile));
+  nsIStringBundle* bundle = sStringBundles[aFile];
+  if (aParams.IsEmpty()) {
+    return bundle->GetStringFromName(aKey, aResult);
+  }
+  return bundle->FormatStringFromName(aKey, aParams, aResult);
+}
+
+/* static */
+void nsContentUtils::LogSimpleConsoleError(const nsAString& aErrorText,
+                                           const nsACString& aCategory,
+                                           bool aFromPrivateWindow,
+                                           bool aFromChromeContext,
+                                           uint32_t aErrorFlags) {
+  nsCOMPtr<nsIScriptError> scriptError =
+      do_CreateInstance(NS_SCRIPTERROR_CONTRACTID);
+  if (scriptError) {
+    nsCOMPtr<nsIConsoleService> console =
+        do_GetService(NS_CONSOLESERVICE_CONTRACTID);
+    if (console && NS_SUCCEEDED(scriptError->Init(
+                       aErrorText, u""_ns, u""_ns, 0, 0, aErrorFlags, aCategory,
+                       aFromPrivateWindow, aFromChromeContext))) {
+      console->LogMessage(scriptError);
+    }
+  }
+}
+
+/* static */
+nsresult nsContentUtils::ReportToConsole(
+    uint32_t aErrorFlags, const nsACString& aCategory,
+    const Document* aDocument, PropertiesFile aFile, const char* aMessageName,
+    const nsTArray<nsString>& aParams, nsIURI* aURI,
+    const nsString& aSourceLine, uint32_t aLineNumber, uint32_t aColumnNumber) {
+  nsresult rv;
+  nsAutoString errorText;
+  if (!aParams.IsEmpty()) {
+    rv = FormatLocalizedString(aFile, aMessageName, aParams, errorText);
+  } else {
+    rv = GetLocalizedString(aFile, aMessageName, errorText);
+  }
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return ReportToConsoleNonLocalized(errorText, aErrorFlags, aCategory,
+                                     aDocument, aURI, aSourceLine, aLineNumber,
+                                     aColumnNumber);
+}
+
+/* static */
+void nsContentUtils::ReportEmptyGetElementByIdArg(const Document* aDoc) {
+  ReportToConsole(nsIScriptError::warningFlag, "DOM"_ns, aDoc,
+                  nsContentUtils::eDOM_PROPERTIES, "EmptyGetElementByIdParam");
+}
+
+/* static */
+nsresult nsContentUtils::ReportToConsoleNonLocalized(
+    const nsAString& aErrorText, uint32_t aErrorFlags,
+    const nsACString& aCategory, const Document* aDocument, nsIURI* aURI,
+    const nsString& aSourceLine, uint32_t aLineNumber, uint32_t aColumnNumber,
+    MissingErrorLocationMode aLocationMode) {
+  uint64_t innerWindowID = 0;
+  if (aDocument) {
+    if (!aURI) {
+      aURI = aDocument->GetDocumentURI();
+    }
+    innerWindowID = aDocument->InnerWindowID();
+  }
+
+  return ReportToConsoleByWindowID(aErrorText, aErrorFlags, aCategory,
+                                   innerWindowID, aURI, aSourceLine,
+                                   aLineNumber, aColumnNumber, aLocationMode);
+}
+
+/* static */
+nsresult nsContentUtils::ReportToConsoleByWindowID(
+    const nsAString& aErrorText, uint32_t aErrorFlags,
+    const nsACString& aCategory, uint64_t aInnerWindowID, nsIURI* aURI,
+    const nsString& aSourceLine, uint32_t aLineNumber, uint32_t aColumnNumber,
+    MissingErrorLocationMode aLocationMode) {
+  nsresult rv;
+  if (!sConsoleService) {  // only need to bother null-checking here
+    rv = CallGetService(NS_CONSOLESERVICE_CONTRACTID, &sConsoleService);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  nsAutoString spec;
+  if (!aLineNumber && aLocationMode == eUSE_CALLING_LOCATION) {
+    JSContext* cx = GetCurrentJSContext();
+    if (cx) {
+      nsJSUtils::GetCallingLocation(cx, spec, &aLineNumber, &aColumnNumber);
+    }
+  }
+
+  nsCOMPtr<nsIScriptError> errorObject =
+      do_CreateInstance(NS_SCRIPTERROR_CONTRACTID, &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (!spec.IsEmpty()) {
+    rv = errorObject->InitWithWindowID(aErrorText,
+                                       spec,  // file name
+                                       aSourceLine, aLineNumber, aColumnNumber,
+                                       aErrorFlags, aCategory, aInnerWindowID);
+  } else {
+    rv = errorObject->InitWithSourceURI(aErrorText, aURI, aSourceLine,
+                                        aLineNumber, aColumnNumber, aErrorFlags,
+                                        aCategory, aInnerWindowID);
+  }
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return sConsoleService->LogMessage(errorObject);
+}
+
+void nsContentUtils::LogMessageToConsole(const char* aMsg) {
+  if (!sConsoleService) {  // only need to bother null-checking here
+    CallGetService(NS_CONSOLESERVICE_CONTRACTID, &sConsoleService);
+    if (!sConsoleService) {
+      return;
+    }
+  }
+  sConsoleService->LogStringMessage(NS_ConvertUTF8toUTF16(aMsg).get());
+}
+
+bool nsContentUtils::IsChromeDoc(const Document* aDocument) {
+  return aDocument && aDocument->NodePrincipal() == sSystemPrincipal;
+}
+
+bool nsContentUtils::IsChildOfSameType(Document* aDoc) {
+  if (BrowsingContext* bc = aDoc->GetBrowsingContext()) {
+    return bc->GetParent();
+  }
+  return false;
+}
+
+bool nsContentUtils::IsPlainTextType(const nsACString& aContentType) {
+  // NOTE: if you add a type here, add it to the CONTENTDLF_CATEGORIES
+  // define in nsContentDLF.h as well.
+  return aContentType.EqualsLiteral(TEXT_PLAIN) ||
+         aContentType.EqualsLiteral(TEXT_CSS) ||
+         aContentType.EqualsLiteral(TEXT_CACHE_MANIFEST) ||
+         aContentType.EqualsLiteral(TEXT_VTT) ||
+         aContentType.EqualsLiteral(APPLICATION_JAVASCRIPT) ||
+         aContentType.EqualsLiteral(APPLICATION_XJAVASCRIPT) ||
+         aContentType.EqualsLiteral(TEXT_ECMASCRIPT) ||
+         aContentType.EqualsLiteral(APPLICATION_ECMASCRIPT) ||
+         aContentType.EqualsLiteral(TEXT_JAVASCRIPT) ||
+         aContentType.EqualsLiteral(APPLICATION_JSON) ||
+         aContentType.EqualsLiteral(TEXT_JSON);
+}
+
+bool nsContentUtils::IsUtf8OnlyPlainTextType(const nsACString& aContentType) {
+  // NOTE: This must be a subset of the list in IsPlainTextType().
+  return aContentType.EqualsLiteral(TEXT_CACHE_MANIFEST) ||
+         aContentType.EqualsLiteral(APPLICATION_JSON) ||
+         aContentType.EqualsLiteral(TEXT_JSON) ||
+         aContentType.EqualsLiteral(TEXT_VTT);
+}
+
+bool nsContentUtils::IsInChromeDocshell(const Document* aDocument) {
+  return aDocument && aDocument->IsInChromeDocShell();
+}
+
+// static
+nsIContentPolicy* nsContentUtils::GetContentPolicy() {
+  if (!sTriedToGetContentPolicy) {
+    CallGetService(NS_CONTENTPOLICY_CONTRACTID, &sContentPolicyService);
+    // It's OK to not have a content policy service
+    sTriedToGetContentPolicy = true;
+  }
+
+  return sContentPolicyService;
+}
+
+// static
+bool nsContentUtils::IsEventAttributeName(nsAtom* aName, int32_t aType) {
+  const char16_t* name = aName->GetUTF16String();
+  if (name[0] != 'o' || name[1] != 'n') {
+    return false;
+  }
+
+  EventNameMapping mapping;
+  return (sAtomEventTable->Get(aName, &mapping) && mapping.mType & aType);
+}
+
+// static
+EventMessage nsContentUtils::GetEventMessage(nsAtom* aName) {
+  MOZ_ASSERT(NS_IsMainThread(), "sAtomEventTable is not threadsafe");
+  if (aName) {
+    EventNameMapping mapping;
+    if (sAtomEventTable->Get(aName, &mapping)) {
+      return mapping.mMessage;
+    }
+  }
+
+  return eUnidentifiedEvent;
+}
+
+// static
+mozilla::EventClassID nsContentUtils::GetEventClassID(const nsAString& aName) {
+  EventNameMapping mapping;
+  if (sStringEventTable->Get(aName, &mapping)) return mapping.mEventClassID;
+
+  return eBasicEventClass;
+}
+
+nsAtom* nsContentUtils::GetEventMessageAndAtom(
+    const nsAString& aName, mozilla::EventClassID aEventClassID,
+    EventMessage* aEventMessage) {
+  MOZ_ASSERT(NS_IsMainThread(), "Our hashtables are not threadsafe");
+  EventNameMapping mapping;
+  if (sStringEventTable->Get(aName, &mapping)) {
+    *aEventMessage = mapping.mEventClassID == aEventClassID
+                         ? mapping.mMessage
+                         : eUnidentifiedEvent;
+    return mapping.mAtom;
+  }
+
+  // If we have cached lots of user defined event names, clear some of them.
+  if (sUserDefinedEvents->Length() > 127) {
+    while (sUserDefinedEvents->Length() > 64) {
+      nsAtom* first = sUserDefinedEvents->ElementAt(0);
+      sStringEventTable->Remove(Substring(nsDependentAtomString(first), 2));
+      sUserDefinedEvents->RemoveElementAt(0);
+    }
+  }
+
+  *aEventMessage = eUnidentifiedEvent;
+  RefPtr<nsAtom> atom = NS_AtomizeMainThread(u"on"_ns + aName);
+  sUserDefinedEvents->AppendElement(atom);
+  mapping.mAtom = atom;
+  mapping.mMessage = eUnidentifiedEvent;
+  mapping.mType = EventNameType_None;
+  mapping.mEventClassID = eBasicEventClass;
+  // This is a slow hashtable call, but at least we cache the result for the
+  // following calls. Because GetEventMessageAndAtomForListener utilizes
+  // sStringEventTable, it needs to know in which cases sStringEventTable
+  // doesn't contain the information it needs so that it can use
+  // sAtomEventTable instead.
+  mapping.mMaybeSpecialSVGorSMILEvent =
+      GetEventMessage(atom) != eUnidentifiedEvent;
+  sStringEventTable->InsertOrUpdate(aName, mapping);
+  return mapping.mAtom;
+}
+
+// static
+EventMessage nsContentUtils::GetEventMessageAndAtomForListener(
+    const nsAString& aName, nsAtom** aOnName) {
+  MOZ_ASSERT(NS_IsMainThread(), "Our hashtables are not threadsafe");
+
+  // Because of SVG/SMIL sStringEventTable contains a subset of the event names
+  // comparing to the sAtomEventTable. However, usually sStringEventTable
+  // contains the information we need, so in order to reduce hashtable
+  // lookups, start from it.
+  EventNameMapping mapping;
+  EventMessage msg = eUnidentifiedEvent;
+  RefPtr<nsAtom> atom;
+  if (sStringEventTable->Get(aName, &mapping)) {
+    if (mapping.mMaybeSpecialSVGorSMILEvent) {
+      // Try the atom version so that we should get the right message for
+      // SVG/SMIL.
+      atom = NS_AtomizeMainThread(u"on"_ns + aName);
+      msg = GetEventMessage(atom);
+    } else {
+      atom = mapping.mAtom;
+      msg = mapping.mMessage;
+    }
+    atom.forget(aOnName);
+    return msg;
+  }
+
+  // GetEventMessageAndAtom will cache the event type for the future usage...
+  GetEventMessageAndAtom(aName, eBasicEventClass, &msg);
+
+  // ...and then call this method recursively to get the message and atom from
+  // now updated sStringEventTable.
+  return GetEventMessageAndAtomForListener(aName, aOnName);
+}
+
+static nsresult GetEventAndTarget(Document* aDoc, nsISupports* aTarget,
+                                  const nsAString& aEventName,
+                                  CanBubble aCanBubble, Cancelable aCancelable,
+                                  Composed aComposed, Trusted aTrusted,
+                                  Event** aEvent, EventTarget** aTargetOut) {
+  nsCOMPtr<EventTarget> target(do_QueryInterface(aTarget));
+  NS_ENSURE_TRUE(aDoc && target, NS_ERROR_INVALID_ARG);
+
+  ErrorResult err;
+  RefPtr<Event> event =
+      aDoc->CreateEvent(u"Events"_ns, CallerType::System, err);
+  if (NS_WARN_IF(err.Failed())) {
+    return err.StealNSResult();
+  }
+
+  event->InitEvent(aEventName, aCanBubble, aCancelable, aComposed);
+  event->SetTrusted(aTrusted == Trusted::eYes);
+
+  event->SetTarget(target);
+
+  event.forget(aEvent);
+  target.forget(aTargetOut);
+  return NS_OK;
+}
+
+// static
+nsresult nsContentUtils::DispatchTrustedEvent(
+    Document* aDoc, nsISupports* aTarget, const nsAString& aEventName,
+    CanBubble aCanBubble, Cancelable aCancelable, Composed aComposed,
+    bool* aDefaultAction) {
+  MOZ_ASSERT(!aEventName.EqualsLiteral("input") &&
+                 !aEventName.EqualsLiteral("beforeinput"),
+             "Use DispatchInputEvent() instead");
+  return DispatchEvent(aDoc, aTarget, aEventName, aCanBubble, aCancelable,
+                       aComposed, Trusted::eYes, aDefaultAction);
+}
+
+// static
+nsresult nsContentUtils::DispatchUntrustedEvent(
+    Document* aDoc, nsISupports* aTarget, const nsAString& aEventName,
+    CanBubble aCanBubble, Cancelable aCancelable, bool* aDefaultAction) {
+  return DispatchEvent(aDoc, aTarget, aEventName, aCanBubble, aCancelable,
+                       Composed::eDefault, Trusted::eNo, aDefaultAction);
+}
+
+// static
+nsresult nsContentUtils::DispatchEvent(Document* aDoc, nsISupports* aTarget,
+                                       const nsAString& aEventName,
+                                       CanBubble aCanBubble,
+                                       Cancelable aCancelable,
+                                       Composed aComposed, Trusted aTrusted,
+                                       bool* aDefaultAction,
+                                       ChromeOnlyDispatch aOnlyChromeDispatch) {
+  RefPtr<Event> event;
+  nsCOMPtr<EventTarget> target;
+  nsresult rv = GetEventAndTarget(
+      aDoc, aTarget, aEventName, aCanBubble, aCancelable, aComposed, aTrusted,
+      getter_AddRefs(event), getter_AddRefs(target));
+  NS_ENSURE_SUCCESS(rv, rv);
+  event->WidgetEventPtr()->mFlags.mOnlyChromeDispatch =
+      aOnlyChromeDispatch == ChromeOnlyDispatch::eYes;
+
+  ErrorResult err;
+  bool doDefault = target->DispatchEvent(*event, CallerType::System, err);
+  if (aDefaultAction) {
+    *aDefaultAction = doDefault;
+  }
+  return err.StealNSResult();
+}
+
+// static
+nsresult nsContentUtils::DispatchEvent(Document* aDoc, nsISupports* aTarget,
+                                       WidgetEvent& aEvent,
+                                       EventMessage aEventMessage,
+                                       CanBubble aCanBubble,
+                                       Cancelable aCancelable, Trusted aTrusted,
+                                       bool* aDefaultAction,
+                                       ChromeOnlyDispatch aOnlyChromeDispatch) {
+  MOZ_ASSERT_IF(aOnlyChromeDispatch == ChromeOnlyDispatch::eYes,
+                aTrusted == Trusted::eYes);
+
+  nsCOMPtr<EventTarget> target(do_QueryInterface(aTarget));
+
+  aEvent.mSpecifiedEventType = GetEventTypeFromMessage(aEventMessage);
+  aEvent.SetDefaultComposed();
+  aEvent.SetDefaultComposedInNativeAnonymousContent();
+
+  aEvent.mFlags.mBubbles = aCanBubble == CanBubble::eYes;
+  aEvent.mFlags.mCancelable = aCancelable == Cancelable::eYes;
+  aEvent.mFlags.mOnlyChromeDispatch =
+      aOnlyChromeDispatch == ChromeOnlyDispatch::eYes;
+
+  aEvent.mTarget = target;
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  nsresult rv = EventDispatcher::DispatchDOMEvent(target, &aEvent, nullptr,
+                                                  nullptr, &status);
+  if (aDefaultAction) {
+    *aDefaultAction = (status != nsEventStatus_eConsumeNoDefault);
+  }
+  return rv;
+}
+
+// static
+nsresult nsContentUtils::DispatchInputEvent(Element* aEventTarget) {
+  return DispatchInputEvent(aEventTarget, mozilla::eEditorInput,
+                            mozilla::EditorInputType::eUnknown, nullptr,
+                            InputEventOptions());
+}
+
+// static
+nsresult nsContentUtils::DispatchInputEvent(
+    Element* aEventTargetElement, EventMessage aEventMessage,
+    EditorInputType aEditorInputType, EditorBase* aEditorBase,
+    InputEventOptions&& aOptions, nsEventStatus* aEventStatus /* = nullptr */) {
+  MOZ_ASSERT(aEventMessage == eEditorInput ||
+             aEventMessage == eEditorBeforeInput);
+
+  if (NS_WARN_IF(!aEventTargetElement)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // If this is called from editor, the instance should be set to aEditorBase.
+  // Otherwise, we need to look for an editor for aEventTargetElement.
+  // However, we don't need to do it for HTMLEditor since nobody shouldn't
+  // dispatch "beforeinput" nor "input" event for HTMLEditor except HTMLEditor
+  // itself.
+  bool useInputEvent = false;
+  if (aEditorBase) {
+    useInputEvent = true;
+  } else if (HTMLTextAreaElement* textAreaElement =
+                 HTMLTextAreaElement::FromNode(aEventTargetElement)) {
+    aEditorBase = textAreaElement->GetTextEditorWithoutCreation();
+    useInputEvent = true;
+  } else if (HTMLInputElement* inputElement =
+                 HTMLInputElement::FromNode(aEventTargetElement)) {
+    if (inputElement->IsInputEventTarget()) {
+      aEditorBase = inputElement->GetTextEditorWithoutCreation();
+      useInputEvent = true;
+    }
+  }
+#ifdef DEBUG
+  else {
+    MOZ_ASSERT(!aEventTargetElement->IsTextControlElement(),
+               "The event target may have editor, but we've not known it yet.");
+  }
+#endif  // #ifdef DEBUG
+
+  if (!useInputEvent) {
+    MOZ_ASSERT(aEventMessage == eEditorInput);
+    MOZ_ASSERT(aEditorInputType == EditorInputType::eUnknown);
+    MOZ_ASSERT(!aOptions.mNeverCancelable);
+    // Dispatch "input" event with Event instance.
+    WidgetEvent widgetEvent(true, eUnidentifiedEvent);
+    widgetEvent.mSpecifiedEventType = nsGkAtoms::oninput;
+    widgetEvent.mFlags.mCancelable = false;
+    widgetEvent.mFlags.mComposed = true;
+    return AsyncEventDispatcher::RunDOMEventWhenSafe(*aEventTargetElement,
+                                                     widgetEvent, aEventStatus);
+  }
+
+  MOZ_ASSERT_IF(aEventMessage != eEditorBeforeInput,
+                !aOptions.mNeverCancelable);
+  MOZ_ASSERT_IF(
+      aEventMessage == eEditorBeforeInput && aOptions.mNeverCancelable,
+      aEditorInputType == EditorInputType::eInsertReplacementText);
+
+  nsCOMPtr<nsIWidget> widget;
+  if (aEditorBase) {
+    widget = aEditorBase->GetWidget();
+    if (NS_WARN_IF(!widget)) {
+      return NS_ERROR_FAILURE;
+    }
+  } else {
+    Document* document = aEventTargetElement->OwnerDoc();
+    if (NS_WARN_IF(!document)) {
+      return NS_ERROR_FAILURE;
+    }
+    // If we're running xpcshell tests, we fail to get presShell here.
+    // Even in such case, we need to dispatch "input" event without widget.
+    PresShell* presShell = document->GetPresShell();
+    if (presShell) {
+      nsPresContext* presContext = presShell->GetPresContext();
+      if (NS_WARN_IF(!presContext)) {
+        return NS_ERROR_FAILURE;
+      }
+      widget = presContext->GetRootWidget();
+      if (NS_WARN_IF(!widget)) {
+        return NS_ERROR_FAILURE;
+      }
+    }
+  }
+
+  // Dispatch "input" event with InputEvent instance.
+  InternalEditorInputEvent inputEvent(true, aEventMessage, widget);
+
+  inputEvent.mFlags.mCancelable =
+      !aOptions.mNeverCancelable && aEventMessage == eEditorBeforeInput &&
+      IsCancelableBeforeInputEvent(aEditorInputType);
+  MOZ_ASSERT(!inputEvent.mFlags.mCancelable || aEventStatus);
+
+  // If there is an editor, set isComposing to true when it has composition.
+  // Note that EditorBase::IsIMEComposing() may return false even when we
+  // need to set it to true.
+  // Otherwise, i.e., editor hasn't been created for the element yet,
+  // we should set isComposing to false since the element can never has
+  // composition without editor.
+  inputEvent.mIsComposing = aEditorBase && aEditorBase->GetComposition();
+
+  if (!aEditorBase || aEditorBase->IsTextEditor()) {
+    if (IsDataAvailableOnTextEditor(aEditorInputType)) {
+      inputEvent.mData = std::move(aOptions.mData);
+      MOZ_ASSERT(!inputEvent.mData.IsVoid(),
+                 "inputEvent.mData shouldn't be void");
+    }
+#ifdef DEBUG
+    else {
+      MOZ_ASSERT(inputEvent.mData.IsVoid(), "inputEvent.mData should be void");
+    }
+#endif  // #ifdef DEBUG
+    MOZ_ASSERT(
+        aOptions.mTargetRanges.IsEmpty(),
+        "Target ranges for <input> and <textarea> should always be empty");
+  } else {
+    MOZ_ASSERT(aEditorBase->IsHTMLEditor());
+    if (IsDataAvailableOnHTMLEditor(aEditorInputType)) {
+      inputEvent.mData = std::move(aOptions.mData);
+      MOZ_ASSERT(!inputEvent.mData.IsVoid(),
+                 "inputEvent.mData shouldn't be void");
+    } else {
+      MOZ_ASSERT(inputEvent.mData.IsVoid(), "inputEvent.mData should be void");
+      if (IsDataTransferAvailableOnHTMLEditor(aEditorInputType)) {
+        inputEvent.mDataTransfer = std::move(aOptions.mDataTransfer);
+        MOZ_ASSERT(inputEvent.mDataTransfer,
+                   "inputEvent.mDataTransfer shouldn't be nullptr");
+        MOZ_ASSERT(inputEvent.mDataTransfer->IsReadOnly(),
+                   "inputEvent.mDataTransfer should be read only");
+      }
+#ifdef DEBUG
+      else {
+        MOZ_ASSERT(!inputEvent.mDataTransfer,
+                   "inputEvent.mDataTransfer should be nullptr");
+      }
+#endif  // #ifdef DEBUG
+    }
+    if (aEventMessage == eEditorBeforeInput &&
+        MayHaveTargetRangesOnHTMLEditor(aEditorInputType)) {
+      inputEvent.mTargetRanges = std::move(aOptions.mTargetRanges);
+    }
+#ifdef DEBUG
+    else {
+      MOZ_ASSERT(aOptions.mTargetRanges.IsEmpty(),
+                 "Target ranges shouldn't be set for the dispatching event");
+    }
+#endif  // #ifdef DEBUG
+  }
+
+  inputEvent.mInputType = aEditorInputType;
+
+  // If we cannot dispatch an event right now, we cannot make it cancelable.
+  if (!nsContentUtils::IsSafeToRunScript()) {
+    NS_ASSERTION(
+        !inputEvent.mFlags.mCancelable,
+        "Cancelable beforeinput event dispatcher should run when it's safe");
+    inputEvent.mFlags.mCancelable = false;
+  }
+  return AsyncEventDispatcher::RunDOMEventWhenSafe(*aEventTargetElement,
+                                                   inputEvent, aEventStatus);
+}
+
+nsresult nsContentUtils::DispatchChromeEvent(
+    Document* aDoc, nsISupports* aTarget, const nsAString& aEventName,
+    CanBubble aCanBubble, Cancelable aCancelable, bool* aDefaultAction) {
+  RefPtr<Event> event;
+  nsCOMPtr<EventTarget> target;
+  nsresult rv = GetEventAndTarget(
+      aDoc, aTarget, aEventName, aCanBubble, aCancelable, Composed::eDefault,
+      Trusted::eYes, getter_AddRefs(event), getter_AddRefs(target));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  NS_ASSERTION(aDoc, "GetEventAndTarget lied?");
+  if (!aDoc->GetWindow()) return NS_ERROR_INVALID_ARG;
+
+  EventTarget* piTarget = aDoc->GetWindow()->GetParentTarget();
+  if (!piTarget) return NS_ERROR_INVALID_ARG;
+
+  ErrorResult err;
+  bool defaultActionEnabled =
+      piTarget->DispatchEvent(*event, CallerType::System, err);
+  if (aDefaultAction) {
+    *aDefaultAction = defaultActionEnabled;
+  }
+  return err.StealNSResult();
+}
+
+void nsContentUtils::RequestFrameFocus(Element& aFrameElement, bool aCanRaise,
+                                       CallerType aCallerType) {
+  RefPtr<Element> target = &aFrameElement;
+  bool defaultAction = true;
+  if (aCanRaise) {
+    DispatchEventOnlyToChrome(target->OwnerDoc(), target,
+                              u"framefocusrequested"_ns, CanBubble::eYes,
+                              Cancelable::eYes, &defaultAction);
+  }
+  if (!defaultAction) {
+    return;
+  }
+
+  RefPtr<nsFocusManager> fm = nsFocusManager::GetFocusManager();
+  if (!fm) {
+    return;
+  }
+
+  uint32_t flags = nsIFocusManager::FLAG_NOSCROLL;
+  if (aCanRaise) {
+    flags |= nsIFocusManager::FLAG_RAISE;
+  }
+
+  if (aCallerType == CallerType::NonSystem) {
+    flags |= nsIFocusManager::FLAG_NONSYSTEMCALLER;
+  }
+
+  fm->SetFocus(target, flags);
+}
+
+nsresult nsContentUtils::DispatchEventOnlyToChrome(
+    Document* aDoc, nsISupports* aTarget, const nsAString& aEventName,
+    CanBubble aCanBubble, Cancelable aCancelable, Composed aComposed,
+    bool* aDefaultAction) {
+  return DispatchEvent(aDoc, aTarget, aEventName, aCanBubble, aCancelable,
+                       aComposed, Trusted::eYes, aDefaultAction,
+                       ChromeOnlyDispatch::eYes);
+}
+
+/* static */
+Element* nsContentUtils::MatchElementId(nsIContent* aContent,
+                                        const nsAtom* aId) {
+  for (nsIContent* cur = aContent; cur; cur = cur->GetNextNode(aContent)) {
+    if (aId == cur->GetID()) {
+      return cur->AsElement();
+    }
+  }
+
+  return nullptr;
+}
+
+/* static */
+Element* nsContentUtils::MatchElementId(nsIContent* aContent,
+                                        const nsAString& aId) {
+  MOZ_ASSERT(!aId.IsEmpty(), "Will match random elements");
+
+  // ID attrs are generally stored as atoms, so just atomize this up front
+  RefPtr<nsAtom> id(NS_Atomize(aId));
+  if (!id) {
+    // OOM, so just bail
+    return nullptr;
+  }
+
+  return MatchElementId(aContent, id);
+}
+
+/* static */
+void nsContentUtils::RegisterShutdownObserver(nsIObserver* aObserver) {
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->AddObserver(aObserver, NS_XPCOM_SHUTDOWN_OBSERVER_ID,
+                                 false);
+  }
+}
+
+/* static */
+void nsContentUtils::UnregisterShutdownObserver(nsIObserver* aObserver) {
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->RemoveObserver(aObserver, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
+  }
+}
+
+/* static */
+bool nsContentUtils::HasNonEmptyAttr(const nsIContent* aContent,
+                                     int32_t aNameSpaceID, nsAtom* aName) {
+  static AttrArray::AttrValuesArray strings[] = {nsGkAtoms::_empty, nullptr};
+  return aContent->IsElement() &&
+         aContent->AsElement()->FindAttrValueIn(aNameSpaceID, aName, strings,
+                                                eCaseMatters) ==
+             AttrArray::ATTR_VALUE_NO_MATCH;
+}
+
+/* static */
+bool nsContentUtils::HasMutationListeners(nsINode* aNode, uint32_t aType,
+                                          nsINode* aTargetForSubtreeModified) {
+  Document* doc = aNode->OwnerDoc();
+
+  // global object will be null for documents that don't have windows.
+  nsPIDOMWindowInner* window = doc->GetInnerWindow();
+  // This relies on EventListenerManager::AddEventListener, which sets
+  // all mutation bits when there is a listener for DOMSubtreeModified event.
+  if (window && !window->HasMutationListeners(aType)) {
+    return false;
+  }
+
+  if (aNode->ChromeOnlyAccess() || aNode->IsInShadowTree()) {
+    return false;
+  }
+
+  doc->MayDispatchMutationEvent(aTargetForSubtreeModified);
+
+  // If we have a window, we can check it for mutation listeners now.
+  if (aNode->IsInUncomposedDoc()) {
+    nsCOMPtr<EventTarget> piTarget(do_QueryInterface(window));
+    if (piTarget) {
+      EventListenerManager* manager = piTarget->GetExistingListenerManager();
+      if (manager && manager->HasMutationListeners()) {
+        return true;
+      }
+    }
+  }
+
+  // If we have a window, we know a mutation listener is registered, but it
+  // might not be in our chain.  If we don't have a window, we might have a
+  // mutation listener.  Check quickly to see.
+  while (aNode) {
+    EventListenerManager* manager = aNode->GetExistingListenerManager();
+    if (manager && manager->HasMutationListeners()) {
+      return true;
+    }
+
+    aNode = aNode->GetParentNode();
+  }
+
+  return false;
+}
+
+/* static */
+bool nsContentUtils::HasMutationListeners(Document* aDocument, uint32_t aType) {
+  nsPIDOMWindowInner* window =
+      aDocument ? aDocument->GetInnerWindow() : nullptr;
+
+  // This relies on EventListenerManager::AddEventListener, which sets
+  // all mutation bits when there is a listener for DOMSubtreeModified event.
+  return !window || window->HasMutationListeners(aType);
+}
+
+void nsContentUtils::MaybeFireNodeRemoved(nsINode* aChild, nsINode* aParent) {
+  MOZ_ASSERT(aChild, "Missing child");
+  MOZ_ASSERT(aChild->GetParentNode() == aParent, "Wrong parent");
+  MOZ_ASSERT(aChild->OwnerDoc() == aParent->OwnerDoc(), "Wrong owner-doc");
+
+  // Having an explicit check here since it's an easy mistake to fall into,
+  // and there might be existing code with problems. We'd rather be safe
+  // than fire DOMNodeRemoved in all corner cases. We also rely on it for
+  // nsAutoScriptBlockerSuppressNodeRemoved.
+  if (!IsSafeToRunScript()) {
+    // This checks that IsSafeToRunScript is true since we don't want to fire
+    // events when that is false. We can't rely on EventDispatcher to assert
+    // this in this situation since most of the time there are no mutation
+    // event listeners, in which case we won't even attempt to dispatch events.
+    // However this also allows for two exceptions. First off, we don't assert
+    // if the mutation happens to native anonymous content since we never fire
+    // mutation events on such content anyway.
+    // Second, we don't assert if sDOMNodeRemovedSuppressCount is true since
+    // that is a know case when we'd normally fire a mutation event, but can't
+    // make that safe and so we suppress it at this time. Ideally this should
+    // go away eventually.
+    if (!aChild->IsInNativeAnonymousSubtree() &&
+        !sDOMNodeRemovedSuppressCount) {
+      NS_ERROR("Want to fire DOMNodeRemoved event, but it's not safe");
+      WarnScriptWasIgnored(aChild->OwnerDoc());
+    }
+    return;
+  }
+
+  {
+    Document* doc = aParent->OwnerDoc();
+    if (MOZ_UNLIKELY(doc->DevToolsWatchingDOMMutations()) &&
+        aChild->IsInComposedDoc() && !aChild->ChromeOnlyAccess()) {
+      DispatchChromeEvent(doc, aChild, u"devtoolschildremoved"_ns,
+                          CanBubble::eNo, Cancelable::eNo);
+    }
+  }
+
+  if (HasMutationListeners(aChild, NS_EVENT_BITS_MUTATION_NODEREMOVED,
+                           aParent)) {
+    InternalMutationEvent mutation(true, eLegacyNodeRemoved);
+    mutation.mRelatedNode = aParent;
+
+    mozAutoSubtreeModified subtree(aParent->OwnerDoc(), aParent);
+    EventDispatcher::Dispatch(aChild, nullptr, &mutation);
+  }
+}
+
+void nsContentUtils::UnmarkGrayJSListenersInCCGenerationDocuments() {
+  if (!sEventListenerManagersHash) {
+    return;
+  }
+
+  for (auto i = sEventListenerManagersHash->Iter(); !i.Done(); i.Next()) {
+    auto entry = static_cast<EventListenerManagerMapEntry*>(i.Get());
+    nsINode* n = static_cast<nsINode*>(entry->mListenerManager->GetTarget());
+    if (n && n->IsInComposedDoc() &&
+        nsCCUncollectableMarker::InGeneration(
+            n->OwnerDoc()->GetMarkedCCGeneration())) {
+      entry->mListenerManager->MarkForCC();
+    }
+  }
+}
+
+/* static */
+void nsContentUtils::TraverseListenerManager(
+    nsINode* aNode, nsCycleCollectionTraversalCallback& cb) {
+  if (!sEventListenerManagersHash) {
+    // We're already shut down, just return.
+    return;
+  }
+
+  auto entry = static_cast<EventListenerManagerMapEntry*>(
+      sEventListenerManagersHash->Search(aNode));
+  if (entry) {
+    CycleCollectionNoteChild(cb, entry->mListenerManager.get(),
+                             "[via hash] mListenerManager");
+  }
+}
+
+EventListenerManager* nsContentUtils::GetListenerManagerForNode(
+    nsINode* aNode) {
+  if (!sEventListenerManagersHash) {
+    // We're already shut down, don't bother creating an event listener
+    // manager.
+
+    return nullptr;
+  }
+
+  auto entry = static_cast<EventListenerManagerMapEntry*>(
+      sEventListenerManagersHash->Add(aNode, fallible));
+
+  if (!entry) {
+    return nullptr;
+  }
+
+  if (!entry->mListenerManager) {
+    entry->mListenerManager = new EventListenerManager(aNode);
+
+    aNode->SetFlags(NODE_HAS_LISTENERMANAGER);
+  }
+
+  return entry->mListenerManager;
+}
+
+EventListenerManager* nsContentUtils::GetExistingListenerManagerForNode(
+    const nsINode* aNode) {
+  if (!aNode->HasFlag(NODE_HAS_LISTENERMANAGER)) {
+    return nullptr;
+  }
+
+  if (!sEventListenerManagersHash) {
+    // We're already shut down, don't bother creating an event listener
+    // manager.
+
+    return nullptr;
+  }
+
+  auto entry = static_cast<EventListenerManagerMapEntry*>(
+      sEventListenerManagersHash->Search(aNode));
+  if (entry) {
+    return entry->mListenerManager;
+  }
+
+  return nullptr;
+}
+
+void nsContentUtils::AddEntryToDOMArenaTable(nsINode* aNode,
+                                             DOMArena* aDOMArena) {
+  MOZ_ASSERT(StaticPrefs::dom_arena_allocator_enabled_AtStartup());
+  MOZ_ASSERT_IF(sDOMArenaHashtable, !sDOMArenaHashtable->Contains(aNode));
+  MOZ_ASSERT(!aNode->HasFlag(NODE_KEEPS_DOMARENA));
+  if (!sDOMArenaHashtable) {
+    sDOMArenaHashtable =
+        new nsRefPtrHashtable<nsPtrHashKey<const nsINode>, dom::DOMArena>();
+  }
+  aNode->SetFlags(NODE_KEEPS_DOMARENA);
+  sDOMArenaHashtable->InsertOrUpdate(aNode, RefPtr<DOMArena>(aDOMArena));
+}
+
+already_AddRefed<DOMArena> nsContentUtils::TakeEntryFromDOMArenaTable(
+    const nsINode* aNode) {
+  MOZ_ASSERT(sDOMArenaHashtable->Contains(aNode));
+  MOZ_ASSERT(StaticPrefs::dom_arena_allocator_enabled_AtStartup());
+  RefPtr<DOMArena> arena;
+  sDOMArenaHashtable->Remove(aNode, getter_AddRefs(arena));
+  return arena.forget();
+}
+
+/* static */
+void nsContentUtils::RemoveListenerManager(nsINode* aNode) {
+  if (sEventListenerManagersHash) {
+    auto entry = static_cast<EventListenerManagerMapEntry*>(
+        sEventListenerManagersHash->Search(aNode));
+    if (entry) {
+      RefPtr<EventListenerManager> listenerManager;
+      listenerManager.swap(entry->mListenerManager);
+      // Remove the entry and *then* do operations that could cause further
+      // modification of sEventListenerManagersHash.  See bug 334177.
+      sEventListenerManagersHash->RawRemove(entry);
+      if (listenerManager) {
+        listenerManager->Disconnect();
+      }
+    }
+  }
+}
+
+/* static */
+bool nsContentUtils::IsValidNodeName(nsAtom* aLocalName, nsAtom* aPrefix,
+                                     int32_t aNamespaceID) {
+  if (aNamespaceID == kNameSpaceID_Unknown) {
+    return false;
+  }
+
+  if (!aPrefix) {
+    // If the prefix is null, then either the QName must be xmlns or the
+    // namespace must not be XMLNS.
+    return (aLocalName == nsGkAtoms::xmlns) ==
+           (aNamespaceID == kNameSpaceID_XMLNS);
+  }
+
+  // If the prefix is non-null then the namespace must not be null.
+  if (aNamespaceID == kNameSpaceID_None) {
+    return false;
+  }
+
+  // If the namespace is the XMLNS namespace then the prefix must be xmlns,
+  // but the localname must not be xmlns.
+  if (aNamespaceID == kNameSpaceID_XMLNS) {
+    return aPrefix == nsGkAtoms::xmlns && aLocalName != nsGkAtoms::xmlns;
+  }
+
+  // If the namespace is not the XMLNS namespace then the prefix must not be
+  // xmlns.
+  // If the namespace is the XML namespace then the prefix can be anything.
+  // If the namespace is not the XML namespace then the prefix must not be xml.
+  return aPrefix != nsGkAtoms::xmlns &&
+         (aNamespaceID == kNameSpaceID_XML || aPrefix != nsGkAtoms::xml);
+}
+
+already_AddRefed<DocumentFragment> nsContentUtils::CreateContextualFragment(
+    nsINode* aContextNode, const nsAString& aFragment,
+    bool aPreventScriptExecution, ErrorResult& aRv) {
+  if (!aContextNode) {
+    aRv.Throw(NS_ERROR_INVALID_ARG);
+    return nullptr;
+  }
+
+  // If we don't have a document here, we can't get the right security context
+  // for compiling event handlers... so just bail out.
+  RefPtr<Document> document = aContextNode->OwnerDoc();
+  bool isHTML = document->IsHTMLDocument();
+
+  if (isHTML) {
+    RefPtr<DocumentFragment> frag = new (document->NodeInfoManager())
+        DocumentFragment(document->NodeInfoManager());
+
+    Element* element = aContextNode->GetAsElementOrParentElement();
+    if (element && !element->IsHTMLElement(nsGkAtoms::html)) {
+      aRv = ParseFragmentHTML(
+          aFragment, frag, element->NodeInfo()->NameAtom(),
+          element->GetNameSpaceID(),
+          (document->GetCompatibilityMode() == eCompatibility_NavQuirks),
+          aPreventScriptExecution);
+    } else {
+      aRv = ParseFragmentHTML(
+          aFragment, frag, nsGkAtoms::body, kNameSpaceID_XHTML,
+          (document->GetCompatibilityMode() == eCompatibility_NavQuirks),
+          aPreventScriptExecution);
+    }
+
+    return frag.forget();
+  }
+
+  AutoTArray<nsString, 32> tagStack;
+  nsAutoString uriStr, nameStr;
+  for (Element* element : aContextNode->InclusiveAncestorsOfType<Element>()) {
+    nsString& tagName = *tagStack.AppendElement();
+    // It mostly doesn't actually matter what tag name we use here: XML doesn't
+    // have parsing that depends on the open tag stack, apart from namespace
+    // declarations.  So this whole tagStack bit is just there to get the right
+    // namespace declarations to the XML parser.  That said, the parser _is_
+    // going to create elements with the tag names we provide here, so we need
+    // to make sure they are not names that can trigger custom element
+    // constructors.  Just make up a name that is never going to be a valid
+    // custom element name.
+    //
+    // The principled way to do this would probably be to add a new FromParser
+    // value and make sure we use it when creating the context elements, then
+    // make sure we teach all FromParser consumers (and in particular the custom
+    // element code) about it as needed.  But right now the XML parser never
+    // actually uses FromParser values other than NOT_FROM_PARSER, and changing
+    // that is pretty complicated.
+    tagName.AssignLiteral("notacustomelement");
+
+    // see if we need to add xmlns declarations
+    uint32_t count = element->GetAttrCount();
+    bool setDefaultNamespace = false;
+    if (count > 0) {
+      uint32_t index;
+
+      for (index = 0; index < count; index++) {
+        const BorrowedAttrInfo info = element->GetAttrInfoAt(index);
+        const nsAttrName* name = info.mName;
+        if (name->NamespaceEquals(kNameSpaceID_XMLNS)) {
+          info.mValue->ToString(uriStr);
+
+          // really want something like nsXMLContentSerializer::SerializeAttr
+          tagName.AppendLiteral(" xmlns");  // space important
+          if (name->GetPrefix()) {
+            tagName.Append(char16_t(':'));
+            name->LocalName()->ToString(nameStr);
+            tagName.Append(nameStr);
+          } else {
+            setDefaultNamespace = true;
+          }
+          tagName.AppendLiteral(R"(=")");
+          tagName.Append(uriStr);
+          tagName.Append('"');
+        }
+      }
+    }
+
+    if (!setDefaultNamespace) {
+      mozilla::dom::NodeInfo* info = element->NodeInfo();
+      if (!info->GetPrefixAtom() && info->NamespaceID() != kNameSpaceID_None) {
+        // We have no namespace prefix, but have a namespace ID.  Push
+        // default namespace attr in, so that our kids will be in our
+        // namespace.
+        info->GetNamespaceURI(uriStr);
+        tagName.AppendLiteral(R"( xmlns=")");
+        tagName.Append(uriStr);
+        tagName.Append('"');
+      }
+    }
+  }
+
+  RefPtr<DocumentFragment> frag;
+  aRv = ParseFragmentXML(aFragment, document, tagStack, aPreventScriptExecution,
+                         -1, getter_AddRefs(frag));
+  return frag.forget();
+}
+
+/* static */
+void nsContentUtils::DropFragmentParsers() {
+  NS_IF_RELEASE(sHTMLFragmentParser);
+  NS_IF_RELEASE(sXMLFragmentParser);
+  NS_IF_RELEASE(sXMLFragmentSink);
+}
+
+/* static */
+void nsContentUtils::XPCOMShutdown() { nsContentUtils::DropFragmentParsers(); }
+
+/* Helper function to compuate Sanitization Flags for ParseFramentHTML/XML */
+uint32_t computeSanitizationFlags(nsIPrincipal* aPrincipal, int32_t aFlags) {
+  uint32_t sanitizationFlags = 0;
+  if (aPrincipal->IsSystemPrincipal()) {
+    if (aFlags < 0) {
+      // if this is a chrome-privileged document and no explicit flags
+      // were passed, then use this sanitization flags.
+      sanitizationFlags = nsIParserUtils::SanitizerAllowStyle |
+                          nsIParserUtils::SanitizerAllowComments |
+                          nsIParserUtils::SanitizerDropForms |
+                          nsIParserUtils::SanitizerLogRemovals;
+    } else {
+      // if the caller explicitly passes flags, then we use those
+      // flags but additionally drop forms.
+      sanitizationFlags = aFlags | nsIParserUtils::SanitizerDropForms;
+    }
+  } else if (aFlags >= 0) {
+    // aFlags by default is -1 and is only ever non equal to -1 if the
+    // caller of ParseFragmentHTML/ParseFragmentXML is
+    // ParserUtils::ParseFragment(). Only in that case we should use
+    // the sanitization flags passed within aFlags.
+    sanitizationFlags = aFlags;
+  }
+  return sanitizationFlags;
+}
+
+/* static */
+bool AllowsUnsanitizedContentForAboutNewTab(nsIPrincipal* aPrincipal) {
+  if (StaticPrefs::dom_about_newtab_sanitization_enabled() ||
+      !aPrincipal->SchemeIs("about")) {
+    return false;
+  }
+  uint32_t aboutModuleFlags = 0;
+  aPrincipal->GetAboutModuleFlags(&aboutModuleFlags);
+  return aboutModuleFlags & nsIAboutModule::ALLOW_UNSANITIZED_CONTENT;
+}
+
+/* static */
+nsresult nsContentUtils::ParseFragmentHTML(
+    const nsAString& aSourceBuffer, nsIContent* aTargetNode,
+    nsAtom* aContextLocalName, int32_t aContextNamespace, bool aQuirks,
+    bool aPreventScriptExecution, int32_t aFlags) {
+  AutoTimelineMarker m(aTargetNode->OwnerDoc()->GetDocShell(), "Parse HTML");
+
+  if (nsContentUtils::sFragmentParsingActive) {
+    MOZ_ASSERT_UNREACHABLE("Re-entrant fragment parsing attempted.");
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
+  mozilla::AutoRestore<bool> guard(nsContentUtils::sFragmentParsingActive);
+  nsContentUtils::sFragmentParsingActive = true;
+  if (!sHTMLFragmentParser) {
+    NS_ADDREF(sHTMLFragmentParser = new nsHtml5StringParser());
+    // Now sHTMLFragmentParser owns the object
+  }
+
+  nsCOMPtr<nsIPrincipal> nodePrincipal = aTargetNode->NodePrincipal();
+
+#ifdef DEBUG
+  // aFlags should always be -1 unless the caller of ParseFragmentHTML
+  // is ParserUtils::ParseFragment() which is the only caller that intends
+  // sanitization. For all other callers we need to ensure to call
+  // AuditParsingOfHTMLXMLFragments.
+  if (aFlags < 0) {
+    DOMSecurityMonitor::AuditParsingOfHTMLXMLFragments(nodePrincipal,
+                                                       aSourceBuffer);
+  }
+#endif
+
+  nsIContent* target = aTargetNode;
+
+  RefPtr<Document> doc = aTargetNode->OwnerDoc();
+  RefPtr<DocumentFragment> fragment;
+  // We sanitize if the fragment occurs in a system privileged
+  // context, an about: page, or if there are explicit sanitization flags.
+  // Please note that about:blank and about:srcdoc inherit the security
+  // context from the embedding context and hence are not loaded using
+  // an about: scheme principal.
+  bool shouldSanitize = nodePrincipal->IsSystemPrincipal() ||
+                        nodePrincipal->SchemeIs("about") || aFlags >= 0;
+  if (shouldSanitize &&
+      !AllowsUnsanitizedContentForAboutNewTab(nodePrincipal)) {
+    if (!doc->IsLoadedAsData()) {
+      doc = nsContentUtils::CreateInertHTMLDocument(doc);
+      if (!doc) {
+        return NS_ERROR_FAILURE;
+      }
+    }
+    fragment =
+        new (doc->NodeInfoManager()) DocumentFragment(doc->NodeInfoManager());
+    target = fragment;
+  }
+
+  nsresult rv = sHTMLFragmentParser->ParseFragment(
+      aSourceBuffer, target, aContextLocalName, aContextNamespace, aQuirks,
+      aPreventScriptExecution);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (fragment) {
+    uint32_t sanitizationFlags =
+        computeSanitizationFlags(nodePrincipal, aFlags);
+    // Don't fire mutation events for nodes removed by the sanitizer.
+    nsAutoScriptBlockerSuppressNodeRemoved scriptBlocker;
+    nsTreeSanitizer sanitizer(sanitizationFlags);
+    sanitizer.Sanitize(fragment);
+
+    ErrorResult error;
+    aTargetNode->AppendChild(*fragment, error);
+    rv = error.StealNSResult();
+  }
+
+  return rv;
+}
+
+/* static */
+nsresult nsContentUtils::ParseDocumentHTML(
+    const nsAString& aSourceBuffer, Document* aTargetDocument,
+    bool aScriptingEnabledForNoscriptParsing) {
+  AutoTimelineMarker m(aTargetDocument->GetDocShell(), "Parse HTML");
+
+  if (nsContentUtils::sFragmentParsingActive) {
+    MOZ_ASSERT_UNREACHABLE("Re-entrant fragment parsing attempted.");
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
+  mozilla::AutoRestore<bool> guard(nsContentUtils::sFragmentParsingActive);
+  nsContentUtils::sFragmentParsingActive = true;
+  if (!sHTMLFragmentParser) {
+    NS_ADDREF(sHTMLFragmentParser = new nsHtml5StringParser());
+    // Now sHTMLFragmentParser owns the object
+  }
+  nsresult rv = sHTMLFragmentParser->ParseDocument(
+      aSourceBuffer, aTargetDocument, aScriptingEnabledForNoscriptParsing);
+  return rv;
+}
+
+/* static */
+nsresult nsContentUtils::ParseFragmentXML(const nsAString& aSourceBuffer,
+                                          Document* aDocument,
+                                          nsTArray<nsString>& aTagStack,
+                                          bool aPreventScriptExecution,
+                                          int32_t aFlags,
+                                          DocumentFragment** aReturn) {
+  AutoTimelineMarker m(aDocument->GetDocShell(), "Parse XML");
+
+  if (nsContentUtils::sFragmentParsingActive) {
+    MOZ_ASSERT_UNREACHABLE("Re-entrant fragment parsing attempted.");
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
+  mozilla::AutoRestore<bool> guard(nsContentUtils::sFragmentParsingActive);
+  nsContentUtils::sFragmentParsingActive = true;
+  if (!sXMLFragmentParser) {
+    RefPtr<nsParser> parser = new nsParser();
+    parser.forget(&sXMLFragmentParser);
+    // sXMLFragmentParser now owns the parser
+  }
+  if (!sXMLFragmentSink) {
+    NS_NewXMLFragmentContentSink(&sXMLFragmentSink);
+    // sXMLFragmentSink now owns the sink
+  }
+  nsCOMPtr<nsIContentSink> contentsink = do_QueryInterface(sXMLFragmentSink);
+  MOZ_ASSERT(contentsink, "Sink doesn't QI to nsIContentSink!");
+  sXMLFragmentParser->SetContentSink(contentsink);
+
+  RefPtr<Document> doc;
+  nsCOMPtr<nsIPrincipal> nodePrincipal = aDocument->NodePrincipal();
+
+#ifdef DEBUG
+  // aFlags should always be -1 unless the caller of ParseFragmentXML
+  // is ParserUtils::ParseFragment() which is the only caller that intends
+  // sanitization. For all other callers we need to ensure to call
+  // AuditParsingOfHTMLXMLFragments.
+  if (aFlags < 0) {
+    DOMSecurityMonitor::AuditParsingOfHTMLXMLFragments(nodePrincipal,
+                                                       aSourceBuffer);
+  }
+#endif
+
+  // We sanitize if the fragment occurs in a system privileged
+  // context, an about: page, or if there are explicit sanitization flags.
+  // Please note that about:blank and about:srcdoc inherit the security
+  // context from the embedding context and hence are not loaded using
+  // an about: scheme principal.
+  bool shouldSanitize = nodePrincipal->IsSystemPrincipal() ||
+                        nodePrincipal->SchemeIs("about") || aFlags >= 0;
+  if (shouldSanitize && !aDocument->IsLoadedAsData()) {
+    doc = nsContentUtils::CreateInertXMLDocument(aDocument);
+  } else {
+    doc = aDocument;
+  }
+
+  sXMLFragmentSink->SetTargetDocument(doc);
+  sXMLFragmentSink->SetPreventScriptExecution(aPreventScriptExecution);
+
+  nsresult rv = sXMLFragmentParser->ParseFragment(aSourceBuffer, aTagStack);
+  if (NS_FAILED(rv)) {
+    // Drop the fragment parser and sink that might be in an inconsistent state
+    NS_IF_RELEASE(sXMLFragmentParser);
+    NS_IF_RELEASE(sXMLFragmentSink);
+    return rv;
+  }
+
+  rv = sXMLFragmentSink->FinishFragmentParsing(aReturn);
+
+  sXMLFragmentParser->Reset();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (shouldSanitize) {
+    uint32_t sanitizationFlags =
+        computeSanitizationFlags(nodePrincipal, aFlags);
+    // Don't fire mutation events for nodes removed by the sanitizer.
+    nsAutoScriptBlockerSuppressNodeRemoved scriptBlocker;
+    nsTreeSanitizer sanitizer(sanitizationFlags);
+    sanitizer.Sanitize(*aReturn);
+  }
+
+  return rv;
+}
+
+/* static */
+nsresult nsContentUtils::ConvertToPlainText(const nsAString& aSourceBuffer,
+                                            nsAString& aResultBuffer,
+                                            uint32_t aFlags,
+                                            uint32_t aWrapCol) {
+  RefPtr<Document> document = nsContentUtils::CreateInertHTMLDocument(nullptr);
+  if (!document) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsresult rv = nsContentUtils::ParseDocumentHTML(
+      aSourceBuffer, document,
+      !(aFlags & nsIDocumentEncoder::OutputNoScriptContent));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIDocumentEncoder> encoder = do_createDocumentEncoder("text/plain");
+
+  rv = encoder->Init(document, u"text/plain"_ns, aFlags);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  encoder->SetWrapColumn(aWrapCol);
+
+  return encoder->EncodeToString(aResultBuffer);
+}
+
+static already_AddRefed<Document> CreateInertDocument(const Document* aTemplate,
+                                                      DocumentFlavor aFlavor) {
+  if (aTemplate) {
+    bool hasHad = true;
+    nsIScriptGlobalObject* sgo = aTemplate->GetScriptHandlingObject(hasHad);
+    NS_ENSURE_TRUE(sgo || !hasHad, nullptr);
+
+    nsCOMPtr<Document> doc;
+    nsresult rv = NS_NewDOMDocument(
+        getter_AddRefs(doc), u""_ns, u""_ns, nullptr,
+        aTemplate->GetDocumentURI(), aTemplate->GetDocBaseURI(),
+        aTemplate->NodePrincipal(), true, sgo, aFlavor);
+    if (NS_FAILED(rv)) {
+      return nullptr;
+    }
+    return doc.forget();
+  }
+  nsCOMPtr<nsIURI> uri;
+  NS_NewURI(getter_AddRefs(uri), "about:blank"_ns);
+  if (!uri) {
+    return nullptr;
+  }
+
+  RefPtr<NullPrincipal> nullPrincipal =
+      NullPrincipal::CreateWithoutOriginAttributes();
+  if (!nullPrincipal) {
+    return nullptr;
+  }
+
+  nsCOMPtr<Document> doc;
+  nsresult rv =
+      NS_NewDOMDocument(getter_AddRefs(doc), u""_ns, u""_ns, nullptr, uri, uri,
+                        nullPrincipal, true, nullptr, aFlavor);
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+  return doc.forget();
+}
+
+/* static */
+already_AddRefed<Document> nsContentUtils::CreateInertXMLDocument(
+    const Document* aTemplate) {
+  return CreateInertDocument(aTemplate, DocumentFlavorXML);
+}
+
+/* static */
+already_AddRefed<Document> nsContentUtils::CreateInertHTMLDocument(
+    const Document* aTemplate) {
+  return CreateInertDocument(aTemplate, DocumentFlavorHTML);
+}
+
+/* static */
+nsresult nsContentUtils::SetNodeTextContent(nsIContent* aContent,
+                                            const nsAString& aValue,
+                                            bool aTryReuse) {
+  // Fire DOMNodeRemoved mutation events before we do anything else.
+  nsCOMPtr<nsIContent> owningContent;
+
+  // Batch possible DOMSubtreeModified events.
+  mozAutoSubtreeModified subtree(nullptr, nullptr);
+
+  // Scope firing mutation events so that we don't carry any state that
+  // might be stale
+  {
+    // We're relying on mozAutoSubtreeModified to keep a strong reference if
+    // needed.
+    Document* doc = aContent->OwnerDoc();
+
+    // Optimize the common case of there being no observers
+    if (HasMutationListeners(doc, NS_EVENT_BITS_MUTATION_NODEREMOVED)) {
+      subtree.UpdateTarget(doc, nullptr);
+      owningContent = aContent;
+      nsCOMPtr<nsINode> child;
+      bool skipFirst = aTryReuse;
+      for (child = aContent->GetFirstChild();
+           child && child->GetParentNode() == aContent;
+           child = child->GetNextSibling()) {
+        if (skipFirst && child->IsText()) {
+          skipFirst = false;
+          continue;
+        }
+        nsContentUtils::MaybeFireNodeRemoved(child, aContent);
+      }
+    }
+  }
+
+  // Might as well stick a batch around this since we're performing several
+  // mutations.
+  mozAutoDocUpdate updateBatch(aContent->GetComposedDoc(), true);
+  nsAutoMutationBatch mb;
+
+  if (aTryReuse && !aValue.IsEmpty()) {
+    // Let's remove nodes until we find a eTEXT.
+    while (aContent->HasChildren()) {
+      nsIContent* child = aContent->GetFirstChild();
+      if (child->IsText()) {
+        break;
+      }
+      aContent->RemoveChildNode(child, true);
+    }
+
+    // If we have a node, it must be a eTEXT and we reuse it.
+    if (aContent->HasChildren()) {
+      nsIContent* child = aContent->GetFirstChild();
+      nsresult rv = child->AsText()->SetText(aValue, true);
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      // All the following nodes, if they exist, must be deleted.
+      while (nsIContent* nextChild = child->GetNextSibling()) {
+        aContent->RemoveChildNode(nextChild, true);
+      }
+    }
+
+    if (aContent->HasChildren()) {
+      return NS_OK;
+    }
+  } else {
+    mb.Init(aContent, true, false);
+    while (aContent->HasChildren()) {
+      aContent->RemoveChildNode(aContent->GetFirstChild(), true);
+    }
+  }
+  mb.RemovalDone();
+
+  if (aValue.IsEmpty()) {
+    return NS_OK;
+  }
+
+  RefPtr<nsTextNode> textContent = new (aContent->NodeInfo()->NodeInfoManager())
+      nsTextNode(aContent->NodeInfo()->NodeInfoManager());
+
+  textContent->SetText(aValue, true);
+
+  ErrorResult rv;
+  aContent->AppendChildTo(textContent, true, rv);
+  mb.NodesAdded();
+  return rv.StealNSResult();
+}
+
+static bool AppendNodeTextContentsRecurse(const nsINode* aNode,
+                                          nsAString& aResult,
+                                          const fallible_t& aFallible) {
+  for (nsIContent* child = aNode->GetFirstChild(); child;
+       child = child->GetNextSibling()) {
+    if (child->IsElement()) {
+      bool ok = AppendNodeTextContentsRecurse(child, aResult, aFallible);
+      if (!ok) {
+        return false;
+      }
+    } else if (Text* text = child->GetAsText()) {
+      bool ok = text->AppendTextTo(aResult, aFallible);
+      if (!ok) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+/* static */
+bool nsContentUtils::AppendNodeTextContent(const nsINode* aNode, bool aDeep,
+                                           nsAString& aResult,
+                                           const fallible_t& aFallible) {
+  if (const Text* text = aNode->GetAsText()) {
+    return text->AppendTextTo(aResult, aFallible);
+  }
+  if (aDeep) {
+    return AppendNodeTextContentsRecurse(aNode, aResult, aFallible);
+  }
+
+  for (nsIContent* child = aNode->GetFirstChild(); child;
+       child = child->GetNextSibling()) {
+    if (Text* text = child->GetAsText()) {
+      bool ok = text->AppendTextTo(aResult, fallible);
+      if (!ok) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+bool nsContentUtils::HasNonEmptyTextContent(
+    nsINode* aNode, TextContentDiscoverMode aDiscoverMode) {
+  for (nsIContent* child = aNode->GetFirstChild(); child;
+       child = child->GetNextSibling()) {
+    if (child->IsText() && child->TextLength() > 0) {
+      return true;
+    }
+
+    if (aDiscoverMode == eRecurseIntoChildren &&
+        HasNonEmptyTextContent(child, aDiscoverMode)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+/* static */
+bool nsContentUtils::IsInSameAnonymousTree(const nsINode* aNode,
+                                           const nsINode* aOtherNode) {
+  MOZ_ASSERT(aNode, "Must have a node to work with");
+  MOZ_ASSERT(aOtherNode, "Must have a content to work with");
+
+  const bool anon = aNode->IsInNativeAnonymousSubtree();
+  if (anon != aOtherNode->IsInNativeAnonymousSubtree()) {
+    return false;
+  }
+
+  if (anon) {
+    return aOtherNode->GetClosestNativeAnonymousSubtreeRoot() ==
+           aNode->GetClosestNativeAnonymousSubtreeRoot();
+  }
+
+  // FIXME: This doesn't deal with disconnected nodes whatsoever, but it didn't
+  // use to either. Maybe that's fine.
+  return aNode->GetContainingShadow() == aOtherNode->GetContainingShadow();
+}
+
+/* static */
+bool nsContentUtils::IsInInteractiveHTMLContent(const Element* aElement,
+                                                const Element* aStop) {
+  const Element* element = aElement;
+  while (element && element != aStop) {
+    if (element->IsInteractiveHTMLContent()) {
+      return true;
+    }
+    element = element->GetFlattenedTreeParentElement();
+  }
+  return false;
+}
+
+/* static */
+void nsContentUtils::NotifyInstalledMenuKeyboardListener(bool aInstalling) {
+  IMEStateManager::OnInstalledMenuKeyboardListener(aInstalling);
+}
+
+/* static */
+bool nsContentUtils::SchemeIs(nsIURI* aURI, const char* aScheme) {
+  nsCOMPtr<nsIURI> baseURI = NS_GetInnermostURI(aURI);
+  NS_ENSURE_TRUE(baseURI, false);
+  return baseURI->SchemeIs(aScheme);
+}
+
+bool nsContentUtils::IsExpandedPrincipal(nsIPrincipal* aPrincipal) {
+  return aPrincipal && aPrincipal->GetIsExpandedPrincipal();
+}
+
+bool nsContentUtils::IsSystemOrExpandedPrincipal(nsIPrincipal* aPrincipal) {
+  return (aPrincipal && aPrincipal->IsSystemPrincipal()) ||
+         IsExpandedPrincipal(aPrincipal);
+}
+
+nsIPrincipal* nsContentUtils::GetSystemPrincipal() {
+  MOZ_ASSERT(IsInitialized());
+  return sSystemPrincipal;
+}
+
+bool nsContentUtils::CombineResourcePrincipals(
+    nsCOMPtr<nsIPrincipal>* aResourcePrincipal, nsIPrincipal* aExtraPrincipal) {
+  if (!aExtraPrincipal) {
+    return false;
+  }
+  if (!*aResourcePrincipal) {
+    *aResourcePrincipal = aExtraPrincipal;
+    return true;
+  }
+  if (*aResourcePrincipal == aExtraPrincipal) {
+    return false;
+  }
+  bool subsumes;
+  if (NS_SUCCEEDED(
+          (*aResourcePrincipal)->Subsumes(aExtraPrincipal, &subsumes)) &&
+      subsumes) {
+    return false;
+  }
+  *aResourcePrincipal = sSystemPrincipal;
+  return true;
+}
+
+/* static */
+void nsContentUtils::TriggerLink(nsIContent* aContent, nsIURI* aLinkURI,
+                                 const nsString& aTargetSpec, bool aClick,
+                                 bool aIsTrusted) {
+  MOZ_ASSERT(aLinkURI, "No link URI");
+
+  if (aContent->IsEditable() || !aContent->OwnerDoc()->LinkHandlingEnabled()) {
+    return;
+  }
+
+  nsCOMPtr<nsIDocShell> docShell = aContent->OwnerDoc()->GetDocShell();
+  if (!docShell) {
+    return;
+  }
+
+  if (!aClick) {
+    nsDocShell::Cast(docShell)->OnOverLink(aContent, aLinkURI, aTargetSpec);
+    return;
+  }
+
+  // Check that this page is allowed to load this URI.
+  nsresult proceed = NS_OK;
+
+  if (sSecurityManager) {
+    uint32_t flag = static_cast<uint32_t>(nsIScriptSecurityManager::STANDARD);
+    proceed = sSecurityManager->CheckLoadURIWithPrincipal(
+        aContent->NodePrincipal(), aLinkURI, flag,
+        aContent->OwnerDoc()->InnerWindowID());
+  }
+
+  // Only pass off the click event if the script security manager says it's ok.
+  // We need to rest aTargetSpec for forced downloads.
+  if (NS_SUCCEEDED(proceed)) {
+    // A link/area element with a download attribute is allowed to set
+    // a pseudo Content-Disposition header.
+    // For security reasons we only allow websites to declare same-origin
+    // resources as downloadable. If this check fails we will just do the normal
+    // thing (i.e. navigate to the resource).
+    nsAutoString fileName;
+    if ((!aContent->IsHTMLElement(nsGkAtoms::a) &&
+         !aContent->IsHTMLElement(nsGkAtoms::area) &&
+         !aContent->IsSVGElement(nsGkAtoms::a)) ||
+        !aContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::download,
+                                        fileName) ||
+        NS_FAILED(aContent->NodePrincipal()->CheckMayLoad(aLinkURI, true))) {
+      fileName.SetIsVoid(true);  // No actionable download attribute was found.
+    }
+
+    nsCOMPtr<nsIPrincipal> triggeringPrincipal = aContent->NodePrincipal();
+    nsCOMPtr<nsIContentSecurityPolicy> csp = aContent->GetCsp();
+
+    // Sanitize fileNames containing null characters by replacing them with
+    // underscores.
+    if (!fileName.IsVoid()) {
+      fileName.ReplaceChar(char16_t(0), '_');
+    }
+    nsDocShell::Cast(docShell)->OnLinkClick(
+        aContent, aLinkURI, fileName.IsVoid() ? aTargetSpec : u""_ns, fileName,
+        nullptr, nullptr, UserActivation::IsHandlingUserInput(), aIsTrusted,
+        triggeringPrincipal, csp);
+  }
+}
+
+/* static */
+void nsContentUtils::GetLinkLocation(Element* aElement,
+                                     nsString& aLocationString) {
+  nsCOMPtr<nsIURI> hrefURI = aElement->GetHrefURI();
+  if (hrefURI) {
+    nsAutoCString specUTF8;
+    nsresult rv = hrefURI->GetSpec(specUTF8);
+    if (NS_SUCCEEDED(rv)) CopyUTF8toUTF16(specUTF8, aLocationString);
+  }
+}
+
+/* static */
+nsIWidget* nsContentUtils::GetTopLevelWidget(nsIWidget* aWidget) {
+  if (!aWidget) return nullptr;
+
+  return aWidget->GetTopLevelWidget();
+}
+
+/* static */
+const nsDependentString nsContentUtils::GetLocalizedEllipsis() {
+  static char16_t sBuf[4] = {0, 0, 0, 0};
+  if (!sBuf[0]) {
+    if (!SpoofLocaleEnglish()) {
+      nsAutoString tmp;
+      Preferences::GetLocalizedString("intl.ellipsis", tmp);
+      uint32_t len =
+          std::min(uint32_t(tmp.Length()), uint32_t(ArrayLength(sBuf) - 1));
+      CopyUnicodeTo(tmp, 0, sBuf, len);
+    }
+    if (!sBuf[0]) sBuf[0] = char16_t(0x2026);
+  }
+  return nsDependentString(sBuf);
+}
+
+/* static */
+void nsContentUtils::AddScriptBlocker() {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!sScriptBlockerCount) {
+    MOZ_ASSERT(sRunnersCountAtFirstBlocker == 0,
+               "Should not already have a count");
+    sRunnersCountAtFirstBlocker =
+        sBlockedScriptRunners ? sBlockedScriptRunners->Length() : 0;
+  }
+  ++sScriptBlockerCount;
+}
+
+#ifdef DEBUG
+static bool sRemovingScriptBlockers = false;
+#endif
+
+/* static */
+void nsContentUtils::RemoveScriptBlocker() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!sRemovingScriptBlockers);
+  NS_ASSERTION(sScriptBlockerCount != 0, "Negative script blockers");
+  --sScriptBlockerCount;
+  if (sScriptBlockerCount) {
+    return;
+  }
+
+  if (!sBlockedScriptRunners) {
+    return;
+  }
+
+  uint32_t firstBlocker = sRunnersCountAtFirstBlocker;
+  uint32_t lastBlocker = sBlockedScriptRunners->Length();
+  uint32_t originalFirstBlocker = firstBlocker;
+  uint32_t blockersCount = lastBlocker - firstBlocker;
+  sRunnersCountAtFirstBlocker = 0;
+  NS_ASSERTION(firstBlocker <= lastBlocker, "bad sRunnersCountAtFirstBlocker");
+
+  while (firstBlocker < lastBlocker) {
+    nsCOMPtr<nsIRunnable> runnable;
+    runnable.swap((*sBlockedScriptRunners)[firstBlocker]);
+    ++firstBlocker;
+
+    // Calling the runnable can reenter us
+    {
+      AUTO_PROFILE_FOLLOWING_RUNNABLE(runnable);
+      runnable->Run();
+    }
+    // So can dropping the reference to the runnable
+    runnable = nullptr;
+
+    NS_ASSERTION(sRunnersCountAtFirstBlocker == 0, "Bad count");
+    NS_ASSERTION(!sScriptBlockerCount, "This is really bad");
+  }
+#ifdef DEBUG
+  AutoRestore<bool> removingScriptBlockers(sRemovingScriptBlockers);
+  sRemovingScriptBlockers = true;
+#endif
+  sBlockedScriptRunners->RemoveElementsAt(originalFirstBlocker, blockersCount);
+}
+
+/* static */
+already_AddRefed<nsPIDOMWindowOuter>
+nsContentUtils::GetMostRecentNonPBWindow() {
+  nsCOMPtr<nsIWindowMediator> wm = do_GetService(NS_WINDOWMEDIATOR_CONTRACTID);
+
+  nsCOMPtr<mozIDOMWindowProxy> window;
+  wm->GetMostRecentNonPBWindow(u"navigator:browser", getter_AddRefs(window));
+  nsCOMPtr<nsPIDOMWindowOuter> pwindow;
+  pwindow = do_QueryInterface(window);
+
+  return pwindow.forget();
+}
+
+/* static */
+void nsContentUtils::WarnScriptWasIgnored(Document* aDocument) {
+  nsAutoString msg;
+  bool privateBrowsing = false;
+  bool chromeContext = false;
+
+  if (aDocument) {
+    nsCOMPtr<nsIURI> uri = aDocument->GetDocumentURI();
+    if (uri) {
+      msg.Append(NS_ConvertUTF8toUTF16(uri->GetSpecOrDefault()));
+      msg.AppendLiteral(" : ");
+    }
+    privateBrowsing =
+        !!aDocument->NodePrincipal()->OriginAttributesRef().mPrivateBrowsingId;
+    chromeContext = aDocument->NodePrincipal()->IsSystemPrincipal();
+  }
+
+  msg.AppendLiteral(
+      "Unable to run script because scripts are blocked internally.");
+  LogSimpleConsoleError(msg, "DOM"_ns, privateBrowsing, chromeContext);
+}
+
+/* static */
+void nsContentUtils::AddScriptRunner(already_AddRefed<nsIRunnable> aRunnable) {
+  nsCOMPtr<nsIRunnable> runnable = aRunnable;
+  if (!runnable) {
+    return;
+  }
+
+  if (sScriptBlockerCount) {
+    sBlockedScriptRunners->AppendElement(runnable.forget());
+    return;
+  }
+
+  AUTO_PROFILE_FOLLOWING_RUNNABLE(runnable);
+  runnable->Run();
+}
+
+/* static */
+void nsContentUtils::AddScriptRunner(nsIRunnable* aRunnable) {
+  nsCOMPtr<nsIRunnable> runnable = aRunnable;
+  AddScriptRunner(runnable.forget());
+}
+
+/* static */ bool nsContentUtils::IsSafeToRunScript() {
+  MOZ_ASSERT(NS_IsMainThread(),
+             "This static variable only makes sense on the main thread!");
+  return sScriptBlockerCount == 0;
+}
+
+/* static */
+void nsContentUtils::RunInStableState(already_AddRefed<nsIRunnable> aRunnable) {
+  MOZ_ASSERT(CycleCollectedJSContext::Get(), "Must be on a script thread!");
+  CycleCollectedJSContext::Get()->RunInStableState(std::move(aRunnable));
+}
+
+/* static */
+void nsContentUtils::AddPendingIDBTransaction(
+    already_AddRefed<nsIRunnable> aTransaction) {
+  MOZ_ASSERT(CycleCollectedJSContext::Get(), "Must be on a script thread!");
+  CycleCollectedJSContext::Get()->AddPendingIDBTransaction(
+      std::move(aTransaction));
+}
+
+/* static */
+bool nsContentUtils::IsInStableOrMetaStableState() {
+  MOZ_ASSERT(CycleCollectedJSContext::Get(), "Must be on a script thread!");
+  return CycleCollectedJSContext::Get()->IsInStableOrMetaStableState();
+}
+
+/* static */
+void nsContentUtils::HidePopupsInDocument(Document* aDocument) {
+  RefPtr<nsXULPopupManager> pm = nsXULPopupManager::GetInstance();
+  if (!pm || !aDocument) {
+    return;
+  }
+  nsCOMPtr<nsIDocShellTreeItem> docShellToHide = aDocument->GetDocShell();
+  if (docShellToHide) {
+    pm->HidePopupsInDocShell(docShellToHide);
+  }
+}
+
+/* static */
+already_AddRefed<nsIDragSession> nsContentUtils::GetDragSession() {
+  nsCOMPtr<nsIDragSession> dragSession;
+  nsCOMPtr<nsIDragService> dragService =
+      do_GetService("@mozilla.org/widget/dragservice;1");
+  if (dragService) dragService->GetCurrentSession(getter_AddRefs(dragSession));
+  return dragSession.forget();
+}
+
+/* static */
+nsresult nsContentUtils::SetDataTransferInEvent(WidgetDragEvent* aDragEvent) {
+  if (aDragEvent->mDataTransfer || !aDragEvent->IsTrusted()) {
+    return NS_OK;
+  }
+
+  // For dragstart events, the data transfer object is
+  // created before the event fires, so it should already be set. For other
+  // drag events, get the object from the drag session.
+  NS_ASSERTION(aDragEvent->mMessage != eDragStart,
+               "draggesture event created without a dataTransfer");
+
+  nsCOMPtr<nsIDragSession> dragSession = GetDragSession();
+  NS_ENSURE_TRUE(dragSession, NS_OK);  // no drag in progress
+
+  RefPtr<DataTransfer> initialDataTransfer = dragSession->GetDataTransfer();
+  if (!initialDataTransfer) {
+    // A dataTransfer won't exist when a drag was started by some other
+    // means, for instance calling the drag service directly, or a drag
+    // from another application. In either case, a new dataTransfer should
+    // be created that reflects the data.
+    initialDataTransfer =
+        new DataTransfer(aDragEvent->mTarget, aDragEvent->mMessage, true, -1);
+
+    // now set it in the drag session so we don't need to create it again
+    dragSession->SetDataTransfer(initialDataTransfer);
+  }
+
+  bool isCrossDomainSubFrameDrop = false;
+  if (aDragEvent->mMessage == eDrop) {
+    isCrossDomainSubFrameDrop = CheckForSubFrameDrop(dragSession, aDragEvent);
+  }
+
+  // each event should use a clone of the original dataTransfer.
+  initialDataTransfer->Clone(
+      aDragEvent->mTarget, aDragEvent->mMessage, aDragEvent->mUserCancelled,
+      isCrossDomainSubFrameDrop, getter_AddRefs(aDragEvent->mDataTransfer));
+  if (NS_WARN_IF(!aDragEvent->mDataTransfer)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  // for the dragenter and dragover events, initialize the drop effect
+  // from the drop action, which platform specific widget code sets before
+  // the event is fired based on the keyboard state.
+  if (aDragEvent->mMessage == eDragEnter || aDragEvent->mMessage == eDragOver) {
+    uint32_t action;
+    dragSession->GetDragAction(&action);
+    uint32_t effectAllowed = aDragEvent->mDataTransfer->EffectAllowedInt();
+    aDragEvent->mDataTransfer->SetDropEffectInt(
+        FilterDropEffect(action, effectAllowed));
+  } else if (aDragEvent->mMessage == eDrop ||
+             aDragEvent->mMessage == eDragEnd) {
+    // For the drop and dragend events, set the drop effect based on the
+    // last value that the dropEffect had. This will have been set in
+    // EventStateManager::PostHandleEvent for the last dragenter or
+    // dragover event.
+    aDragEvent->mDataTransfer->SetDropEffectInt(
+        initialDataTransfer->DropEffectInt());
+  }
+
+  return NS_OK;
+}
+
+/* static */
+uint32_t nsContentUtils::FilterDropEffect(uint32_t aAction,
+                                          uint32_t aEffectAllowed) {
+  // It is possible for the drag action to include more than one action, but
+  // the widget code which sets the action from the keyboard state should only
+  // be including one. If multiple actions were set, we just consider them in
+  //  the following order:
+  //   copy, link, move
+  if (aAction & nsIDragService::DRAGDROP_ACTION_COPY)
+    aAction = nsIDragService::DRAGDROP_ACTION_COPY;
+  else if (aAction & nsIDragService::DRAGDROP_ACTION_LINK)
+    aAction = nsIDragService::DRAGDROP_ACTION_LINK;
+  else if (aAction & nsIDragService::DRAGDROP_ACTION_MOVE)
+    aAction = nsIDragService::DRAGDROP_ACTION_MOVE;
+
+  // Filter the action based on the effectAllowed. If the effectAllowed
+  // doesn't include the action, then that action cannot be done, so adjust
+  // the action to something that is allowed. For a copy, adjust to move or
+  // link. For a move, adjust to copy or link. For a link, adjust to move or
+  // link. Otherwise, use none.
+  if (aAction & aEffectAllowed ||
+      aEffectAllowed == nsIDragService::DRAGDROP_ACTION_UNINITIALIZED)
+    return aAction;
+  if (aEffectAllowed & nsIDragService::DRAGDROP_ACTION_MOVE)
+    return nsIDragService::DRAGDROP_ACTION_MOVE;
+  if (aEffectAllowed & nsIDragService::DRAGDROP_ACTION_COPY)
+    return nsIDragService::DRAGDROP_ACTION_COPY;
+  if (aEffectAllowed & nsIDragService::DRAGDROP_ACTION_LINK)
+    return nsIDragService::DRAGDROP_ACTION_LINK;
+  return nsIDragService::DRAGDROP_ACTION_NONE;
+}
+
+/* static */
+bool nsContentUtils::CheckForSubFrameDrop(nsIDragSession* aDragSession,
+                                          WidgetDragEvent* aDropEvent) {
+  nsCOMPtr<nsIContent> target =
+      nsIContent::FromEventTargetOrNull(aDropEvent->mOriginalTarget);
+  if (!target) {
+    return true;
+  }
+
+  // Always allow dropping onto chrome shells.
+  BrowsingContext* targetBC = target->OwnerDoc()->GetBrowsingContext();
+  if (targetBC->IsChrome()) {
+    return false;
+  }
+
+  WindowContext* targetWC = target->OwnerDoc()->GetWindowContext();
+
+  // If there is no source browsing context, then this is a drag from another
+  // application, which should be allowed.
+  RefPtr<WindowContext> sourceWC;
+  aDragSession->GetSourceWindowContext(getter_AddRefs(sourceWC));
+  if (sourceWC) {
+    // Get each successive parent of the source document and compare it to
+    // the drop document. If they match, then this is a drag from a child frame.
+    for (sourceWC = sourceWC->GetParentWindowContext(); sourceWC;
+         sourceWC = sourceWC->GetParentWindowContext()) {
+      // If the source and the target match, then the drag started in a
+      // descendant frame. If the source is discarded, err on the side of
+      // caution and treat it as a subframe drag.
+      if (sourceWC == targetWC || sourceWC->IsDiscarded()) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+/* static */
+bool nsContentUtils::URIIsLocalFile(nsIURI* aURI) {
+  bool isFile;
+  nsCOMPtr<nsINetUtil> util = mozilla::components::IO::Service();
+
+  // Important: we do NOT test the entire URI chain here!
+  return util &&
+         NS_SUCCEEDED(util->ProtocolHasFlags(
+             aURI, nsIProtocolHandler::URI_IS_LOCAL_FILE, &isFile)) &&
+         isFile;
+}
+
+/* static */
+JSContext* nsContentUtils::GetCurrentJSContext() {
+  MOZ_ASSERT(IsInitialized());
+  if (!IsJSAPIActive()) {
+    return nullptr;
+  }
+  return danger::GetJSContext();
+}
+
+template <typename StringType, typename CharType>
+void _ASCIIToLowerInSitu(StringType& aStr) {
+  CharType* iter = aStr.BeginWriting();
+  CharType* end = aStr.EndWriting();
+  MOZ_ASSERT(iter && end);
+
+  while (iter != end) {
+    CharType c = *iter;
+    if (c >= 'A' && c <= 'Z') {
+      *iter = c + ('a' - 'A');
+    }
+    ++iter;
+  }
+}
+
+/* static */
+void nsContentUtils::ASCIIToLower(nsAString& aStr) {
+  return _ASCIIToLowerInSitu<nsAString, char16_t>(aStr);
+}
+
+/* static */
+void nsContentUtils::ASCIIToLower(nsACString& aStr) {
+  return _ASCIIToLowerInSitu<nsACString, char>(aStr);
+}
+
+template <typename StringType, typename CharType>
+void _ASCIIToLowerCopy(const StringType& aSource, StringType& aDest) {
+  uint32_t len = aSource.Length();
+  aDest.SetLength(len);
+  MOZ_ASSERT(aDest.Length() == len);
+
+  CharType* dest = aDest.BeginWriting();
+  MOZ_ASSERT(dest);
+
+  const CharType* iter = aSource.BeginReading();
+  const CharType* end = aSource.EndReading();
+  while (iter != end) {
+    CharType c = *iter;
+    *dest = (c >= 'A' && c <= 'Z') ? c + ('a' - 'A') : c;
+    ++iter;
+    ++dest;
+  }
+}
+
+/* static */
+void nsContentUtils::ASCIIToLower(const nsAString& aSource, nsAString& aDest) {
+  return _ASCIIToLowerCopy<nsAString, char16_t>(aSource, aDest);
+}
+
+/* static */
+void nsContentUtils::ASCIIToLower(const nsACString& aSource,
+                                  nsACString& aDest) {
+  return _ASCIIToLowerCopy<nsACString, char>(aSource, aDest);
+}
+
+template <typename StringType, typename CharType>
+void _ASCIIToUpperInSitu(StringType& aStr) {
+  CharType* iter = aStr.BeginWriting();
+  CharType* end = aStr.EndWriting();
+  MOZ_ASSERT(iter && end);
+
+  while (iter != end) {
+    CharType c = *iter;
+    if (c >= 'a' && c <= 'z') {
+      *iter = c + ('A' - 'a');
+    }
+    ++iter;
+  }
+}
+
+/* static */
+void nsContentUtils::ASCIIToUpper(nsAString& aStr) {
+  return _ASCIIToUpperInSitu<nsAString, char16_t>(aStr);
+}
+
+/* static */
+void nsContentUtils::ASCIIToUpper(nsACString& aStr) {
+  return _ASCIIToUpperInSitu<nsACString, char>(aStr);
+}
+
+template <typename StringType, typename CharType>
+void _ASCIIToUpperCopy(const StringType& aSource, StringType& aDest) {
+  uint32_t len = aSource.Length();
+  aDest.SetLength(len);
+  MOZ_ASSERT(aDest.Length() == len);
+
+  CharType* dest = aDest.BeginWriting();
+  MOZ_ASSERT(dest);
+
+  const CharType* iter = aSource.BeginReading();
+  const CharType* end = aSource.EndReading();
+  while (iter != end) {
+    CharType c = *iter;
+    *dest = (c >= 'a' && c <= 'z') ? c + ('A' - 'a') : c;
+    ++iter;
+    ++dest;
+  }
+}
+
+/* static */
+void nsContentUtils::ASCIIToUpper(const nsAString& aSource, nsAString& aDest) {
+  return _ASCIIToUpperCopy<nsAString, char16_t>(aSource, aDest);
+}
+
+/* static */
+void nsContentUtils::ASCIIToUpper(const nsACString& aSource,
+                                  nsACString& aDest) {
+  return _ASCIIToUpperCopy<nsACString, char>(aSource, aDest);
+}
+
+/* static */
+bool nsContentUtils::EqualsIgnoreASCIICase(nsAtom* aAtom1, nsAtom* aAtom2) {
+  if (aAtom1 == aAtom2) {
+    return true;
+  }
+
+  // If both are ascii lowercase already, we know that the slow comparison
+  // below is going to return false.
+  if (aAtom1->IsAsciiLowercase() && aAtom2->IsAsciiLowercase()) {
+    return false;
+  }
+
+  return EqualsIgnoreASCIICase(nsDependentAtomString(aAtom1),
+                               nsDependentAtomString(aAtom2));
+}
+
+/* static */
+bool nsContentUtils::EqualsIgnoreASCIICase(const nsAString& aStr1,
+                                           const nsAString& aStr2) {
+  uint32_t len = aStr1.Length();
+  if (len != aStr2.Length()) {
+    return false;
+  }
+
+  const char16_t* str1 = aStr1.BeginReading();
+  const char16_t* str2 = aStr2.BeginReading();
+  const char16_t* end = str1 + len;
+
+  while (str1 < end) {
+    char16_t c1 = *str1++;
+    char16_t c2 = *str2++;
+
+    // First check if any bits other than the 0x0020 differs
+    if ((c1 ^ c2) & 0xffdf) {
+      return false;
+    }
+
+    // We know they can only differ in the 0x0020 bit.
+    // Likely the two chars are the same, so check that first
+    if (c1 != c2) {
+      // They do differ, but since it's only in the 0x0020 bit, check if it's
+      // the same ascii char, but just differing in case
+      char16_t c1Upper = c1 & 0xffdf;
+      if (!('A' <= c1Upper && c1Upper <= 'Z')) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+/* static */
+bool nsContentUtils::StringContainsASCIIUpper(const nsAString& aStr) {
+  const char16_t* iter = aStr.BeginReading();
+  const char16_t* end = aStr.EndReading();
+  while (iter != end) {
+    char16_t c = *iter;
+    if (c >= 'A' && c <= 'Z') {
+      return true;
+    }
+    ++iter;
+  }
+
+  return false;
+}
+
+/* static */
+nsIInterfaceRequestor* nsContentUtils::SameOriginChecker() {
+  if (!sSameOriginChecker) {
+    sSameOriginChecker = new SameOriginCheckerImpl();
+    NS_ADDREF(sSameOriginChecker);
+  }
+  return sSameOriginChecker;
+}
+
+/* static */
+nsresult nsContentUtils::CheckSameOrigin(nsIChannel* aOldChannel,
+                                         nsIChannel* aNewChannel) {
+  if (!nsContentUtils::GetSecurityManager()) return NS_ERROR_NOT_AVAILABLE;
+
+  nsCOMPtr<nsIPrincipal> oldPrincipal;
+  nsContentUtils::GetSecurityManager()->GetChannelResultPrincipal(
+      aOldChannel, getter_AddRefs(oldPrincipal));
+
+  nsCOMPtr<nsIURI> newURI;
+  aNewChannel->GetURI(getter_AddRefs(newURI));
+  nsCOMPtr<nsIURI> newOriginalURI;
+  aNewChannel->GetOriginalURI(getter_AddRefs(newOriginalURI));
+
+  NS_ENSURE_STATE(oldPrincipal && newURI && newOriginalURI);
+
+  nsresult rv = oldPrincipal->CheckMayLoad(newURI, false);
+  if (NS_SUCCEEDED(rv) && newOriginalURI != newURI) {
+    rv = oldPrincipal->CheckMayLoad(newOriginalURI, false);
+  }
+
+  return rv;
+}
+
+NS_IMPL_ISUPPORTS(SameOriginCheckerImpl, nsIChannelEventSink,
+                  nsIInterfaceRequestor)
+
+NS_IMETHODIMP
+SameOriginCheckerImpl::AsyncOnChannelRedirect(
+    nsIChannel* aOldChannel, nsIChannel* aNewChannel, uint32_t aFlags,
+    nsIAsyncVerifyRedirectCallback* cb) {
+  MOZ_ASSERT(aNewChannel, "Redirecting to null channel?");
+
+  nsresult rv = nsContentUtils::CheckSameOrigin(aOldChannel, aNewChannel);
+  if (NS_SUCCEEDED(rv)) {
+    cb->OnRedirectVerifyCallback(NS_OK);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+SameOriginCheckerImpl::GetInterface(const nsIID& aIID, void** aResult) {
+  return QueryInterface(aIID, aResult);
+}
+
+/* static */
+nsresult nsContentUtils::GetASCIIOrigin(nsIURI* aURI, nsACString& aOrigin) {
+  MOZ_ASSERT(aURI, "missing uri");
+
+  // For Blob URI, the path is the URL of the owning page.
+  if (aURI->SchemeIs(BLOBURI_SCHEME)) {
+    nsAutoCString path;
+    nsresult rv = aURI->GetPathQueryRef(path);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    nsCOMPtr<nsIURI> uri;
+    rv = NS_NewURI(getter_AddRefs(uri), path);
+    if (NS_FAILED(rv)) {
+      aOrigin.AssignLiteral("null");
+      return NS_OK;
+    }
+
+    return GetASCIIOrigin(uri, aOrigin);
+  }
+
+  aOrigin.Truncate();
+
+  nsCOMPtr<nsIURI> uri = NS_GetInnermostURI(aURI);
+  NS_ENSURE_TRUE(uri, NS_ERROR_UNEXPECTED);
+
+  nsAutoCString host;
+  nsresult rv = uri->GetAsciiHost(host);
+
+  if (NS_SUCCEEDED(rv) && !host.IsEmpty()) {
+    nsAutoCString userPass;
+    uri->GetUserPass(userPass);
+
+    nsAutoCString prePath;
+    if (!userPass.IsEmpty()) {
+      rv = NS_MutateURI(uri).SetUserPass(""_ns).Finalize(uri);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+
+    rv = uri->GetPrePath(prePath);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    aOrigin = prePath;
+  } else {
+    aOrigin.AssignLiteral("null");
+  }
+
+  return NS_OK;
+}
+
+/* static */
+nsresult nsContentUtils::GetUTFOrigin(nsIPrincipal* aPrincipal,
+                                      nsAString& aOrigin) {
+  MOZ_ASSERT(aPrincipal, "missing principal");
+
+  aOrigin.Truncate();
+  nsAutoCString asciiOrigin;
+
+  nsresult rv = aPrincipal->GetAsciiOrigin(asciiOrigin);
+  if (NS_FAILED(rv)) {
+    asciiOrigin.AssignLiteral("null");
+  }
+
+  CopyUTF8toUTF16(asciiOrigin, aOrigin);
+  return NS_OK;
+}
+
+/* static */
+nsresult nsContentUtils::GetUTFOrigin(nsIURI* aURI, nsAString& aOrigin) {
+  MOZ_ASSERT(aURI, "missing uri");
+  nsresult rv;
+
+#if defined(MOZ_THUNDERBIRD) || defined(MOZ_SUITE)
+  // Check if either URI has a special origin.
+  nsCOMPtr<nsIURIWithSpecialOrigin> uriWithSpecialOrigin =
+      do_QueryInterface(aURI);
+  if (uriWithSpecialOrigin) {
+    nsCOMPtr<nsIURI> origin;
+    rv = uriWithSpecialOrigin->GetOrigin(getter_AddRefs(origin));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    return GetUTFOrigin(origin, aOrigin);
+  }
+#endif
+
+  nsAutoCString asciiOrigin;
+  rv = GetASCIIOrigin(aURI, asciiOrigin);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  CopyUTF8toUTF16(asciiOrigin, aOrigin);
+  return NS_OK;
+}
+
+/* static */
+bool nsContentUtils::CheckMayLoad(nsIPrincipal* aPrincipal,
+                                  nsIChannel* aChannel,
+                                  bool aAllowIfInheritsPrincipal) {
+  nsCOMPtr<nsIURI> channelURI;
+  nsresult rv = NS_GetFinalChannelURI(aChannel, getter_AddRefs(channelURI));
+  NS_ENSURE_SUCCESS(rv, false);
+
+  return NS_SUCCEEDED(
+      aPrincipal->CheckMayLoad(channelURI, aAllowIfInheritsPrincipal));
+}
+
+/* static */
+bool nsContentUtils::CanAccessNativeAnon() {
+  return LegacyIsCallerChromeOrNativeCode();
+}
+
+/* static */
+nsresult nsContentUtils::DispatchXULCommand(nsIContent* aTarget, bool aTrusted,
+                                            Event* aSourceEvent,
+                                            PresShell* aPresShell, bool aCtrl,
+                                            bool aAlt, bool aShift, bool aMeta,
+                                            uint16_t aInputSource,
+                                            int16_t aButton) {
+  NS_ENSURE_STATE(aTarget);
+  Document* doc = aTarget->OwnerDoc();
+  nsPresContext* presContext = doc->GetPresContext();
+
+  RefPtr<XULCommandEvent> xulCommand =
+      new XULCommandEvent(doc, presContext, nullptr);
+  xulCommand->InitCommandEvent(u"command"_ns, true, true,
+                               nsGlobalWindowInner::Cast(doc->GetInnerWindow()),
+                               0, aCtrl, aAlt, aShift, aMeta, aButton,
+                               aSourceEvent, aInputSource, IgnoreErrors());
+
+  if (aPresShell) {
+    nsEventStatus status = nsEventStatus_eIgnore;
+    return aPresShell->HandleDOMEventWithTarget(aTarget, xulCommand, &status);
+  }
+
+  ErrorResult rv;
+  aTarget->DispatchEvent(*xulCommand, rv);
+  return rv.StealNSResult();
+}
+
+// static
+nsresult nsContentUtils::WrapNative(JSContext* cx, nsISupports* native,
+                                    nsWrapperCache* cache, const nsIID* aIID,
+                                    JS::MutableHandle<JS::Value> vp,
+                                    bool aAllowWrapping) {
+  MOZ_ASSERT(cx == GetCurrentJSContext());
+
+  if (!native) {
+    vp.setNull();
+
+    return NS_OK;
+  }
+
+  JSObject* wrapper = xpc_FastGetCachedWrapper(cx, cache, vp);
+  if (wrapper) {
+    return NS_OK;
+  }
+
+  NS_ENSURE_TRUE(sXPConnect, NS_ERROR_UNEXPECTED);
+
+  if (!NS_IsMainThread()) {
+    MOZ_CRASH();
+  }
+
+  JS::Rooted<JSObject*> scope(cx, JS::CurrentGlobalOrNull(cx));
+  nsresult rv = sXPConnect->WrapNativeToJSVal(cx, scope, native, cache, aIID,
+                                              aAllowWrapping, vp);
+  return rv;
+}
+
+nsresult nsContentUtils::CreateArrayBuffer(JSContext* aCx,
+                                           const nsACString& aData,
+                                           JSObject** aResult) {
+  if (!aCx) {
+    return NS_ERROR_FAILURE;
+  }
+
+  size_t dataLen = aData.Length();
+  *aResult = JS::NewArrayBuffer(aCx, dataLen);
+  if (!*aResult) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (dataLen > 0) {
+    NS_ASSERTION(JS::IsArrayBufferObject(*aResult), "What happened?");
+    JS::AutoCheckCannotGC nogc;
+    bool isShared;
+    memcpy(JS::GetArrayBufferData(*aResult, &isShared, nogc),
+           aData.BeginReading(), dataLen);
+    MOZ_ASSERT(!isShared);
+  }
+
+  return NS_OK;
+}
+
+void nsContentUtils::StripNullChars(const nsAString& aInStr,
+                                    nsAString& aOutStr) {
+  // In common cases where we don't have nulls in the
+  // string we can simple simply bypass the checking code.
+  int32_t firstNullPos = aInStr.FindChar('\0');
+  if (firstNullPos == kNotFound) {
+    aOutStr.Assign(aInStr);
+    return;
+  }
+
+  aOutStr.SetCapacity(aInStr.Length() - 1);
+  nsAString::const_iterator start, end;
+  aInStr.BeginReading(start);
+  aInStr.EndReading(end);
+  while (start != end) {
+    if (*start != '\0') aOutStr.Append(*start);
+    ++start;
+  }
+}
+
+struct ClassMatchingInfo {
+  AtomArray mClasses;
+  nsCaseTreatment mCaseTreatment;
+};
+
+// static
+bool nsContentUtils::MatchClassNames(Element* aElement, int32_t aNamespaceID,
+                                     nsAtom* aAtom, void* aData) {
+  // We can't match if there are no class names
+  const nsAttrValue* classAttr = aElement->GetClasses();
+  if (!classAttr) {
+    return false;
+  }
+
+  // need to match *all* of the classes
+  ClassMatchingInfo* info = static_cast<ClassMatchingInfo*>(aData);
+  uint32_t length = info->mClasses.Length();
+  if (!length) {
+    // If we actually had no classes, don't match.
+    return false;
+  }
+  uint32_t i;
+  for (i = 0; i < length; ++i) {
+    if (!classAttr->Contains(info->mClasses[i], info->mCaseTreatment)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+// static
+void nsContentUtils::DestroyClassNameArray(void* aData) {
+  ClassMatchingInfo* info = static_cast<ClassMatchingInfo*>(aData);
+  delete info;
+}
+
+// static
+void* nsContentUtils::AllocClassMatchingInfo(nsINode* aRootNode,
+                                             const nsString* aClasses) {
+  nsAttrValue attrValue;
+  attrValue.ParseAtomArray(*aClasses);
+  // nsAttrValue::Equals is sensitive to order, so we'll send an array
+  auto* info = new ClassMatchingInfo;
+  if (attrValue.Type() == nsAttrValue::eAtomArray) {
+    info->mClasses = std::move(attrValue.GetAtomArrayValue()->mArray);
+  } else if (attrValue.Type() == nsAttrValue::eAtom) {
+    info->mClasses.AppendElement(attrValue.GetAtomValue());
+  }
+
+  info->mCaseTreatment =
+      aRootNode->OwnerDoc()->GetCompatibilityMode() == eCompatibility_NavQuirks
+          ? eIgnoreCase
+          : eCaseMatters;
+  return info;
+}
+
+// static
+bool nsContentUtils::IsFocusedContent(const nsIContent* aContent) {
+  nsFocusManager* fm = nsFocusManager::GetFocusManager();
+
+  return fm && fm->GetFocusedElement() == aContent;
+}
+
+bool nsContentUtils::HasScrollgrab(nsIContent* aContent) {
+  // If we ever standardize this feature we'll want to hook this up properly
+  // again. For now we're removing all the DOM-side code related to it but
+  // leaving the layout and APZ handling for it in place.
+  return false;
+}
+
+void nsContentUtils::FlushLayoutForTree(nsPIDOMWindowOuter* aWindow) {
+  if (!aWindow) {
+    return;
+  }
+
+  // Note that because FlushPendingNotifications flushes parents, this
+  // is O(N^2) in docshell tree depth.  However, the docshell tree is
+  // usually pretty shallow.
+
+  if (RefPtr<Document> doc = aWindow->GetDoc()) {
+    doc->FlushPendingNotifications(FlushType::Layout);
+  }
+
+  if (nsCOMPtr<nsIDocShell> docShell = aWindow->GetDocShell()) {
+    int32_t i = 0, i_end;
+    docShell->GetInProcessChildCount(&i_end);
+    for (; i < i_end; ++i) {
+      nsCOMPtr<nsIDocShellTreeItem> item;
+      if (docShell->GetInProcessChildAt(i, getter_AddRefs(item)) == NS_OK &&
+          item) {
+        if (nsCOMPtr<nsPIDOMWindowOuter> win = item->GetWindow()) {
+          FlushLayoutForTree(win);
+        }
+      }
+    }
+  }
+}
+
+void nsContentUtils::RemoveNewlines(nsString& aString) { aString.StripCRLF(); }
+
+void nsContentUtils::PlatformToDOMLineBreaks(nsString& aString) {
+  if (!PlatformToDOMLineBreaks(aString, fallible)) {
+    aString.AllocFailed(aString.Length());
+  }
+}
+
+bool nsContentUtils::PlatformToDOMLineBreaks(nsString& aString,
+                                             const fallible_t& aFallible) {
+  if (aString.FindChar(char16_t('\r')) != -1) {
+    // Windows linebreaks: Map CRLF to LF:
+    if (!aString.ReplaceSubstring(u"\r\n", u"\n", aFallible)) {
+      return false;
+    }
+
+    // Mac linebreaks: Map any remaining CR to LF:
+    if (!aString.ReplaceSubstring(u"\r", u"\n", aFallible)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+void nsContentUtils::PopulateStringFromStringBuffer(nsStringBuffer* aBuf,
+                                                    nsAString& aResultString) {
+  MOZ_ASSERT(aBuf, "Expecting a non-null string buffer");
+
+  uint32_t stringLen = NS_strlen(static_cast<char16_t*>(aBuf->Data()));
+
+  // SANITY CHECK: In case the nsStringBuffer isn't correctly
+  // null-terminated, let's clamp its length using the allocated size, to be
+  // sure the resulting string doesn't sample past the end of the the buffer.
+  // (Note that StorageSize() is in units of bytes, so we have to convert that
+  // to units of PRUnichars, and subtract 1 for the null-terminator.)
+  uint32_t allocStringLen = (aBuf->StorageSize() / sizeof(char16_t)) - 1;
+  MOZ_ASSERT(stringLen <= allocStringLen,
+             "string buffer lacks null terminator!");
+  stringLen = std::min(stringLen, allocStringLen);
+
+  aBuf->ToString(stringLen, aResultString);
+}
+
+already_AddRefed<nsContentList> nsContentUtils::GetElementsByClassName(
+    nsINode* aRootNode, const nsAString& aClasses) {
+  MOZ_ASSERT(aRootNode, "Must have root node");
+
+  return GetFuncStringContentList<nsCacheableFuncStringHTMLCollection>(
+      aRootNode, MatchClassNames, DestroyClassNameArray, AllocClassMatchingInfo,
+      aClasses);
+}
+
+PresShell* nsContentUtils::FindPresShellForDocument(const Document* aDocument) {
+  const Document* doc = aDocument;
+  Document* displayDoc = doc->GetDisplayDocument();
+  if (displayDoc) {
+    doc = displayDoc;
+  }
+
+  PresShell* presShell = doc->GetPresShell();
+  if (presShell) {
+    return presShell;
+  }
+
+  nsCOMPtr<nsIDocShellTreeItem> docShellTreeItem = doc->GetDocShell();
+  while (docShellTreeItem) {
+    // We may be in a display:none subdocument, or we may not have a presshell
+    // created yet.
+    // Walk the docshell tree to find the nearest container that has a
+    // presshell, and return that.
+    nsCOMPtr<nsIDocShell> docShell = do_QueryInterface(docShellTreeItem);
+    if (PresShell* presShell = docShell->GetPresShell()) {
+      return presShell;
+    }
+    nsCOMPtr<nsIDocShellTreeItem> parent;
+    docShellTreeItem->GetInProcessParent(getter_AddRefs(parent));
+    docShellTreeItem = parent;
+  }
+
+  return nullptr;
+}
+
+/* static */
+nsPresContext* nsContentUtils::FindPresContextForDocument(
+    const Document* aDocument) {
+  if (PresShell* presShell = FindPresShellForDocument(aDocument)) {
+    return presShell->GetPresContext();
+  }
+  return nullptr;
+}
+
+nsIWidget* nsContentUtils::WidgetForDocument(const Document* aDocument) {
+  PresShell* presShell = FindPresShellForDocument(aDocument);
+  if (!presShell) {
+    return nullptr;
+  }
+  nsViewManager* vm = presShell->GetViewManager();
+  if (!vm) {
+    return nullptr;
+  }
+  nsView* rootView = vm->GetRootView();
+  if (!rootView) {
+    return nullptr;
+  }
+  nsView* displayRoot = nsViewManager::GetDisplayRootFor(rootView);
+  if (!displayRoot) {
+    return nullptr;
+  }
+  return displayRoot->GetNearestWidget(nullptr);
+}
+
+nsIWidget* nsContentUtils::WidgetForContent(const nsIContent* aContent) {
+  nsIFrame* frame = aContent->GetPrimaryFrame();
+  if (frame) {
+    frame = nsLayoutUtils::GetDisplayRootFrame(frame);
+
+    nsView* view = frame->GetView();
+    if (view) {
+      return view->GetWidget();
+    }
+  }
+
+  return nullptr;
+}
+
+WindowRenderer* nsContentUtils::WindowRendererForContent(
+    const nsIContent* aContent) {
+  nsIWidget* widget = nsContentUtils::WidgetForContent(aContent);
+  if (widget) {
+    return widget->GetWindowRenderer();
+  }
+
+  return nullptr;
+}
+
+WindowRenderer* nsContentUtils::WindowRendererForDocument(
+    const Document* aDoc) {
+  nsIWidget* widget = nsContentUtils::WidgetForDocument(aDoc);
+  if (widget) {
+    return widget->GetWindowRenderer();
+  }
+
+  return nullptr;
+}
+
+bool nsContentUtils::AllowXULXBLForPrincipal(nsIPrincipal* aPrincipal) {
+  if (!aPrincipal) {
+    return false;
+  }
+
+  if (aPrincipal->IsSystemPrincipal()) {
+    return true;
+  }
+
+  return (StaticPrefs::dom_allow_XUL_XBL_for_file() &&
+          aPrincipal->SchemeIs("file")) ||
+         IsSitePermAllow(aPrincipal, "allowXULXBL"_ns);
+}
+
+bool nsContentUtils::IsPDFJSEnabled() {
+  nsCOMPtr<nsIStreamConverter> conv = do_CreateInstance(
+      "@mozilla.org/streamconv;1?from=application/pdf&to=text/html");
+  return conv;
+}
+
+bool nsContentUtils::IsPDFJS(nsIPrincipal* aPrincipal) {
+  if (!aPrincipal) {
+    return false;
+  }
+  nsAutoCString spec;
+  nsresult rv = aPrincipal->GetAsciiSpec(spec);
+  NS_ENSURE_SUCCESS(rv, false);
+  return spec.EqualsLiteral("resource://pdf.js/web/viewer.html");
+}
+
+bool nsContentUtils::IsSystemOrPDFJS(JSContext* aCx, JSObject*) {
+  nsIPrincipal* principal = SubjectPrincipal(aCx);
+  return principal && (principal->IsSystemPrincipal() || IsPDFJS(principal));
+}
+
+already_AddRefed<nsIDocumentLoaderFactory>
+nsContentUtils::FindInternalContentViewer(const nsACString& aType,
+                                          ContentViewerType* aLoaderType) {
+  if (aLoaderType) {
+    *aLoaderType = TYPE_UNSUPPORTED;
+  }
+
+  // one helper factory, please
+  nsCOMPtr<nsICategoryManager> catMan(
+      do_GetService(NS_CATEGORYMANAGER_CONTRACTID));
+  if (!catMan) return nullptr;
+
+  nsCOMPtr<nsIDocumentLoaderFactory> docFactory;
+
+  nsCString contractID;
+  nsresult rv =
+      catMan->GetCategoryEntry("Gecko-Content-Viewers", aType, contractID);
+  if (NS_SUCCEEDED(rv)) {
+    docFactory = do_GetService(contractID.get());
+    if (docFactory && aLoaderType) {
+      if (contractID.EqualsLiteral(CONTENT_DLF_CONTRACTID))
+        *aLoaderType = TYPE_CONTENT;
+      else if (contractID.EqualsLiteral(PLUGIN_DLF_CONTRACTID))
+        *aLoaderType = TYPE_FALLBACK;
+      else
+        *aLoaderType = TYPE_UNKNOWN;
+    }
+    return docFactory.forget();
+  }
+
+  if (DecoderTraits::IsSupportedInVideoDocument(aType)) {
+    docFactory =
+        do_GetService("@mozilla.org/content/document-loader-factory;1");
+    if (docFactory && aLoaderType) {
+      *aLoaderType = TYPE_CONTENT;
+    }
+    return docFactory.forget();
+  }
+
+  return nullptr;
+}
+
+static void ReportPatternCompileFailure(nsAString& aPattern,
+                                        const Document* aDocument,
+                                        JS::MutableHandle<JS::Value> error,
+                                        JSContext* cx) {
+  JS::AutoSaveExceptionState savedExc(cx);
+  JS::Rooted<JSObject*> exnObj(cx, &error.toObject());
+  JS::Rooted<JS::Value> messageVal(cx);
+  if (!JS_GetProperty(cx, exnObj, "message", &messageVal)) {
+    return;
+  }
+  JS::Rooted<JSString*> messageStr(cx, messageVal.toString());
+  MOZ_ASSERT(messageStr);
+
+  AutoTArray<nsString, 2> strings;
+  strings.AppendElement(aPattern);
+  if (!AssignJSString(cx, *strings.AppendElement(), messageStr)) {
+    return;
+  }
+
+  nsContentUtils::ReportToConsole(nsIScriptError::errorFlag, "DOM"_ns,
+                                  aDocument, nsContentUtils::eDOM_PROPERTIES,
+                                  "PatternAttributeCompileFailure", strings);
+  savedExc.drop();
+}
+
+// static
+Maybe<bool> nsContentUtils::IsPatternMatching(nsAString& aValue,
+                                              nsAString& aPattern,
+                                              const Document* aDocument,
+                                              bool aHasMultiple) {
+  NS_ASSERTION(aDocument, "aDocument should be a valid pointer (not null)");
+
+  // The fact that we're using a JS regexp under the hood should not be visible
+  // to things like window onerror handlers, so we don't initialize our JSAPI
+  // with the document's window (which may not exist anyway).
+  AutoJSAPI jsapi;
+  jsapi.Init();
+  JSContext* cx = jsapi.cx();
+  AutoDisableJSInterruptCallback disabler(cx);
+
+  // We can use the junk scope here, because we're just using it for regexp
+  // evaluation, not actual script execution, and we disable statics so that the
+  // evaluation does not interact with the execution global.
+  JSAutoRealm ar(cx, xpc::PrivilegedJunkScope());
+
+  // Check if the pattern by itself is valid first, and not that it only becomes
+  // valid once we add ^(?: and )$.
+  JS::Rooted<JS::Value> error(cx);
+  if (!JS::CheckRegExpSyntax(
+          cx, static_cast<char16_t*>(aPattern.BeginWriting()),
+          aPattern.Length(), JS::RegExpFlag::Unicode, &error)) {
+    return Nothing();
+  }
+
+  if (!error.isUndefined()) {
+    ReportPatternCompileFailure(aPattern, aDocument, &error, cx);
+    return Some(true);
+  }
+
+  // The pattern has to match the entire value.
+  aPattern.InsertLiteral(u"^(?:", 0);
+  aPattern.AppendLiteral(")$");
+
+  JS::Rooted<JSObject*> re(
+      cx,
+      JS::NewUCRegExpObject(cx, static_cast<char16_t*>(aPattern.BeginWriting()),
+                            aPattern.Length(), JS::RegExpFlag::Unicode));
+  if (!re) {
+    return Nothing();
+  }
+
+  JS::Rooted<JS::Value> rval(cx, JS::NullValue());
+  if (!aHasMultiple) {
+    size_t idx = 0;
+    if (!JS::ExecuteRegExpNoStatics(
+            cx, re, static_cast<char16_t*>(aValue.BeginWriting()),
+            aValue.Length(), &idx, true, &rval)) {
+      return Nothing();
+    }
+    return Some(!rval.isNull());
+  }
+
+  HTMLSplitOnSpacesTokenizer tokenizer(aValue, ',');
+  while (tokenizer.hasMoreTokens()) {
+    const nsAString& value = tokenizer.nextToken();
+    size_t idx = 0;
+    if (!JS::ExecuteRegExpNoStatics(
+            cx, re, static_cast<const char16_t*>(value.BeginReading()),
+            value.Length(), &idx, true, &rval)) {
+      return Nothing();
+    }
+    if (rval.isNull()) {
+      return Some(false);
+    }
+  }
+  return Some(true);
+}
+
+// static
+nsresult nsContentUtils::URIInheritsSecurityContext(nsIURI* aURI,
+                                                    bool* aResult) {
+  // Note: about:blank URIs do NOT inherit the security context from the
+  // current document, which is what this function tests for...
+  return NS_URIChainHasFlags(
+      aURI, nsIProtocolHandler::URI_INHERITS_SECURITY_CONTEXT, aResult);
+}
+
+// static
+bool nsContentUtils::ChannelShouldInheritPrincipal(
+    nsIPrincipal* aLoadingPrincipal, nsIURI* aURI, bool aInheritForAboutBlank,
+    bool aForceInherit) {
+  MOZ_ASSERT(aLoadingPrincipal,
+             "Can not check inheritance without a principal");
+
+  // Only tell the channel to inherit if it can't provide its own security
+  // context.
+  //
+  // XXX: If this is ever changed, check all callers for what owners
+  //      they're passing in.  In particular, see the code and
+  //      comments in nsDocShell::LoadURI where we fall back on
+  //      inheriting the owner if called from chrome.  That would be
+  //      very wrong if this code changed anything but channels that
+  //      can't provide their own security context!
+  //
+  // If aForceInherit is true, we will inherit, even for a channel that
+  // can provide its own security context. This is used for srcdoc loads.
+  bool inherit = aForceInherit;
+  if (!inherit) {
+    bool uriInherits;
+    // We expect URIInheritsSecurityContext to return success for an
+    // about:blank URI, so don't call NS_IsAboutBlank() if this call fails.
+    // This condition needs to match the one in nsDocShell::InternalLoad where
+    // we're checking for things that will use the owner.
+    inherit =
+        (NS_SUCCEEDED(URIInheritsSecurityContext(aURI, &uriInherits)) &&
+         (uriInherits || (aInheritForAboutBlank && NS_IsAboutBlank(aURI)))) ||
+        //
+        // file: uri special-casing
+        //
+        // If this is a file: load opened from another file: then it may need
+        // to inherit the owner from the referrer so they can script each other.
+        // If we don't set the owner explicitly then each file: gets an owner
+        // based on its own codebase later.
+        //
+        (URIIsLocalFile(aURI) &&
+         NS_SUCCEEDED(aLoadingPrincipal->CheckMayLoad(aURI, false)) &&
+         // One more check here.  CheckMayLoad will always return true for the
+         // system principal, but we do NOT want to inherit in that case.
+         !aLoadingPrincipal->IsSystemPrincipal());
+  }
+  return inherit;
+}
+
+/* static */
+bool nsContentUtils::IsCutCopyAllowed(Document* aDocument,
+                                      nsIPrincipal& aSubjectPrincipal) {
+  if (StaticPrefs::dom_allow_cut_copy() && aDocument &&
+      aDocument->HasValidTransientUserGestureActivation()) {
+    return true;
+  }
+
+  return PrincipalHasPermission(aSubjectPrincipal, nsGkAtoms::clipboardWrite);
+}
+
+/* static */
+bool nsContentUtils::HaveEqualPrincipals(Document* aDoc1, Document* aDoc2) {
+  if (!aDoc1 || !aDoc2) {
+    return false;
+  }
+  bool principalsEqual = false;
+  aDoc1->NodePrincipal()->Equals(aDoc2->NodePrincipal(), &principalsEqual);
+  return principalsEqual;
+}
+
+/* static */
+bool nsContentUtils::HasPluginWithUncontrolledEventDispatch(
+    nsIContent* aContent) {
+  return false;
+}
+
+/* static */
+void nsContentUtils::FireMutationEventsForDirectParsing(
+    Document* aDoc, nsIContent* aDest, int32_t aOldChildCount) {
+  // Fire mutation events. Optimize for the case when there are no listeners
+  int32_t newChildCount = aDest->GetChildCount();
+  if (newChildCount && nsContentUtils::HasMutationListeners(
+                           aDoc, NS_EVENT_BITS_MUTATION_NODEINSERTED)) {
+    AutoTArray<nsCOMPtr<nsIContent>, 50> childNodes;
+    NS_ASSERTION(newChildCount - aOldChildCount >= 0,
+                 "What, some unexpected dom mutation has happened?");
+    childNodes.SetCapacity(newChildCount - aOldChildCount);
+    for (nsIContent* child = aDest->GetFirstChild(); child;
+         child = child->GetNextSibling()) {
+      childNodes.AppendElement(child);
+    }
+    FragmentOrElement::FireNodeInserted(aDoc, aDest, childNodes);
+  }
+}
+
+/* static */
+const Document* nsContentUtils::GetInProcessSubtreeRootDocument(
+    const Document* aDoc) {
+  if (!aDoc) {
+    return nullptr;
+  }
+  const Document* doc = aDoc;
+  while (doc->GetInProcessParentDocument()) {
+    doc = doc->GetInProcessParentDocument();
+  }
+  return doc;
+}
+
+// static
+int32_t nsContentUtils::GetAdjustedOffsetInTextControl(nsIFrame* aOffsetFrame,
+                                                       int32_t aOffset) {
+  // The structure of the anonymous frames within a text control frame is
+  // an optional block frame, followed by an optional br frame.
+
+  // If the offset frame has a child, then this frame is the block which
+  // has the text frames (containing the content) as its children. This will
+  // be the case if we click to the right of any of the text frames, or at the
+  // bottom of the text area.
+  nsIFrame* firstChild = aOffsetFrame->PrincipalChildList().FirstChild();
+  if (firstChild) {
+    // In this case, the passed-in offset is incorrect, and we want the length
+    // of the entire content in the text control frame.
+    return firstChild->GetContent()->Length();
+  }
+
+  if (aOffsetFrame->GetPrevSibling() && !aOffsetFrame->GetNextSibling()) {
+    // In this case, we're actually within the last frame, which is a br
+    // frame. Our offset should therefore be the length of the first child of
+    // our parent.
+    int32_t aOutOffset = aOffsetFrame->GetParent()
+                             ->PrincipalChildList()
+                             .FirstChild()
+                             ->GetContent()
+                             ->Length();
+    return aOutOffset;
+  }
+
+  // Otherwise, we're within one of the text frames, in which case our offset
+  // has already been correctly calculated.
+  return aOffset;
+}
+
+// static
+void nsContentUtils::GetSelectionInTextControl(Selection* aSelection,
+                                               Element* aRoot,
+                                               uint32_t& aOutStartOffset,
+                                               uint32_t& aOutEndOffset) {
+  MOZ_ASSERT(aSelection && aRoot);
+
+  // We don't care which end of this selection is anchor and which is focus.  In
+  // fact, we explicitly want to know which is the _start_ and which is the
+  // _end_, not anchor vs focus.
+  const nsRange* range = aSelection->GetAnchorFocusRange();
+  if (!range) {
+    // Nothing selected
+    aOutStartOffset = aOutEndOffset = 0;
+    return;
+  }
+
+  // All the node pointers here are raw pointers for performance.  We shouldn't
+  // be doing anything in this function that invalidates the node tree.
+  nsINode* startContainer = range->GetStartContainer();
+  uint32_t startOffset = range->StartOffset();
+  nsINode* endContainer = range->GetEndContainer();
+  uint32_t endOffset = range->EndOffset();
+
+  // We have at most two children, consisting of an optional text node followed
+  // by an optional <br>.
+  NS_ASSERTION(aRoot->GetChildCount() <= 2, "Unexpected children");
+  nsIContent* firstChild = aRoot->GetFirstChild();
+#ifdef DEBUG
+  nsCOMPtr<nsIContent> lastChild = aRoot->GetLastChild();
+  NS_ASSERTION(startContainer == aRoot || startContainer == firstChild ||
+                   startContainer == lastChild,
+               "Unexpected startContainer");
+  NS_ASSERTION(endContainer == aRoot || endContainer == firstChild ||
+                   endContainer == lastChild,
+               "Unexpected endContainer");
+  // firstChild is either text or a <br> (hence an element).
+  MOZ_ASSERT_IF(firstChild, firstChild->IsText() || firstChild->IsElement());
+#endif
+  if (!firstChild || firstChild->IsElement()) {
+    // No text node, so everything is 0
+    startOffset = endOffset = 0;
+  } else {
+    // First child is text.  If the start/end is already in the text node,
+    // or the start of the root node, no change needed.  If it's in the root
+    // node but not the start, or in the trailing <br>, we need to set the
+    // offset to the end.
+    if ((startContainer == aRoot && startOffset != 0) ||
+        (startContainer != aRoot && startContainer != firstChild)) {
+      startOffset = firstChild->Length();
+    }
+    if ((endContainer == aRoot && endOffset != 0) ||
+        (endContainer != aRoot && endContainer != firstChild)) {
+      endOffset = firstChild->Length();
+    }
+  }
+
+  MOZ_ASSERT(startOffset <= endOffset);
+  aOutStartOffset = startOffset;
+  aOutEndOffset = endOffset;
+}
+
+// static
+HTMLEditor* nsContentUtils::GetHTMLEditor(nsPresContext* aPresContext) {
+  if (!aPresContext) {
+    return nullptr;
+  }
+  return GetHTMLEditor(aPresContext->GetDocShell());
+}
+
+// static
+HTMLEditor* nsContentUtils::GetHTMLEditor(nsDocShell* aDocShell) {
+  bool isEditable;
+  if (!aDocShell || NS_FAILED(aDocShell->GetEditable(&isEditable)) ||
+      !isEditable) {
+    return nullptr;
+  }
+  return aDocShell->GetHTMLEditor();
+}
+
+// static
+EditorBase* nsContentUtils::GetActiveEditor(nsPresContext* aPresContext) {
+  if (!aPresContext) {
+    return nullptr;
+  }
+
+  return GetActiveEditor(aPresContext->Document()->GetWindow());
+}
+
+// static
+EditorBase* nsContentUtils::GetActiveEditor(nsPIDOMWindowOuter* aWindow) {
+  if (!aWindow || !aWindow->GetExtantDoc()) {
+    return nullptr;
+  }
+
+  // If it's in designMode, nobody can have focus.  Therefore, the HTMLEditor
+  // handles all events.  I.e., it's focused editor in this case.
+  if (aWindow->GetExtantDoc()->IsInDesignMode()) {
+    return GetHTMLEditor(nsDocShell::Cast(aWindow->GetDocShell()));
+  }
+
+  // If focused element is associated with TextEditor, it must be <input>
+  // element or <textarea> element.  Let's return it even if it's in a
+  // contenteditable element.
+  nsCOMPtr<nsPIDOMWindowOuter> focusedWindow;
+  if (Element* focusedElement = nsFocusManager::GetFocusedDescendant(
+          aWindow, nsFocusManager::SearchRange::eOnlyCurrentWindow,
+          getter_AddRefs(focusedWindow))) {
+    if (TextEditor* textEditor = focusedElement->GetTextEditorInternal()) {
+      return textEditor;
+    }
+  }
+
+  // Otherwise, HTMLEditor may handle inputs even non-editable element has
+  // focus or nobody has focus.
+  return GetHTMLEditor(nsDocShell::Cast(aWindow->GetDocShell()));
+}
+
+// static
+TextEditor* nsContentUtils::GetTextEditorFromAnonymousNodeWithoutCreation(
+    const nsIContent* aAnonymousContent) {
+  if (!aAnonymousContent) {
+    return nullptr;
+  }
+  nsIContent* parent = aAnonymousContent->FindFirstNonChromeOnlyAccessContent();
+  if (!parent || parent == aAnonymousContent) {
+    return nullptr;
+  }
+  if (HTMLInputElement* inputElement =
+          HTMLInputElement::FromNodeOrNull(parent)) {
+    return inputElement->GetTextEditorWithoutCreation();
+  }
+  if (HTMLTextAreaElement* textareaElement =
+          HTMLTextAreaElement::FromNodeOrNull(parent)) {
+    return textareaElement->GetTextEditorWithoutCreation();
+  }
+  return nullptr;
+}
+
+// static
+bool nsContentUtils::IsNodeInEditableRegion(nsINode* aNode) {
+  while (aNode) {
+    if (aNode->IsEditable()) {
+      return true;
+    }
+    aNode = aNode->GetParent();
+  }
+  return false;
+}
+
+// static
+bool nsContentUtils::IsForbiddenRequestHeader(const nsACString& aHeader,
+                                              const nsACString& aValue) {
+  if (IsForbiddenSystemRequestHeader(aHeader)) {
+    return true;
+  }
+
+  if ((nsContentUtils::IsOverrideMethodHeader(aHeader) &&
+       nsContentUtils::ContainsForbiddenMethod(aValue))) {
+    return true;
+  }
+
+  if (StringBeginsWith(aHeader, "proxy-"_ns,
+                       nsCaseInsensitiveCStringComparator) ||
+      StringBeginsWith(aHeader, "sec-"_ns,
+                       nsCaseInsensitiveCStringComparator)) {
+    return true;
+  }
+
+  return false;
+}
+
+// static
+bool nsContentUtils::IsForbiddenSystemRequestHeader(const nsACString& aHeader) {
+  static const char* kInvalidHeaders[] = {"accept-charset",
+                                          "accept-encoding",
+                                          "access-control-request-headers",
+                                          "access-control-request-method",
+                                          "connection",
+                                          "content-length",
+                                          "cookie",
+                                          "cookie2",
+                                          "date",
+                                          "dnt",
+                                          "expect",
+                                          "host",
+                                          "keep-alive",
+                                          "origin",
+                                          "referer",
+                                          "set-cookie",
+                                          "te",
+                                          "trailer",
+                                          "transfer-encoding",
+                                          "upgrade",
+                                          "via"};
+  for (auto& kInvalidHeader : kInvalidHeaders) {
+    if (aHeader.LowerCaseEqualsASCII(kInvalidHeader)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// static
+bool nsContentUtils::IsForbiddenResponseHeader(const nsACString& aHeader) {
+  return (aHeader.LowerCaseEqualsASCII("set-cookie") ||
+          aHeader.LowerCaseEqualsASCII("set-cookie2"));
+}
+
+// static
+bool nsContentUtils::IsOverrideMethodHeader(const nsACString& headerName) {
+  return headerName.EqualsIgnoreCase("x-http-method-override") ||
+         headerName.EqualsIgnoreCase("x-http-method") ||
+         headerName.EqualsIgnoreCase("x-method-override");
+}
+
+// static
+bool nsContentUtils::ContainsForbiddenMethod(const nsACString& headerValue) {
+  bool hasInsecureMethod = false;
+  nsCCharSeparatedTokenizer tokenizer(headerValue, ',');
+
+  while (tokenizer.hasMoreTokens()) {
+    const nsDependentCSubstring& value = tokenizer.nextToken();
+
+    if (value.EqualsIgnoreCase("connect") || value.EqualsIgnoreCase("trace") ||
+        value.EqualsIgnoreCase("track")) {
+      hasInsecureMethod = true;
+      break;
+    }
+  }
+
+  return hasInsecureMethod;
+}
+
+// static
+bool nsContentUtils::IsCorsUnsafeRequestHeaderValue(
+    const nsACString& aHeaderValue) {
+  const char* cur = aHeaderValue.BeginReading();
+  const char* end = aHeaderValue.EndReading();
+
+  while (cur != end) {
+    // Implementation of
+    // https://fetch.spec.whatwg.org/#cors-unsafe-request-header-byte Is less
+    // than a space but not a horizontal tab
+    if ((*cur < ' ' && *cur != '\t') || *cur == '"' || *cur == '(' ||
+        *cur == ')' || *cur == ':' || *cur == '<' || *cur == '>' ||
+        *cur == '?' || *cur == '@' || *cur == '[' || *cur == '\\' ||
+        *cur == ']' || *cur == '{' || *cur == '}' ||
+        *cur == 0x7F) {  // 0x75 is DEL
+      return true;
+    }
+    cur++;
+  }
+  return false;
+}
+
+// static
+bool nsContentUtils::IsAllowedNonCorsAccept(const nsACString& aHeaderValue) {
+  if (IsCorsUnsafeRequestHeaderValue(aHeaderValue)) {
+    return false;
+  }
+  return true;
+}
+
+// static
+bool nsContentUtils::IsAllowedNonCorsContentType(
+    const nsACString& aHeaderValue) {
+  nsAutoCString contentType;
+  nsAutoCString unused;
+
+  if (IsCorsUnsafeRequestHeaderValue(aHeaderValue)) {
+    return false;
+  }
+
+  nsresult rv = NS_ParseRequestContentType(aHeaderValue, contentType, unused);
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  return contentType.LowerCaseEqualsLiteral("text/plain") ||
+         contentType.LowerCaseEqualsLiteral(
+             "application/x-www-form-urlencoded") ||
+         contentType.LowerCaseEqualsLiteral("multipart/form-data");
+}
+
+// static
+bool nsContentUtils::IsAllowedNonCorsLanguage(const nsACString& aHeaderValue) {
+  const char* cur = aHeaderValue.BeginReading();
+  const char* end = aHeaderValue.EndReading();
+
+  while (cur != end) {
+    if ((*cur >= '0' && *cur <= '9') || (*cur >= 'A' && *cur <= 'Z') ||
+        (*cur >= 'a' && *cur <= 'z') || *cur == ' ' || *cur == '*' ||
+        *cur == ',' || *cur == '-' || *cur == '.' || *cur == ';' ||
+        *cur == '=') {
+      cur++;
+      continue;
+    }
+    return false;
+  }
+  return true;
+}
+
+// static
+bool nsContentUtils::IsCORSSafelistedRequestHeader(const nsACString& aName,
+                                                   const nsACString& aValue) {
+  // see https://fetch.spec.whatwg.org/#cors-safelisted-request-header
+  if (aValue.Length() > 128) {
+    return false;
+  }
+  return (aName.LowerCaseEqualsLiteral("accept") &&
+          nsContentUtils::IsAllowedNonCorsAccept(aValue)) ||
+         (aName.LowerCaseEqualsLiteral("accept-language") &&
+          nsContentUtils::IsAllowedNonCorsLanguage(aValue)) ||
+         (aName.LowerCaseEqualsLiteral("content-language") &&
+          nsContentUtils::IsAllowedNonCorsLanguage(aValue)) ||
+         (aName.LowerCaseEqualsLiteral("content-type") &&
+          nsContentUtils::IsAllowedNonCorsContentType(aValue));
+}
+
+mozilla::LogModule* nsContentUtils::ResistFingerprintingLog() {
+  return gResistFingerprintingLog;
+}
+mozilla::LogModule* nsContentUtils::DOMDumpLog() { return sDOMDumpLog; }
+
+bool nsContentUtils::GetNodeTextContent(const nsINode* aNode, bool aDeep,
+                                        nsAString& aResult,
+                                        const fallible_t& aFallible) {
+  aResult.Truncate();
+  return AppendNodeTextContent(aNode, aDeep, aResult, aFallible);
+}
+
+void nsContentUtils::GetNodeTextContent(const nsINode* aNode, bool aDeep,
+                                        nsAString& aResult) {
+  if (!GetNodeTextContent(aNode, aDeep, aResult, fallible)) {
+    NS_ABORT_OOM(0);  // Unfortunately we don't know the allocation size
+  }
+}
+
+void nsContentUtils::DestroyMatchString(void* aData) {
+  if (aData) {
+    nsString* matchString = static_cast<nsString*>(aData);
+    delete matchString;
+  }
+}
+
+bool nsContentUtils::IsJavascriptMIMEType(const nsAString& aMIMEType) {
+  // Table ordered from most to least likely JS MIME types.
+  static const char* jsTypes[] = {"text/javascript",
+                                  "text/ecmascript",
+                                  "application/javascript",
+                                  "application/ecmascript",
+                                  "application/x-javascript",
+                                  "application/x-ecmascript",
+                                  "text/javascript1.0",
+                                  "text/javascript1.1",
+                                  "text/javascript1.2",
+                                  "text/javascript1.3",
+                                  "text/javascript1.4",
+                                  "text/javascript1.5",
+                                  "text/jscript",
+                                  "text/livescript",
+                                  "text/x-ecmascript",
+                                  "text/x-javascript",
+                                  nullptr};
+
+  for (uint32_t i = 0; jsTypes[i]; ++i) {
+    if (aMIMEType.LowerCaseEqualsASCII(jsTypes[i])) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool nsContentUtils::PrefetchPreloadEnabled(nsIDocShell* aDocShell) {
+  //
+  // SECURITY CHECK: disable prefetching and preloading from mailnews!
+  //
+  // walk up the docshell tree to see if any containing
+  // docshell are of type MAIL.
+  //
+
+  if (!aDocShell) {
+    return false;
+  }
+
+  nsCOMPtr<nsIDocShell> docshell = aDocShell;
+  nsCOMPtr<nsIDocShellTreeItem> parentItem;
+
+  do {
+    auto appType = docshell->GetAppType();
+    if (appType == nsIDocShell::APP_TYPE_MAIL) {
+      return false;  // do not prefetch, preload, preconnect from mailnews
+    }
+
+    docshell->GetInProcessParent(getter_AddRefs(parentItem));
+    if (parentItem) {
+      docshell = do_QueryInterface(parentItem);
+      if (!docshell) {
+        NS_ERROR("cannot get a docshell from a treeItem!");
+        return false;
+      }
+    }
+  } while (parentItem);
+
+  return true;
+}
+
+uint64_t nsContentUtils::GetInnerWindowID(nsIRequest* aRequest) {
+  // can't do anything if there's no nsIRequest!
+  if (!aRequest) {
+    return 0;
+  }
+
+  nsCOMPtr<nsILoadGroup> loadGroup;
+  nsresult rv = aRequest->GetLoadGroup(getter_AddRefs(loadGroup));
+
+  if (NS_FAILED(rv) || !loadGroup) {
+    return 0;
+  }
+
+  return GetInnerWindowID(loadGroup);
+}
+
+uint64_t nsContentUtils::GetInnerWindowID(nsILoadGroup* aLoadGroup) {
+  if (!aLoadGroup) {
+    return 0;
+  }
+
+  nsCOMPtr<nsIInterfaceRequestor> callbacks;
+  nsresult rv = aLoadGroup->GetNotificationCallbacks(getter_AddRefs(callbacks));
+  if (NS_FAILED(rv) || !callbacks) {
+    return 0;
+  }
+
+  nsCOMPtr<nsILoadContext> loadContext = do_GetInterface(callbacks);
+  if (!loadContext) {
+    return 0;
+  }
+
+  nsCOMPtr<mozIDOMWindowProxy> window;
+  rv = loadContext->GetAssociatedWindow(getter_AddRefs(window));
+  if (NS_FAILED(rv) || !window) {
+    return 0;
+  }
+
+  auto* pwindow = nsPIDOMWindowOuter::From(window);
+  if (!pwindow) {
+    return 0;
+  }
+
+  nsPIDOMWindowInner* inner = pwindow->GetCurrentInnerWindow();
+  return inner ? inner->WindowID() : 0;
+}
+
+// static
+void nsContentUtils::MaybeFixIPv6Host(nsACString& aHost) {
+  if (aHost.FindChar(':') != -1) {  // Escape IPv6 address
+    MOZ_ASSERT(!aHost.Length() ||
+               (aHost[0] != '[' && aHost[aHost.Length() - 1] != ']'));
+    aHost.Insert('[', 0);
+    aHost.Append(']');
+  }
+}
+
+nsresult nsContentUtils::GetHostOrIPv6WithBrackets(nsIURI* aURI,
+                                                   nsACString& aHost) {
+  aHost.Truncate();
+  nsresult rv = aURI->GetHost(aHost);
+  if (NS_FAILED(rv)) {  // Some URIs do not have a host
+    return rv;
+  }
+
+  MaybeFixIPv6Host(aHost);
+
+  return NS_OK;
+}
+
+nsresult nsContentUtils::GetHostOrIPv6WithBrackets(nsIURI* aURI,
+                                                   nsAString& aHost) {
+  nsAutoCString hostname;
+  nsresult rv = GetHostOrIPv6WithBrackets(aURI, hostname);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  CopyUTF8toUTF16(hostname, aHost);
+  return NS_OK;
+}
+
+nsresult nsContentUtils::GetHostOrIPv6WithBrackets(nsIPrincipal* aPrincipal,
+                                                   nsACString& aHost) {
+  nsresult rv = aPrincipal->GetAsciiHost(aHost);
+  if (NS_FAILED(rv)) {  // Some URIs do not have a host
+    return rv;
+  }
+
+  MaybeFixIPv6Host(aHost);
+  return NS_OK;
+}
+
+CallState nsContentUtils::CallOnAllRemoteChildren(
+    MessageBroadcaster* aManager,
+    const std::function<CallState(BrowserParent*)>& aCallback) {
+  uint32_t browserChildCount = aManager->ChildCount();
+  for (uint32_t j = 0; j < browserChildCount; ++j) {
+    RefPtr<MessageListenerManager> childMM = aManager->GetChildAt(j);
+    if (!childMM) {
+      continue;
+    }
+
+    RefPtr<MessageBroadcaster> nonLeafMM = MessageBroadcaster::From(childMM);
+    if (nonLeafMM) {
+      if (CallOnAllRemoteChildren(nonLeafMM, aCallback) == CallState::Stop) {
+        return CallState::Stop;
+      }
+      continue;
+    }
+
+    mozilla::dom::ipc::MessageManagerCallback* cb = childMM->GetCallback();
+    if (cb) {
+      nsFrameLoader* fl = static_cast<nsFrameLoader*>(cb);
+      BrowserParent* remote = BrowserParent::GetFrom(fl);
+      if (remote && aCallback) {
+        if (aCallback(remote) == CallState::Stop) {
+          return CallState::Stop;
+        }
+      }
+    }
+  }
+
+  return CallState::Continue;
+}
+
+void nsContentUtils::CallOnAllRemoteChildren(
+    nsPIDOMWindowOuter* aWindow,
+    const std::function<CallState(BrowserParent*)>& aCallback) {
+  nsGlobalWindowOuter* window = nsGlobalWindowOuter::Cast(aWindow);
+  if (window->IsChromeWindow()) {
+    RefPtr<MessageBroadcaster> windowMM = window->GetMessageManager();
+    if (windowMM) {
+      CallOnAllRemoteChildren(windowMM, aCallback);
+    }
+  }
+}
+
+bool nsContentUtils::IPCTransferableDataItemHasKnownFlavor(
+    const IPCTransferableDataItem& aItem) {
+  // Unknown types are converted to kCustomTypesMime.
+  if (aItem.flavor().EqualsASCII(kCustomTypesMime)) {
+    return true;
+  }
+
+  for (const char* format : DataTransfer::kKnownFormats) {
+    if (aItem.flavor().EqualsASCII(format)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+nsresult nsContentUtils::IPCTransferableDataToTransferable(
+    const IPCTransferableData& aTransferableData, bool aAddDataFlavor,
+    nsITransferable* aTransferable, const bool aFilterUnknownFlavors) {
+  nsresult rv;
+  const nsTArray<IPCTransferableDataItem>& items = aTransferableData.items();
+  for (const auto& item : items) {
+    if (aFilterUnknownFlavors && !IPCTransferableDataItemHasKnownFlavor(item)) {
+      NS_WARNING(
+          "Ignoring unknown flavor in "
+          "nsContentUtils::IPCTransferableDataToTransferable");
+      continue;
+    }
+
+    if (aAddDataFlavor) {
+      aTransferable->AddDataFlavor(item.flavor().get());
+    }
+
+    nsCOMPtr<nsISupports> transferData;
+    switch (item.data().type()) {
+      case IPCTransferableDataType::TIPCTransferableDataString: {
+        const auto& data = item.data().get_IPCTransferableDataString();
+        nsCOMPtr<nsISupportsString> dataWrapper =
+            do_CreateInstance(NS_SUPPORTS_STRING_CONTRACTID, &rv);
+        NS_ENSURE_SUCCESS(rv, rv);
+        rv = dataWrapper->SetData(nsDependentSubstring(
+            reinterpret_cast<const char16_t*>(data.data().Data()),
+            data.data().Size() / sizeof(char16_t)));
+        NS_ENSURE_SUCCESS(rv, rv);
+        transferData = dataWrapper;
+        break;
+      }
+      case IPCTransferableDataType::TIPCTransferableDataCString: {
+        const auto& data = item.data().get_IPCTransferableDataCString();
+        nsCOMPtr<nsISupportsCString> dataWrapper =
+            do_CreateInstance(NS_SUPPORTS_CSTRING_CONTRACTID, &rv);
+        NS_ENSURE_SUCCESS(rv, rv);
+        rv = dataWrapper->SetData(nsDependentCSubstring(
+            reinterpret_cast<const char*>(data.data().Data()),
+            data.data().Size()));
+        NS_ENSURE_SUCCESS(rv, rv);
+        transferData = dataWrapper;
+        break;
+      }
+      case IPCTransferableDataType::TIPCTransferableDataInputStream: {
+        const auto& data = item.data().get_IPCTransferableDataInputStream();
+        nsCOMPtr<nsIInputStream> stream;
+        rv = NS_NewByteInputStream(getter_AddRefs(stream),
+                                   AsChars(data.data().AsSpan()),
+                                   NS_ASSIGNMENT_COPY);
+        NS_ENSURE_SUCCESS(rv, rv);
+        transferData = stream.forget();
+        break;
+      }
+      case IPCTransferableDataType::TIPCTransferableDataImageContainer: {
+        const auto& data = item.data().get_IPCTransferableDataImageContainer();
+        nsCOMPtr<imgIContainer> container;
+        rv = DeserializeTransferableDataImageContainer(
+            data, getter_AddRefs(container));
+        NS_ENSURE_SUCCESS(rv, rv);
+        transferData = container;
+        break;
+      }
+      case IPCTransferableDataType::TIPCTransferableDataBlob: {
+        const auto& data = item.data().get_IPCTransferableDataBlob();
+        transferData = IPCBlobUtils::Deserialize(data.blob());
+        break;
+      }
+      case IPCTransferableDataType::T__None:
+        MOZ_ASSERT_UNREACHABLE();
+        return NS_ERROR_FAILURE;
+    }
+
+    rv = aTransferable->SetTransferData(item.flavor().get(), transferData);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+  return NS_OK;
+}
+
+nsresult nsContentUtils::IPCTransferableDataToTransferable(
+    const IPCTransferableData& aTransferableData, const bool& aIsPrivateData,
+    nsIPrincipal* aRequestingPrincipal,
+    const nsContentPolicyType& aContentPolicyType, bool aAddDataFlavor,
+    nsITransferable* aTransferable, const bool aFilterUnknownFlavors) {
+  // Note that we need to set privacy status of transferable before adding any
+  // data into it.
+  aTransferable->SetIsPrivateData(aIsPrivateData);
+
+  nsresult rv = IPCTransferableDataToTransferable(
+      aTransferableData, aAddDataFlavor, aTransferable, aFilterUnknownFlavors);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  aTransferable->SetRequestingPrincipal(aRequestingPrincipal);
+  aTransferable->SetContentPolicyType(aContentPolicyType);
+  return NS_OK;
+}
+
+nsresult nsContentUtils::IPCTransferableToTransferable(
+    const IPCTransferable& aIPCTransferable, bool aAddDataFlavor,
+    nsITransferable* aTransferable, const bool aFilterUnknownFlavors) {
+  nsresult rv = IPCTransferableDataToTransferable(
+      aIPCTransferable.data(), aIPCTransferable.isPrivateData(),
+      aIPCTransferable.requestingPrincipal(),
+      aIPCTransferable.contentPolicyType(), aAddDataFlavor, aTransferable,
+      aFilterUnknownFlavors);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (aIPCTransferable.cookieJarSettings().isSome()) {
+    nsCOMPtr<nsICookieJarSettings> cookieJarSettings;
+    net::CookieJarSettings::Deserialize(
+        aIPCTransferable.cookieJarSettings().ref(),
+        getter_AddRefs(cookieJarSettings));
+    aTransferable->SetCookieJarSettings(cookieJarSettings);
+  }
+  aTransferable->SetReferrerInfo(aIPCTransferable.referrerInfo());
+  return NS_OK;
+}
+
+nsresult nsContentUtils::IPCTransferableDataItemToVariant(
+    const IPCTransferableDataItem& aItem, nsIWritableVariant* aVariant) {
+  MOZ_ASSERT(aVariant);
+
+  switch (aItem.data().type()) {
+    case IPCTransferableDataType::TIPCTransferableDataString: {
+      const auto& data = aItem.data().get_IPCTransferableDataString();
+      return aVariant->SetAsAString(nsDependentSubstring(
+          reinterpret_cast<const char16_t*>(data.data().Data()),
+          data.data().Size() / sizeof(char16_t)));
+    }
+    case IPCTransferableDataType::TIPCTransferableDataCString: {
+      const auto& data = aItem.data().get_IPCTransferableDataCString();
+      return aVariant->SetAsACString(nsDependentCSubstring(
+          reinterpret_cast<const char*>(data.data().Data()),
+          data.data().Size()));
+    }
+    case IPCTransferableDataType::TIPCTransferableDataInputStream: {
+      const auto& data = aItem.data().get_IPCTransferableDataInputStream();
+      nsCOMPtr<nsIInputStream> stream;
+      nsresult rv = NS_NewByteInputStream(getter_AddRefs(stream),
+                                          AsChars(data.data().AsSpan()),
+                                          NS_ASSIGNMENT_COPY);
+      NS_ENSURE_SUCCESS(rv, rv);
+      return aVariant->SetAsISupports(stream);
+    }
+    case IPCTransferableDataType::TIPCTransferableDataImageContainer: {
+      const auto& data = aItem.data().get_IPCTransferableDataImageContainer();
+      nsCOMPtr<imgIContainer> container;
+      nsresult rv = DeserializeTransferableDataImageContainer(
+          data, getter_AddRefs(container));
+      NS_ENSURE_SUCCESS(rv, rv);
+      return aVariant->SetAsISupports(container);
+    }
+    case IPCTransferableDataType::TIPCTransferableDataBlob: {
+      const auto& data = aItem.data().get_IPCTransferableDataBlob();
+      RefPtr<BlobImpl> blobImpl = IPCBlobUtils::Deserialize(data.blob());
+      return aVariant->SetAsISupports(blobImpl);
+    }
+    case IPCTransferableDataType::T__None:
+      break;
+  }
+
+  MOZ_ASSERT_UNREACHABLE();
+  return NS_ERROR_UNEXPECTED;
+}
+
+void nsContentUtils::TransferablesToIPCTransferableDatas(
+    nsIArray* aTransferables, nsTArray<IPCTransferableData>& aIPC,
+    bool aInSyncMessage, mozilla::dom::ContentParent* aParent) {
+  aIPC.Clear();
+  if (aTransferables) {
+    uint32_t transferableCount = 0;
+    aTransferables->GetLength(&transferableCount);
+    for (uint32_t i = 0; i < transferableCount; ++i) {
+      IPCTransferableData* dt = aIPC.AppendElement();
+      nsCOMPtr<nsITransferable> transferable =
+          do_QueryElementAt(aTransferables, i);
+      TransferableToIPCTransferableData(transferable, dt, aInSyncMessage,
+                                        aParent);
+    }
+  }
+}
+
+nsresult nsContentUtils::CalculateBufferSizeForImage(
+    const uint32_t& aStride, const IntSize& aImageSize,
+    const SurfaceFormat& aFormat, size_t* aMaxBufferSize,
+    size_t* aUsedBufferSize) {
+  CheckedInt32 requiredBytes =
+      CheckedInt32(aStride) * CheckedInt32(aImageSize.height);
+
+  CheckedInt32 usedBytes =
+      requiredBytes - aStride +
+      (CheckedInt32(aImageSize.width) * BytesPerPixel(aFormat));
+  if (!usedBytes.isValid()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  MOZ_ASSERT(requiredBytes.isValid(), "usedBytes valid but not required?");
+  *aMaxBufferSize = requiredBytes.value();
+  *aUsedBufferSize = usedBytes.value();
+  return NS_OK;
+}
+
+static already_AddRefed<DataSourceSurface> BigBufferToDataSurface(
+    BigBuffer& aData, uint32_t aStride, const IntSize& aImageSize,
+    SurfaceFormat aFormat) {
+  if (!aData.Size() || !aImageSize.width || !aImageSize.height) {
+    return nullptr;
+  }
+
+  // Validate shared memory buffer size
+  size_t imageBufLen = 0;
+  size_t maxBufLen = 0;
+  if (NS_FAILED(nsContentUtils::CalculateBufferSizeForImage(
+          aStride, aImageSize, aFormat, &maxBufLen, &imageBufLen))) {
+    return nullptr;
+  }
+  if (imageBufLen > aData.Size()) {
+    return nullptr;
+  }
+  return CreateDataSourceSurfaceFromData(aImageSize, aFormat, aData.Data(),
+                                         aStride);
+}
+
+nsresult nsContentUtils::DeserializeTransferableDataImageContainer(
+    const IPCTransferableDataImageContainer& aData,
+    imgIContainer** aContainer) {
+  const IntSize size(aData.width(), aData.height());
+  size_t maxBufferSize = 0;
+  size_t usedBufferSize = 0;
+  nsresult rv = CalculateBufferSizeForImage(
+      aData.stride(), size, aData.format(), &maxBufferSize, &usedBufferSize);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (usedBufferSize > aData.data().Size()) {
+    return NS_ERROR_FAILURE;
+  }
+  RefPtr<DataSourceSurface> surface =
+      CreateDataSourceSurfaceFromData(size, aData.format(), aData.data().Data(),
+                                      static_cast<int32_t>(aData.stride()));
+  if (!surface) {
+    return NS_ERROR_FAILURE;
+  }
+  RefPtr<gfxDrawable> drawable = new gfxSurfaceDrawable(surface, size);
+  nsCOMPtr<imgIContainer> imageContainer =
+      image::ImageOps::CreateFromDrawable(drawable);
+  imageContainer.forget(aContainer);
+
+  return NS_OK;
+}
+
+bool nsContentUtils::IsFlavorImage(const nsACString& aFlavor) {
+  return aFlavor.EqualsLiteral(kNativeImageMime) ||
+         aFlavor.EqualsLiteral(kJPEGImageMime) ||
+         aFlavor.EqualsLiteral(kJPGImageMime) ||
+         aFlavor.EqualsLiteral(kPNGImageMime) ||
+         aFlavor.EqualsLiteral(kGIFImageMime);
+}
+
+// FIXME: This can probably be removed once bug 1783240 lands, as `nsString`
+// will be implicitly serialized in shmem when sent over IPDL directly.
+static IPCTransferableDataString AsIPCTransferableDataString(
+    Span<const char16_t> aInput) {
+  return IPCTransferableDataString{BigBuffer(AsBytes(aInput))};
+}
+
+// FIXME: This can probably be removed once bug 1783240 lands, as `nsCString`
+// will be implicitly serialized in shmem when sent over IPDL directly.
+static IPCTransferableDataCString AsIPCTransferableDataCString(
+    Span<const char> aInput) {
+  return IPCTransferableDataCString{BigBuffer(AsBytes(aInput))};
+}
+
+void nsContentUtils::TransferableToIPCTransferableData(
+    nsITransferable* aTransferable, IPCTransferableData* aTransferableData,
+    bool aInSyncMessage, mozilla::dom::ContentParent* aParent) {
+  MOZ_ASSERT_IF(XRE_IsParentProcess(), aParent);
+
+  if (aTransferable) {
+    nsTArray<nsCString> flavorList;
+    aTransferable->FlavorsTransferableCanExport(flavorList);
+
+    for (uint32_t j = 0; j < flavorList.Length(); ++j) {
+      nsCString& flavorStr = flavorList[j];
+      if (!flavorStr.Length()) {
+        continue;
+      }
+
+      nsCOMPtr<nsISupports> data;
+      nsresult rv =
+          aTransferable->GetTransferData(flavorStr.get(), getter_AddRefs(data));
+
+      if (NS_FAILED(rv) || !data) {
+        if (aInSyncMessage) {
+          // Can't do anything.
+          // FIXME: This shouldn't be the case anymore!
+          continue;
+        }
+
+        // This is a hack to support kFilePromiseMime.
+        // On Windows there just needs to be an entry for it,
+        // and for OSX we need to create
+        // nsContentAreaDragDropDataProvider as nsIFlavorDataProvider.
+        if (flavorStr.EqualsLiteral(kFilePromiseMime)) {
+          IPCTransferableDataItem* item =
+              aTransferableData->items().AppendElement();
+          item->flavor() = flavorStr;
+          item->data() =
+              AsIPCTransferableDataString(NS_ConvertUTF8toUTF16(flavorStr));
+          continue;
+        }
+
+        // Empty element, transfer only the flavor
+        IPCTransferableDataItem* item =
+            aTransferableData->items().AppendElement();
+        item->flavor() = flavorStr;
+        item->data() = AsIPCTransferableDataString(EmptyString());
+        continue;
+      }
+
+      // We need to handle nsIInputStream before nsISupportsCString, otherwise
+      // nsStringInputStream would be converted into a wrong type.
+      if (nsCOMPtr<nsIInputStream> stream = do_QueryInterface(data)) {
+        IPCTransferableDataItem* item =
+            aTransferableData->items().AppendElement();
+        item->flavor() = flavorStr;
+        nsCString imageData;
+        DebugOnly<nsresult> rv =
+            NS_ConsumeStream(stream, UINT32_MAX, imageData);
+        MOZ_ASSERT(
+            rv != NS_BASE_STREAM_WOULD_BLOCK,
+            "cannot use async input streams in nsITransferable right now");
+        // FIXME: This can probably be simplified once bug 1783240 lands, as
+        // `nsCString` will be implicitly serialized in shmem when sent over
+        // IPDL directly.
+        item->data() =
+            IPCTransferableDataInputStream(BigBuffer(AsBytes(Span(imageData))));
+        continue;
+      }
+
+      if (nsCOMPtr<nsISupportsString> text = do_QueryInterface(data)) {
+        nsAutoString dataAsString;
+        MOZ_ALWAYS_SUCCEEDS(text->GetData(dataAsString));
+
+        IPCTransferableDataItem* item =
+            aTransferableData->items().AppendElement();
+        item->flavor() = flavorStr;
+        item->data() = AsIPCTransferableDataString(dataAsString);
+        continue;
+      }
+
+      if (nsCOMPtr<nsISupportsCString> ctext = do_QueryInterface(data)) {
+        nsAutoCString dataAsString;
+        MOZ_ALWAYS_SUCCEEDS(ctext->GetData(dataAsString));
+
+        IPCTransferableDataItem* item =
+            aTransferableData->items().AppendElement();
+        item->flavor() = flavorStr;
+        item->data() = AsIPCTransferableDataCString(dataAsString);
+        continue;
+      }
+
+      if (nsCOMPtr<imgIContainer> image = do_QueryInterface(data)) {
+        // Images to be placed on the clipboard are imgIContainers.
+        RefPtr<mozilla::gfx::SourceSurface> surface = image->GetFrame(
+            imgIContainer::FRAME_CURRENT,
+            imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
+        if (!surface) {
+          continue;
+        }
+        RefPtr<mozilla::gfx::DataSourceSurface> dataSurface =
+            surface->GetDataSurface();
+        if (!dataSurface) {
+          continue;
+        }
+        size_t length;
+        int32_t stride;
+        Maybe<BigBuffer> surfaceData =
+            GetSurfaceData(*dataSurface, &length, &stride);
+
+        if (surfaceData.isNothing()) {
+          continue;
+        }
+
+        IPCTransferableDataItem* item =
+            aTransferableData->items().AppendElement();
+        item->flavor() = flavorStr;
+
+        mozilla::gfx::IntSize size = dataSurface->GetSize();
+        item->data() = IPCTransferableDataImageContainer(
+            std::move(*surfaceData), size.width, size.height, stride,
+            dataSurface->GetFormat());
+        continue;
+      }
+
+      // Otherwise, handle this as a file.
+      nsCOMPtr<BlobImpl> blobImpl;
+      if (nsCOMPtr<nsIFile> file = do_QueryInterface(data)) {
+        if (aParent) {
+          bool isDir = false;
+          if (NS_SUCCEEDED(file->IsDirectory(&isDir)) && isDir) {
+            nsAutoString path;
+            if (NS_WARN_IF(NS_FAILED(file->GetPath(path)))) {
+              continue;
+            }
+
+            RefPtr<FileSystemSecurity> fss = FileSystemSecurity::GetOrCreate();
+            fss->GrantAccessToContentProcess(aParent->ChildID(), path);
+          }
+        }
+
+        blobImpl = new FileBlobImpl(file);
+
+        IgnoredErrorResult rv;
+
+        // Ensure that file data is cached no that the content process
+        // has this data available to it when passed over:
+        blobImpl->GetSize(rv);
+        if (NS_WARN_IF(rv.Failed())) {
+          continue;
+        }
+
+        blobImpl->GetLastModified(rv);
+        if (NS_WARN_IF(rv.Failed())) {
+          continue;
+        }
+      } else {
+        if (aInSyncMessage) {
+          // Can't do anything.
+          // FIXME: This shouldn't be the case anymore!
+          continue;
+        }
+
+        blobImpl = do_QueryInterface(data);
+      }
+
+      if (blobImpl) {
+        // If we failed to create the blob actor, then this blob probably
+        // can't get the file size for the underlying file, ignore it for
+        // now. TODO pass this through anyway.
+        IPCBlob ipcBlob;
+        nsresult rv = IPCBlobUtils::Serialize(blobImpl, ipcBlob);
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+          continue;
+        }
+
+        IPCTransferableDataItem* item =
+            aTransferableData->items().AppendElement();
+        item->flavor() = flavorStr;
+        item->data() = IPCTransferableDataBlob(ipcBlob);
+      }
+    }
+  }
+}
+
+void nsContentUtils::TransferableToIPCTransferable(
+    nsITransferable* aTransferable, IPCTransferable* aIPCTransferable,
+    bool aInSyncMessage, mozilla::dom::ContentParent* aParent) {
+  IPCTransferableData ipcTransferableData;
+  TransferableToIPCTransferableData(aTransferable, &ipcTransferableData,
+                                    aInSyncMessage, aParent);
+
+  Maybe<net::CookieJarSettingsArgs> cookieJarSettingsArgs;
+  if (nsCOMPtr<nsICookieJarSettings> cookieJarSettings =
+          aTransferable->GetCookieJarSettings()) {
+    net::CookieJarSettingsArgs args;
+    net::CookieJarSettings::Cast(cookieJarSettings)->Serialize(args);
+    cookieJarSettingsArgs = Some(std::move(args));
+  }
+
+  aIPCTransferable->data() = std::move(ipcTransferableData);
+  aIPCTransferable->isPrivateData() = aTransferable->GetIsPrivateData();
+  aIPCTransferable->requestingPrincipal() =
+      aTransferable->GetRequestingPrincipal();
+  aIPCTransferable->cookieJarSettings() = std::move(cookieJarSettingsArgs);
+  aIPCTransferable->contentPolicyType() = aTransferable->GetContentPolicyType();
+  aIPCTransferable->referrerInfo() = aTransferable->GetReferrerInfo();
+}
+
+Maybe<BigBuffer> nsContentUtils::GetSurfaceData(DataSourceSurface& aSurface,
+                                                size_t* aLength,
+                                                int32_t* aStride) {
+  mozilla::gfx::DataSourceSurface::MappedSurface map;
+  if (!aSurface.Map(mozilla::gfx::DataSourceSurface::MapType::READ, &map)) {
+    return Nothing();
+  }
+
+  size_t bufLen = 0;
+  size_t maxBufLen = 0;
+  nsresult rv = nsContentUtils::CalculateBufferSizeForImage(
+      map.mStride, aSurface.GetSize(), aSurface.GetFormat(), &maxBufLen,
+      &bufLen);
+  if (NS_FAILED(rv)) {
+    aSurface.Unmap();
+    return Nothing();
+  }
+
+  BigBuffer surfaceData(maxBufLen);
+  memcpy(surfaceData.Data(), map.mData, bufLen);
+  memset(surfaceData.Data() + bufLen, 0, maxBufLen - bufLen);
+
+  *aLength = maxBufLen;
+  *aStride = map.mStride;
+
+  aSurface.Unmap();
+  return Some(std::move(surfaceData));
+}
+
+Maybe<IPCImage> nsContentUtils::SurfaceToIPCImage(DataSourceSurface& aSurface) {
+  size_t len = 0;
+  int32_t stride = 0;
+  auto mem = GetSurfaceData(aSurface, &len, &stride);
+  if (!mem) {
+    return Nothing();
+  }
+  return Some(IPCImage{std::move(*mem), uint32_t(stride), aSurface.GetFormat(),
+                       ImageIntSize::FromUnknownSize(aSurface.GetSize())});
+}
+
+already_AddRefed<DataSourceSurface> nsContentUtils::IPCImageToSurface(
+    IPCImage&& aImage) {
+  return BigBufferToDataSurface(aImage.data(), aImage.stride(),
+                                aImage.size().ToUnknownSize(), aImage.format());
+}
+
+Modifiers nsContentUtils::GetWidgetModifiers(int32_t aModifiers) {
+  Modifiers result = 0;
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_SHIFT) {
+    result |= mozilla::MODIFIER_SHIFT;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_CONTROL) {
+    result |= mozilla::MODIFIER_CONTROL;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_ALT) {
+    result |= mozilla::MODIFIER_ALT;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_META) {
+    result |= mozilla::MODIFIER_META;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_ALTGRAPH) {
+    result |= mozilla::MODIFIER_ALTGRAPH;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_CAPSLOCK) {
+    result |= mozilla::MODIFIER_CAPSLOCK;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_FN) {
+    result |= mozilla::MODIFIER_FN;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_FNLOCK) {
+    result |= mozilla::MODIFIER_FNLOCK;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_NUMLOCK) {
+    result |= mozilla::MODIFIER_NUMLOCK;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_SCROLLLOCK) {
+    result |= mozilla::MODIFIER_SCROLLLOCK;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_SYMBOL) {
+    result |= mozilla::MODIFIER_SYMBOL;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_SYMBOLLOCK) {
+    result |= mozilla::MODIFIER_SYMBOLLOCK;
+  }
+  if (aModifiers & nsIDOMWindowUtils::MODIFIER_OS) {
+    result |= mozilla::MODIFIER_OS;
+  }
+  return result;
+}
+
+nsIWidget* nsContentUtils::GetWidget(PresShell* aPresShell, nsPoint* aOffset) {
+  if (!aPresShell) {
+    return nullptr;
+  }
+  nsIFrame* frame = aPresShell->GetRootFrame();
+  if (!frame) {
+    return nullptr;
+  }
+  return frame->GetView()->GetNearestWidget(aOffset);
+}
+
+int16_t nsContentUtils::GetButtonsFlagForButton(int32_t aButton) {
+  switch (aButton) {
+    case -1:
+      return MouseButtonsFlag::eNoButtons;
+    case MouseButton::ePrimary:
+      return MouseButtonsFlag::ePrimaryFlag;
+    case MouseButton::eMiddle:
+      return MouseButtonsFlag::eMiddleFlag;
+    case MouseButton::eSecondary:
+      return MouseButtonsFlag::eSecondaryFlag;
+    case 3:
+      return MouseButtonsFlag::e4thFlag;
+    case 4:
+      return MouseButtonsFlag::e5thFlag;
+    case MouseButton::eEraser:
+      return MouseButtonsFlag::eEraserFlag;
+    default:
+      NS_ERROR("Button not known.");
+      return 0;
+  }
+}
+
+LayoutDeviceIntPoint nsContentUtils::ToWidgetPoint(
+    const CSSPoint& aPoint, const nsPoint& aOffset,
+    nsPresContext* aPresContext) {
+  nsPoint layoutRelative = CSSPoint::ToAppUnits(aPoint) + aOffset;
+  nsPoint visualRelative =
+      ViewportUtils::LayoutToVisual(layoutRelative, aPresContext->PresShell());
+  return LayoutDeviceIntPoint::FromAppUnitsRounded(
+      visualRelative, aPresContext->AppUnitsPerDevPixel());
+}
+
+nsView* nsContentUtils::GetViewToDispatchEvent(nsPresContext* aPresContext,
+                                               PresShell** aPresShell) {
+  if (!aPresContext || !aPresShell) {
+    return nullptr;
+  }
+  RefPtr<PresShell> presShell = aPresContext->PresShell();
+  if (NS_WARN_IF(!presShell)) {
+    *aPresShell = nullptr;
+    return nullptr;
+  }
+  nsViewManager* viewManager = presShell->GetViewManager();
+  if (!viewManager) {
+    presShell.forget(aPresShell);  // XXX Is this intentional?
+    return nullptr;
+  }
+  presShell.forget(aPresShell);
+  return viewManager->GetRootView();
+}
+
+nsresult nsContentUtils::SendMouseEvent(
+    mozilla::PresShell* aPresShell, const nsAString& aType, float aX, float aY,
+    int32_t aButton, int32_t aButtons, int32_t aClickCount, int32_t aModifiers,
+    bool aIgnoreRootScrollFrame, float aPressure,
+    unsigned short aInputSourceArg, uint32_t aIdentifier, bool aToWindow,
+    PreventDefaultResult* aPreventDefault, bool aIsDOMEventSynthesized,
+    bool aIsWidgetEventSynthesized) {
+  nsPoint offset;
+  nsCOMPtr<nsIWidget> widget = GetWidget(aPresShell, &offset);
+  if (!widget) return NS_ERROR_FAILURE;
+
+  EventMessage msg;
+  Maybe<WidgetMouseEvent::ExitFrom> exitFrom;
+  bool contextMenuKey = false;
+  if (aType.EqualsLiteral("mousedown")) {
+    msg = eMouseDown;
+  } else if (aType.EqualsLiteral("mouseup")) {
+    msg = eMouseUp;
+  } else if (aType.EqualsLiteral("mousemove")) {
+    msg = eMouseMove;
+  } else if (aType.EqualsLiteral("mouseover")) {
+    msg = eMouseEnterIntoWidget;
+  } else if (aType.EqualsLiteral("mouseout")) {
+    msg = eMouseExitFromWidget;
+    exitFrom = Some(WidgetMouseEvent::ePlatformChild);
+  } else if (aType.EqualsLiteral("mousecancel")) {
+    msg = eMouseExitFromWidget;
+    exitFrom = Some(XRE_IsParentProcess() ? WidgetMouseEvent::ePlatformTopLevel
+                                          : WidgetMouseEvent::ePuppet);
+  } else if (aType.EqualsLiteral("mouselongtap")) {
+    msg = eMouseLongTap;
+  } else if (aType.EqualsLiteral("contextmenu")) {
+    msg = eContextMenu;
+    contextMenuKey = (aButton == 0);
+  } else if (aType.EqualsLiteral("MozMouseHittest")) {
+    msg = eMouseHitTest;
+  } else if (aType.EqualsLiteral("MozMouseExploreByTouch")) {
+    msg = eMouseExploreByTouch;
+  } else {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (aInputSourceArg == MouseEvent_Binding::MOZ_SOURCE_UNKNOWN) {
+    aInputSourceArg = MouseEvent_Binding::MOZ_SOURCE_MOUSE;
+  }
+
+  WidgetMouseEvent event(true, msg, widget,
+                         aIsWidgetEventSynthesized
+                             ? WidgetMouseEvent::eSynthesized
+                             : WidgetMouseEvent::eReal,
+                         contextMenuKey ? WidgetMouseEvent::eContextMenuKey
+                                        : WidgetMouseEvent::eNormal);
+  event.pointerId = aIdentifier;
+  event.mModifiers = GetWidgetModifiers(aModifiers);
+  event.mButton = aButton;
+  event.mButtons = aButtons != nsIDOMWindowUtils::MOUSE_BUTTONS_NOT_SPECIFIED
+                       ? aButtons
+                   : msg == eMouseUp ? 0
+                                     : GetButtonsFlagForButton(aButton);
+  event.mPressure = aPressure;
+  event.mInputSource = aInputSourceArg;
+  event.mClickCount = aClickCount;
+  event.mFlags.mIsSynthesizedForTests = aIsDOMEventSynthesized;
+  event.mExitFrom = exitFrom;
+
+  nsPresContext* presContext = aPresShell->GetPresContext();
+  if (!presContext) return NS_ERROR_FAILURE;
+
+  event.mRefPoint = ToWidgetPoint(CSSPoint(aX, aY), offset, presContext);
+  event.mIgnoreRootScrollFrame = aIgnoreRootScrollFrame;
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  if (aToWindow) {
+    RefPtr<PresShell> presShell;
+    nsView* view =
+        GetViewToDispatchEvent(presContext, getter_AddRefs(presShell));
+    if (!presShell || !view) {
+      return NS_ERROR_FAILURE;
+    }
+    return presShell->HandleEvent(view->GetFrame(), &event, false, &status);
+  }
+  if (StaticPrefs::test_events_async_enabled()) {
+    status = widget->DispatchInputEvent(&event).mContentStatus;
+  } else {
+    nsresult rv = widget->DispatchEvent(&event, status);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+  if (aPreventDefault) {
+    if (status == nsEventStatus_eConsumeNoDefault) {
+      if (event.mFlags.mDefaultPreventedByContent) {
+        *aPreventDefault = PreventDefaultResult::ByContent;
+      } else {
+        *aPreventDefault = PreventDefaultResult::ByChrome;
+      }
+    } else {
+      *aPreventDefault = PreventDefaultResult::No;
+    }
+  }
+
+  return NS_OK;
+}
+
+/* static */
+void nsContentUtils::FirePageHideEventForFrameLoaderSwap(
+    nsIDocShellTreeItem* aItem, EventTarget* aChromeEventHandler,
+    bool aOnlySystemGroup) {
+  MOZ_DIAGNOSTIC_ASSERT(aItem);
+  MOZ_DIAGNOSTIC_ASSERT(aChromeEventHandler);
+
+  RefPtr<Document> doc = aItem->GetDocument();
+  NS_ASSERTION(doc, "What happened here?");
+  doc->OnPageHide(true, aChromeEventHandler, aOnlySystemGroup);
+
+  int32_t childCount = 0;
+  aItem->GetInProcessChildCount(&childCount);
+  AutoTArray<nsCOMPtr<nsIDocShellTreeItem>, 8> kids;
+  kids.AppendElements(childCount);
+  for (int32_t i = 0; i < childCount; ++i) {
+    aItem->GetInProcessChildAt(i, getter_AddRefs(kids[i]));
+  }
+
+  for (uint32_t i = 0; i < kids.Length(); ++i) {
+    if (kids[i]) {
+      FirePageHideEventForFrameLoaderSwap(kids[i], aChromeEventHandler,
+                                          aOnlySystemGroup);
+    }
+  }
+}
+
+// The pageshow event is fired for a given document only if IsShowing() returns
+// the same thing as aFireIfShowing.  This gives us a way to fire pageshow only
+// on documents that are still loading or only on documents that are already
+// loaded.
+/* static */
+void nsContentUtils::FirePageShowEventForFrameLoaderSwap(
+    nsIDocShellTreeItem* aItem, EventTarget* aChromeEventHandler,
+    bool aFireIfShowing, bool aOnlySystemGroup) {
+  int32_t childCount = 0;
+  aItem->GetInProcessChildCount(&childCount);
+  AutoTArray<nsCOMPtr<nsIDocShellTreeItem>, 8> kids;
+  kids.AppendElements(childCount);
+  for (int32_t i = 0; i < childCount; ++i) {
+    aItem->GetInProcessChildAt(i, getter_AddRefs(kids[i]));
+  }
+
+  for (uint32_t i = 0; i < kids.Length(); ++i) {
+    if (kids[i]) {
+      FirePageShowEventForFrameLoaderSwap(kids[i], aChromeEventHandler,
+                                          aFireIfShowing, aOnlySystemGroup);
+    }
+  }
+
+  RefPtr<Document> doc = aItem->GetDocument();
+  if (doc && doc->IsShowing() == aFireIfShowing) {
+    doc->OnPageShow(true, aChromeEventHandler, aOnlySystemGroup);
+  }
+}
+
+/* static */
+already_AddRefed<nsPIWindowRoot> nsContentUtils::GetWindowRoot(Document* aDoc) {
+  if (aDoc) {
+    if (nsPIDOMWindowOuter* win = aDoc->GetWindow()) {
+      return win->GetTopWindowRoot();
+    }
+  }
+  return nullptr;
+}
+
+/* static */
+bool nsContentUtils::LinkContextIsURI(const nsAString& aAnchor,
+                                      nsIURI* aDocURI) {
+  if (aAnchor.IsEmpty()) {
+    // anchor parameter not present or empty -> same document reference
+    return true;
+  }
+
+  // the document URI might contain a fragment identifier ("#...')
+  // we want to ignore that because it's invisible to the server
+  // and just affects the local interpretation in the recipient
+  nsCOMPtr<nsIURI> contextUri;
+  nsresult rv = NS_GetURIWithoutRef(aDocURI, getter_AddRefs(contextUri));
+
+  if (NS_FAILED(rv)) {
+    // copying failed
+    return false;
+  }
+
+  // resolve anchor against context
+  nsCOMPtr<nsIURI> resolvedUri;
+  rv = NS_NewURI(getter_AddRefs(resolvedUri), aAnchor, nullptr, contextUri);
+
+  if (NS_FAILED(rv)) {
+    // resolving failed
+    return false;
+  }
+
+  bool same;
+  rv = contextUri->Equals(resolvedUri, &same);
+  if (NS_FAILED(rv)) {
+    // comparison failed
+    return false;
+  }
+
+  return same;
+}
+
+/* static */
+bool nsContentUtils::IsPreloadType(nsContentPolicyType aType) {
+  return (aType == nsIContentPolicy::TYPE_INTERNAL_SCRIPT_PRELOAD ||
+          aType == nsIContentPolicy::TYPE_INTERNAL_MODULE_PRELOAD ||
+          aType == nsIContentPolicy::TYPE_INTERNAL_IMAGE_PRELOAD ||
+          aType == nsIContentPolicy::TYPE_INTERNAL_STYLESHEET_PRELOAD ||
+          aType == nsIContentPolicy::TYPE_INTERNAL_FONT_PRELOAD ||
+          aType == nsIContentPolicy::TYPE_INTERNAL_FETCH_PRELOAD);
+}
+
+// static
+ReferrerPolicy nsContentUtils::GetReferrerPolicyFromChannel(
+    nsIChannel* aChannel) {
+  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aChannel);
+  if (!httpChannel) {
+    return ReferrerPolicy::_empty;
+  }
+
+  nsresult rv;
+  nsAutoCString headerValue;
+  rv = httpChannel->GetResponseHeader("referrer-policy"_ns, headerValue);
+  if (NS_FAILED(rv) || headerValue.IsEmpty()) {
+    return ReferrerPolicy::_empty;
+  }
+
+  return ReferrerInfo::ReferrerPolicyFromHeaderString(
+      NS_ConvertUTF8toUTF16(headerValue));
+}
+
+// static
+bool nsContentUtils::IsNonSubresourceRequest(nsIChannel* aChannel) {
+  nsLoadFlags loadFlags = 0;
+  aChannel->GetLoadFlags(&loadFlags);
+  if (loadFlags & nsIChannel::LOAD_DOCUMENT_URI) {
+    return true;
+  }
+
+  nsCOMPtr<nsILoadInfo> loadInfo = aChannel->LoadInfo();
+  nsContentPolicyType type = loadInfo->InternalContentPolicyType();
+  return IsNonSubresourceInternalPolicyType(type);
+}
+
+// static
+bool nsContentUtils::IsNonSubresourceInternalPolicyType(
+    nsContentPolicyType aType) {
+  return aType == nsIContentPolicy::TYPE_DOCUMENT ||
+         aType == nsIContentPolicy::TYPE_INTERNAL_IFRAME ||
+         aType == nsIContentPolicy::TYPE_INTERNAL_FRAME ||
+         aType == nsIContentPolicy::TYPE_INTERNAL_WORKER ||
+         aType == nsIContentPolicy::TYPE_INTERNAL_SHARED_WORKER;
+}
+
+// static public
+bool nsContentUtils::IsThirdPartyTrackingResourceWindow(
+    nsPIDOMWindowInner* aWindow) {
+  MOZ_ASSERT(aWindow);
+
+  Document* document = aWindow->GetExtantDoc();
+  if (!document) {
+    return false;
+  }
+
+  nsCOMPtr<nsIClassifiedChannel> classifiedChannel =
+      do_QueryInterface(document->GetChannel());
+  if (!classifiedChannel) {
+    return false;
+  }
+
+  return classifiedChannel->IsThirdPartyTrackingResource();
+}
+
+// static public
+bool nsContentUtils::IsFirstPartyTrackingResourceWindow(
+    nsPIDOMWindowInner* aWindow) {
+  MOZ_ASSERT(aWindow);
+
+  Document* document = aWindow->GetExtantDoc();
+  if (!document) {
+    return false;
+  }
+
+  nsCOMPtr<nsIClassifiedChannel> classifiedChannel =
+      do_QueryInterface(document->GetChannel());
+  if (!classifiedChannel) {
+    return false;
+  }
+
+  uint32_t classificationFlags =
+      classifiedChannel->GetFirstPartyClassificationFlags();
+
+  return mozilla::net::UrlClassifierCommon::IsTrackingClassificationFlag(
+      classificationFlags, NS_UsePrivateBrowsing(document->GetChannel()));
+}
+
+namespace {
+
+// We put StringBuilder in the anonymous namespace to prevent anything outside
+// this file from accidentally being linked against it.
+class BulkAppender {
+  using size_type = typename nsAString::size_type;
+
+ public:
+  explicit BulkAppender(BulkWriteHandle<char16_t>&& aHandle)
+      : mHandle(std::move(aHandle)), mPosition(0) {}
+  ~BulkAppender() = default;
+
+  template <int N>
+  void AppendLiteral(const char16_t (&aStr)[N]) {
+    size_t len = N - 1;
+    MOZ_ASSERT(mPosition + len <= mHandle.Length());
+    memcpy(mHandle.Elements() + mPosition, aStr, len * sizeof(char16_t));
+    mPosition += len;
+  }
+
+  void Append(Span<const char16_t> aStr) {
+    size_t len = aStr.Length();
+    MOZ_ASSERT(mPosition + len <= mHandle.Length());
+    // Both mHandle.Elements() and aStr.Elements() are guaranteed
+    // to be non-null (by the string implementation and by Span,
+    // respectively), so not checking the pointers for null before
+    // memcpy does not lead to UB even if len was zero.
+    memcpy(mHandle.Elements() + mPosition, aStr.Elements(),
+           len * sizeof(char16_t));
+    mPosition += len;
+  }
+
+  void Append(Span<const char> aStr) {
+    size_t len = aStr.Length();
+    MOZ_ASSERT(mPosition + len <= mHandle.Length());
+    ConvertLatin1toUtf16(aStr, mHandle.AsSpan().From(mPosition));
+    mPosition += len;
+  }
+
+  void Finish() { mHandle.Finish(mPosition, false); }
+
+ private:
+  BulkWriteHandle<char16_t> mHandle;
+  size_type mPosition;
+};
+
+class StringBuilder {
+ private:
+  class Unit {
+   public:
+    Unit() : mAtom(nullptr) { MOZ_COUNT_CTOR(StringBuilder::Unit); }
+    ~Unit() {
+      if (mType == Type::String || mType == Type::StringWithEncode) {
+        mString.~nsString();
+      }
+      MOZ_COUNT_DTOR(StringBuilder::Unit);
+    }
+
+    enum class Type : uint8_t {
+      Unknown,
+      Atom,
+      String,
+      StringWithEncode,
+      Literal,
+      TextFragment,
+      TextFragmentWithEncode,
+    };
+
+    union {
+      nsAtom* mAtom;
+      const char16_t* mLiteral;
+      nsString mString;
+      const nsTextFragment* mTextFragment;
+    };
+    uint32_t mLength = 0;
+    Type mType = Type::Unknown;
+  };
+
+  static_assert(sizeof(void*) != 8 || sizeof(Unit) <= 3 * sizeof(void*),
+                "Unit should remain small");
+
+ public:
+  // Try to keep the size of StringBuilder close to a jemalloc bucket size (the
+  // 16kb one in this case).
+  static constexpr uint32_t TARGET_SIZE = 16 * 1024;
+
+  // The number of units we need to remove from the inline buffer so that the
+  // rest of the builder members fit. A more precise approach would be to
+  // calculate that extra size and use (TARGET_SIZE - OTHER_SIZE) / sizeof(Unit)
+  // or so, but this is simpler.
+  static constexpr uint32_t PADDING_UNITS = sizeof(void*) == 8 ? 1 : 2;
+
+  static constexpr uint32_t STRING_BUFFER_UNITS =
+      TARGET_SIZE / sizeof(Unit) - PADDING_UNITS;
+
+  StringBuilder() : mLast(this), mLength(0) { MOZ_COUNT_CTOR(StringBuilder); }
+
+  MOZ_COUNTED_DTOR(StringBuilder)
+
+  void Append(nsAtom* aAtom) {
+    Unit* u = AddUnit();
+    u->mAtom = aAtom;
+    u->mType = Unit::Type::Atom;
+    uint32_t len = aAtom->GetLength();
+    u->mLength = len;
+    mLength += len;
+  }
+
+  template <int N>
+  void Append(const char16_t (&aLiteral)[N]) {
+    Unit* u = AddUnit();
+    u->mLiteral = aLiteral;
+    u->mType = Unit::Type::Literal;
+    uint32_t len = N - 1;
+    u->mLength = len;
+    mLength += len;
+  }
+
+  void Append(nsString&& aString) {
+    Unit* u = AddUnit();
+    uint32_t len = aString.Length();
+    new (&u->mString) nsString(std::move(aString));
+    u->mType = Unit::Type::String;
+    u->mLength = len;
+    mLength += len;
+  }
+
+  void AppendWithAttrEncode(nsString&& aString, uint32_t aLen) {
+    Unit* u = AddUnit();
+    new (&u->mString) nsString(std::move(aString));
+    u->mType = Unit::Type::StringWithEncode;
+    u->mLength = aLen;
+    mLength += aLen;
+  }
+
+  void Append(const nsTextFragment* aTextFragment) {
+    Unit* u = AddUnit();
+    u->mTextFragment = aTextFragment;
+    u->mType = Unit::Type::TextFragment;
+    uint32_t len = aTextFragment->GetLength();
+    u->mLength = len;
+    mLength += len;
+  }
+
+  void AppendWithEncode(const nsTextFragment* aTextFragment, uint32_t aLen) {
+    Unit* u = AddUnit();
+    u->mTextFragment = aTextFragment;
+    u->mType = Unit::Type::TextFragmentWithEncode;
+    u->mLength = aLen;
+    mLength += aLen;
+  }
+
+  bool ToString(nsAString& aOut) {
+    if (!mLength.isValid()) {
+      return false;
+    }
+    auto appenderOrErr = aOut.BulkWrite(mLength.value(), 0, true);
+    if (appenderOrErr.isErr()) {
+      return false;
+    }
+
+    BulkAppender appender{appenderOrErr.unwrap()};
+
+    for (StringBuilder* current = this; current;
+         current = current->mNext.get()) {
+      uint32_t len = current->mUnits.Length();
+      for (uint32_t i = 0; i < len; ++i) {
+        Unit& u = current->mUnits[i];
+        switch (u.mType) {
+          case Unit::Type::Atom:
+            appender.Append(*(u.mAtom));
+            break;
+          case Unit::Type::String:
+            appender.Append(u.mString);
+            break;
+          case Unit::Type::StringWithEncode:
+            EncodeAttrString(u.mString, appender);
+            break;
+          case Unit::Type::Literal:
+            appender.Append(Span(u.mLiteral, u.mLength));
+            break;
+          case Unit::Type::TextFragment:
+            if (u.mTextFragment->Is2b()) {
+              appender.Append(
+                  Span(u.mTextFragment->Get2b(), u.mTextFragment->GetLength()));
+            } else {
+              appender.Append(
+                  Span(u.mTextFragment->Get1b(), u.mTextFragment->GetLength()));
+            }
+            break;
+          case Unit::Type::TextFragmentWithEncode:
+            if (u.mTextFragment->Is2b()) {
+              EncodeTextFragment(
+                  Span(u.mTextFragment->Get2b(), u.mTextFragment->GetLength()),
+                  appender);
+            } else {
+              EncodeTextFragment(
+                  Span(u.mTextFragment->Get1b(), u.mTextFragment->GetLength()),
+                  appender);
+            }
+            break;
+          default:
+            MOZ_CRASH("Unknown unit type?");
+        }
+      }
+    }
+    appender.Finish();
+    return true;
+  }
+
+ private:
+  Unit* AddUnit() {
+    if (mLast->mUnits.Length() == STRING_BUFFER_UNITS) {
+      new StringBuilder(this);
+    }
+    return mLast->mUnits.AppendElement();
+  }
+
+  explicit StringBuilder(StringBuilder* aFirst) : mLast(nullptr), mLength(0) {
+    MOZ_COUNT_CTOR(StringBuilder);
+    aFirst->mLast->mNext = WrapUnique(this);
+    aFirst->mLast = this;
+  }
+
+  void EncodeAttrString(Span<const char16_t> aStr, BulkAppender& aAppender) {
+    size_t flushedUntil = 0;
+    size_t currentPosition = 0;
+    for (char16_t c : aStr) {
+      switch (c) {
+        case '"':
+          aAppender.Append(aStr.FromTo(flushedUntil, currentPosition));
+          aAppender.AppendLiteral(u"&quot;");
+          flushedUntil = currentPosition + 1;
+          break;
+        case '&':
+          aAppender.Append(aStr.FromTo(flushedUntil, currentPosition));
+          aAppender.AppendLiteral(u"&amp;");
+          flushedUntil = currentPosition + 1;
+          break;
+        case 0x00A0:
+          aAppender.Append(aStr.FromTo(flushedUntil, currentPosition));
+          aAppender.AppendLiteral(u"&nbsp;");
+          flushedUntil = currentPosition + 1;
+          break;
+        default:
+          break;
+      }
+      currentPosition++;
+    }
+    if (currentPosition > flushedUntil) {
+      aAppender.Append(aStr.FromTo(flushedUntil, currentPosition));
+    }
+  }
+
+  template <class T>
+  void EncodeTextFragment(Span<const T> aStr, BulkAppender& aAppender) {
+    size_t flushedUntil = 0;
+    size_t currentPosition = 0;
+    for (T c : aStr) {
+      switch (c) {
+        case '<':
+          aAppender.Append(aStr.FromTo(flushedUntil, currentPosition));
+          aAppender.AppendLiteral(u"&lt;");
+          flushedUntil = currentPosition + 1;
+          break;
+        case '>':
+          aAppender.Append(aStr.FromTo(flushedUntil, currentPosition));
+          aAppender.AppendLiteral(u"&gt;");
+          flushedUntil = currentPosition + 1;
+          break;
+        case '&':
+          aAppender.Append(aStr.FromTo(flushedUntil, currentPosition));
+          aAppender.AppendLiteral(u"&amp;");
+          flushedUntil = currentPosition + 1;
+          break;
+        case T(0xA0):
+          aAppender.Append(aStr.FromTo(flushedUntil, currentPosition));
+          aAppender.AppendLiteral(u"&nbsp;");
+          flushedUntil = currentPosition + 1;
+          break;
+        default:
+          break;
+      }
+      currentPosition++;
+    }
+    if (currentPosition > flushedUntil) {
+      aAppender.Append(aStr.FromTo(flushedUntil, currentPosition));
+    }
+  }
+
+  AutoTArray<Unit, STRING_BUFFER_UNITS> mUnits;
+  UniquePtr<StringBuilder> mNext;
+  StringBuilder* mLast;
+  // mLength is used only in the first StringBuilder object in the linked list.
+  CheckedInt<uint32_t> mLength;
+};
+
+static_assert(sizeof(StringBuilder) <= StringBuilder::TARGET_SIZE,
+              "StringBuilder should fit in the target bucket");
+
+}  // namespace
+
+static void AppendEncodedCharacters(const nsTextFragment* aText,
+                                    StringBuilder& aBuilder) {
+  uint32_t extraSpaceNeeded = 0;
+  uint32_t len = aText->GetLength();
+  if (aText->Is2b()) {
+    const char16_t* data = aText->Get2b();
+    for (uint32_t i = 0; i < len; ++i) {
+      const char16_t c = data[i];
+      switch (c) {
+        case '<':
+          extraSpaceNeeded += ArrayLength("&lt;") - 2;
+          break;
+        case '>':
+          extraSpaceNeeded += ArrayLength("&gt;") - 2;
+          break;
+        case '&':
+          extraSpaceNeeded += ArrayLength("&amp;") - 2;
+          break;
+        case 0x00A0:
+          extraSpaceNeeded += ArrayLength("&nbsp;") - 2;
+          break;
+        default:
+          break;
+      }
+    }
+  } else {
+    const char* data = aText->Get1b();
+    for (uint32_t i = 0; i < len; ++i) {
+      const unsigned char c = data[i];
+      switch (c) {
+        case '<':
+          extraSpaceNeeded += ArrayLength("&lt;") - 2;
+          break;
+        case '>':
+          extraSpaceNeeded += ArrayLength("&gt;") - 2;
+          break;
+        case '&':
+          extraSpaceNeeded += ArrayLength("&amp;") - 2;
+          break;
+        case 0x00A0:
+          extraSpaceNeeded += ArrayLength("&nbsp;") - 2;
+          break;
+        default:
+          break;
+      }
+    }
+  }
+
+  if (extraSpaceNeeded) {
+    aBuilder.AppendWithEncode(aText, len + extraSpaceNeeded);
+  } else {
+    aBuilder.Append(aText);
+  }
+}
+
+static uint32_t ExtraSpaceNeededForAttrEncoding(const nsAString& aValue) {
+  const char16_t* c = aValue.BeginReading();
+  const char16_t* end = aValue.EndReading();
+
+  uint32_t extraSpaceNeeded = 0;
+  while (c < end) {
+    switch (*c) {
+      case '"':
+        extraSpaceNeeded += ArrayLength("&quot;") - 2;
+        break;
+      case '&':
+        extraSpaceNeeded += ArrayLength("&amp;") - 2;
+        break;
+      case 0x00A0:
+        extraSpaceNeeded += ArrayLength("&nbsp;") - 2;
+        break;
+      default:
+        break;
+    }
+    ++c;
+  }
+
+  return extraSpaceNeeded;
+}
+
+static void AppendEncodedAttributeValue(const nsAttrValue& aValue,
+                                        StringBuilder& aBuilder) {
+  if (nsAtom* atom = aValue.GetStoredAtom()) {
+    nsDependentAtomString atomStr(atom);
+    uint32_t space = ExtraSpaceNeededForAttrEncoding(atomStr);
+    if (!space) {
+      aBuilder.Append(atom);
+    } else {
+      aBuilder.AppendWithAttrEncode(nsString(atomStr),
+                                    atomStr.Length() + space);
+    }
+    return;
+  }
+  // NOTE(emilio): In most cases this will just be a reference to the stored
+  // nsStringBuffer.
+  nsString str;
+  aValue.ToString(str);
+  uint32_t space = ExtraSpaceNeededForAttrEncoding(str);
+  if (space) {
+    aBuilder.AppendWithAttrEncode(std::move(str), str.Length() + space);
+  } else {
+    aBuilder.Append(std::move(str));
+  }
+}
+
+static void StartElement(Element* aElement, StringBuilder& aBuilder) {
+  nsAtom* localName = aElement->NodeInfo()->NameAtom();
+  const int32_t tagNS = aElement->GetNameSpaceID();
+
+  aBuilder.Append(u"<");
+  if (tagNS == kNameSpaceID_XHTML || tagNS == kNameSpaceID_SVG ||
+      tagNS == kNameSpaceID_MathML) {
+    aBuilder.Append(localName);
+  } else {
+    aBuilder.Append(nsString(aElement->NodeName()));
+  }
+
+  if (CustomElementData* ceData = aElement->GetCustomElementData()) {
+    nsAtom* isAttr = ceData->GetIs(aElement);
+    if (isAttr && !aElement->HasAttr(nsGkAtoms::is)) {
+      aBuilder.Append(uR"( is=")");
+      aBuilder.Append(isAttr);
+      aBuilder.Append(uR"(")");
+    }
+  }
+
+  uint32_t i = 0;
+  while (BorrowedAttrInfo info = aElement->GetAttrInfoAt(i++)) {
+    const nsAttrName* name = info.mName;
+
+    int32_t attNs = name->NamespaceID();
+    nsAtom* attName = name->LocalName();
+
+    // Filter out any attribute starting with [-|_]moz
+    // FIXME(emilio): Do we still need this?
+    nsDependentAtomString attrNameStr(attName);
+    if (StringBeginsWith(attrNameStr, u"_moz"_ns) ||
+        StringBeginsWith(attrNameStr, u"-moz"_ns)) {
+      continue;
+    }
+
+    aBuilder.Append(u" ");
+
+    if (MOZ_LIKELY(attNs == kNameSpaceID_None) ||
+        (attNs == kNameSpaceID_XMLNS && attName == nsGkAtoms::xmlns)) {
+      // Nothing else required
+    } else if (attNs == kNameSpaceID_XML) {
+      aBuilder.Append(u"xml:");
+    } else if (attNs == kNameSpaceID_XMLNS) {
+      aBuilder.Append(u"xmlns:");
+    } else if (attNs == kNameSpaceID_XLink) {
+      aBuilder.Append(u"xlink:");
+    } else if (nsAtom* prefix = name->GetPrefix()) {
+      aBuilder.Append(prefix);
+      aBuilder.Append(u":");
+    }
+
+    aBuilder.Append(attName);
+    aBuilder.Append(uR"(=")");
+    AppendEncodedAttributeValue(*info.mValue, aBuilder);
+    aBuilder.Append(uR"(")");
+  }
+
+  aBuilder.Append(u">");
+
+  /*
+  // Per HTML spec we should append one \n if the first child of
+  // pre/textarea/listing is a textnode and starts with a \n.
+  // But because browsers haven't traditionally had that behavior,
+  // we're not changing our behavior either - yet.
+  if (aContent->IsHTMLElement()) {
+    if (localName == nsGkAtoms::pre || localName == nsGkAtoms::textarea ||
+        localName == nsGkAtoms::listing) {
+      nsIContent* fc = aContent->GetFirstChild();
+      if (fc &&
+          (fc->NodeType() == nsINode::TEXT_NODE ||
+           fc->NodeType() == nsINode::CDATA_SECTION_NODE)) {
+        const nsTextFragment* text = fc->GetText();
+        if (text && text->GetLength() && text->CharAt(0) == char16_t('\n')) {
+          aBuilder.Append("\n");
+        }
+      }
+    }
+  }*/
+}
+
+static inline bool ShouldEscape(nsIContent* aParent) {
+  if (!aParent || !aParent->IsHTMLElement()) {
+    return true;
+  }
+
+  static const nsAtom* nonEscapingElements[] = {
+      nsGkAtoms::style,     nsGkAtoms::script,  nsGkAtoms::xmp,
+      nsGkAtoms::iframe,    nsGkAtoms::noembed, nsGkAtoms::noframes,
+      nsGkAtoms::plaintext, nsGkAtoms::noscript};
+  static mozilla::BitBloomFilter<12, nsAtom> sFilter;
+  static bool sInitialized = false;
+  if (!sInitialized) {
+    sInitialized = true;
+    for (auto& nonEscapingElement : nonEscapingElements) {
+      sFilter.add(nonEscapingElement);
+    }
+  }
+
+  nsAtom* tag = aParent->NodeInfo()->NameAtom();
+  if (sFilter.mightContain(tag)) {
+    for (auto& nonEscapingElement : nonEscapingElements) {
+      if (tag == nonEscapingElement) {
+        if (MOZ_UNLIKELY(tag == nsGkAtoms::noscript) &&
+            MOZ_UNLIKELY(!aParent->OwnerDoc()->IsScriptEnabled())) {
+          return true;
+        }
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+static inline bool IsVoidTag(Element* aElement) {
+  if (!aElement->IsHTMLElement()) {
+    return false;
+  }
+  return FragmentOrElement::IsHTMLVoid(aElement->NodeInfo()->NameAtom());
+}
+
+bool nsContentUtils::SerializeNodeToMarkup(nsINode* aRoot,
+                                           bool aDescendantsOnly,
+                                           nsAString& aOut) {
+  // If you pass in a DOCUMENT_NODE, you must pass aDescendentsOnly as true
+  MOZ_ASSERT(aDescendantsOnly || aRoot->NodeType() != nsINode::DOCUMENT_NODE);
+
+  nsINode* current =
+      aDescendantsOnly ? aRoot->GetFirstChildOfTemplateOrNode() : aRoot;
+
+  if (!current) {
+    return true;
+  }
+
+  StringBuilder builder;
+  nsIContent* next;
+  while (true) {
+    bool isVoid = false;
+    switch (current->NodeType()) {
+      case nsINode::ELEMENT_NODE: {
+        Element* elem = current->AsElement();
+        StartElement(elem, builder);
+        isVoid = IsVoidTag(elem);
+        if (!isVoid && (next = current->GetFirstChildOfTemplateOrNode())) {
+          current = next;
+          continue;
+        }
+        break;
+      }
+
+      case nsINode::TEXT_NODE:
+      case nsINode::CDATA_SECTION_NODE: {
+        const nsTextFragment* text = &current->AsText()->TextFragment();
+        nsIContent* parent = current->GetParent();
+        if (ShouldEscape(parent)) {
+          AppendEncodedCharacters(text, builder);
+        } else {
+          builder.Append(text);
+        }
+        break;
+      }
+
+      case nsINode::COMMENT_NODE: {
+        builder.Append(u"<!--");
+        builder.Append(static_cast<nsIContent*>(current)->GetText());
+        builder.Append(u"-->");
+        break;
+      }
+
+      case nsINode::DOCUMENT_TYPE_NODE: {
+        builder.Append(u"<!DOCTYPE ");
+        builder.Append(nsString(current->NodeName()));
+        builder.Append(u">");
+        break;
+      }
+
+      case nsINode::PROCESSING_INSTRUCTION_NODE: {
+        builder.Append(u"<?");
+        builder.Append(nsString(current->NodeName()));
+        builder.Append(u" ");
+        builder.Append(static_cast<nsIContent*>(current)->GetText());
+        builder.Append(u">");
+        break;
+      }
+    }
+
+    while (true) {
+      if (!isVoid && current->NodeType() == nsINode::ELEMENT_NODE) {
+        builder.Append(u"</");
+        nsIContent* elem = static_cast<nsIContent*>(current);
+        if (elem->IsHTMLElement() || elem->IsSVGElement() ||
+            elem->IsMathMLElement()) {
+          builder.Append(elem->NodeInfo()->NameAtom());
+        } else {
+          builder.Append(nsString(current->NodeName()));
+        }
+        builder.Append(u">");
+      }
+      isVoid = false;
+
+      if (current == aRoot) {
+        return builder.ToString(aOut);
+      }
+
+      if ((next = current->GetNextSibling())) {
+        current = next;
+        break;
+      }
+
+      current = current->GetParentNode();
+
+      // Handle template element. If the parent is a template's content,
+      // then adjust the parent to be the template element.
+      if (current != aRoot &&
+          current->NodeType() == nsINode::DOCUMENT_FRAGMENT_NODE) {
+        DocumentFragment* frag = static_cast<DocumentFragment*>(current);
+        nsIContent* fragHost = frag->GetHost();
+        if (fragHost && fragHost->IsTemplateElement()) {
+          current = fragHost;
+        }
+      }
+
+      if (aDescendantsOnly && current == aRoot) {
+        return builder.ToString(aOut);
+      }
+    }
+  }
+}
+
+bool nsContentUtils::IsSpecificAboutPage(JSObject* aGlobal, const char* aUri) {
+  // aUri must start with about: or this isn't the right function to be using.
+  MOZ_ASSERT(strncmp(aUri, "about:", 6) == 0);
+
+  // Make sure the global is a window
+  MOZ_DIAGNOSTIC_ASSERT(JS_IsGlobalObject(aGlobal));
+  nsGlobalWindowInner* win = xpc::WindowOrNull(aGlobal);
+  if (!win) {
+    return false;
+  }
+
+  nsCOMPtr<nsIPrincipal> principal = win->GetPrincipal();
+  NS_ENSURE_TRUE(principal, false);
+
+  // First check the scheme to avoid getting long specs in the common case.
+  if (!principal->SchemeIs("about")) {
+    return false;
+  }
+
+  nsAutoCString spec;
+  principal->GetAsciiSpec(spec);
+
+  return spec.EqualsASCII(aUri);
+}
+
+/* static */
+void nsContentUtils::SetScrollbarsVisibility(nsIDocShell* aDocShell,
+                                             bool aVisible) {
+  if (!aDocShell) {
+    return;
+  }
+  auto pref = aVisible ? ScrollbarPreference::Auto : ScrollbarPreference::Never;
+  nsDocShell::Cast(aDocShell)->SetScrollbarPreference(pref);
+}
+
+/* static */
+nsIDocShell* nsContentUtils::GetDocShellForEventTarget(EventTarget* aTarget) {
+  if (!aTarget) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsPIDOMWindowInner> innerWindow;
+  if (nsCOMPtr<nsINode> node = nsINode::FromEventTarget(aTarget)) {
+    bool ignore;
+    innerWindow =
+        do_QueryInterface(node->OwnerDoc()->GetScriptHandlingObject(ignore));
+  } else if ((innerWindow = nsPIDOMWindowInner::FromEventTarget(aTarget))) {
+    // Nothing else to do
+  } else {
+    nsCOMPtr<DOMEventTargetHelper> helper = do_QueryInterface(aTarget);
+    if (helper) {
+      innerWindow = helper->GetOwner();
+    }
+  }
+
+  if (innerWindow) {
+    return innerWindow->GetDocShell();
+  }
+
+  return nullptr;
+}
+
+/*
+ * Note: this function only relates to figuring out HTTPS state, which is an
+ * input to the Secure Context algorithm.  We are not actually implementing any
+ * part of the Secure Context algorithm itself here.
+ *
+ * This is a bit of a hack.  Ideally we'd propagate HTTPS state through
+ * nsIChannel as described in the Fetch and HTML specs, but making channels
+ * know about whether they should inherit HTTPS state, propagating information
+ * about who the channel's "client" is, exposing GetHttpsState API on channels
+ * and modifying the various cache implementations to store and retrieve HTTPS
+ * state involves a huge amount of code (see bug 1220687).  We avoid that for
+ * now using this function.
+ *
+ * This function takes advantage of the observation that we can return true if
+ * nsIContentSecurityManager::IsOriginPotentiallyTrustworthy returns true for
+ * the document's origin (e.g. the origin has a scheme of 'https' or host
+ * 'localhost' etc.).  Since we generally propagate a creator document's origin
+ * onto data:, blob:, etc. documents, this works for them too.
+ *
+ * The scenario where this observation breaks down is sandboxing without the
+ * 'allow-same-origin' flag, since in this case a document is given a unique
+ * origin (IsOriginPotentiallyTrustworthy would return false).  We handle that
+ * by using the origin that the document would have had had it not been
+ * sandboxed.
+ *
+ * DEFICIENCIES: Note that this function uses nsIScriptSecurityManager's
+ * getChannelResultPrincipalIfNotSandboxed, and that method's ignoring of
+ * sandboxing is limited to the immediate sandbox.  In the case that aDocument
+ * should inherit its origin (e.g. data: URI) but its parent has ended up
+ * with a unique origin due to sandboxing further up the parent chain we may
+ * end up returning false when we would ideally return true (since we will
+ * examine the parent's origin for 'https' and not finding it.)  This means
+ * that we may restrict the privileges of some pages unnecessarily in this
+ * edge case.
+ */
+/* static */
+bool nsContentUtils::HttpsStateIsModern(Document* aDocument) {
+  if (!aDocument) {
+    return false;
+  }
+
+  nsCOMPtr<nsIPrincipal> principal = aDocument->NodePrincipal();
+
+  if (principal->IsSystemPrincipal()) {
+    return true;
+  }
+
+  // If aDocument is sandboxed, try and get the principal that it would have
+  // been given had it not been sandboxed:
+  if (principal->GetIsNullPrincipal() &&
+      (aDocument->GetSandboxFlags() & SANDBOXED_ORIGIN)) {
+    nsIChannel* channel = aDocument->GetChannel();
+    if (channel) {
+      nsCOMPtr<nsIScriptSecurityManager> ssm =
+          nsContentUtils::GetSecurityManager();
+      nsresult rv = ssm->GetChannelResultPrincipalIfNotSandboxed(
+          channel, getter_AddRefs(principal));
+      if (NS_FAILED(rv)) {
+        return false;
+      }
+      if (principal->IsSystemPrincipal()) {
+        // If a document with the system principal is sandboxing a subdocument
+        // that would normally inherit the embedding element's principal (e.g.
+        // a srcdoc document) then the embedding document does not trust the
+        // content that is written to the embedded document.  Unlike when the
+        // embedding document is https, in this case we have no indication as
+        // to whether the embedded document's contents are delivered securely
+        // or not, and the sandboxing would possibly indicate that they were
+        // not.  To play it safe we return false here.  (See bug 1162772
+        // comment 73-80.)
+        return false;
+      }
+    }
+  }
+
+  if (principal->GetIsNullPrincipal()) {
+    return false;
+  }
+
+  MOZ_ASSERT(principal->GetIsContentPrincipal());
+
+  return principal->GetIsOriginPotentiallyTrustworthy();
+}
+
+/* static */
+bool nsContentUtils::ComputeIsSecureContext(nsIChannel* aChannel) {
+  MOZ_ASSERT(aChannel);
+
+  nsCOMPtr<nsIScriptSecurityManager> ssm = nsContentUtils::GetSecurityManager();
+  nsCOMPtr<nsIPrincipal> principal;
+  nsresult rv = ssm->GetChannelResultPrincipalIfNotSandboxed(
+      aChannel, getter_AddRefs(principal));
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  const RefPtr<nsILoadInfo> loadInfo = aChannel->LoadInfo();
+
+  if (principal->IsSystemPrincipal()) {
+    // If the load would've been sandboxed, treat this load as an untrusted
+    // load, as system code considers sandboxed resources insecure.
+    return !loadInfo->GetLoadingSandboxed();
+  }
+
+  if (principal->GetIsNullPrincipal()) {
+    return false;
+  }
+
+  if (const RefPtr<WindowContext> windowContext =
+          WindowContext::GetById(loadInfo->GetInnerWindowID())) {
+    if (!windowContext->GetIsSecureContext()) {
+      return false;
+    }
+  }
+
+  return principal->GetIsOriginPotentiallyTrustworthy();
+}
+
+/* static */
+void nsContentUtils::TryToUpgradeElement(Element* aElement) {
+  NodeInfo* nodeInfo = aElement->NodeInfo();
+  RefPtr<nsAtom> typeAtom =
+      aElement->GetCustomElementData()->GetCustomElementType();
+
+  MOZ_ASSERT(nodeInfo->NameAtom()->Equals(nodeInfo->LocalName()));
+  CustomElementDefinition* definition =
+      nsContentUtils::LookupCustomElementDefinition(
+          nodeInfo->GetDocument(), nodeInfo->NameAtom(),
+          nodeInfo->NamespaceID(), typeAtom);
+  if (definition) {
+    nsContentUtils::EnqueueUpgradeReaction(aElement, definition);
+  } else {
+    // Add an unresolved custom element that is a candidate for upgrade when a
+    // custom element is connected to the document.
+    nsContentUtils::RegisterUnresolvedElement(aElement, typeAtom);
+  }
+}
+
+MOZ_CAN_RUN_SCRIPT
+static void DoCustomElementCreate(Element** aElement, JSContext* aCx,
+                                  Document* aDoc, NodeInfo* aNodeInfo,
+                                  CustomElementConstructor* aConstructor,
+                                  ErrorResult& aRv) {
+  JS::Rooted<JS::Value> constructResult(aCx);
+  aConstructor->Construct(&constructResult, aRv, "Custom Element Create",
+                          CallbackFunction::eRethrowExceptions);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  RefPtr<Element> element;
+  // constructResult is an ObjectValue because construction with a callback
+  // always forms the return value from a JSObject.
+  UNWRAP_OBJECT(Element, &constructResult, element);
+  if (aNodeInfo->NamespaceEquals(kNameSpaceID_XHTML)) {
+    if (!element || !element->IsHTMLElement()) {
+      aRv.ThrowTypeError<MSG_DOES_NOT_IMPLEMENT_INTERFACE>("\"this\"",
+                                                           "HTMLElement");
+      return;
+    }
+  } else {
+    if (!element || !element->IsXULElement()) {
+      aRv.ThrowTypeError<MSG_DOES_NOT_IMPLEMENT_INTERFACE>("\"this\"",
+                                                           "XULElement");
+      return;
+    }
+  }
+
+  nsAtom* localName = aNodeInfo->NameAtom();
+
+  if (aDoc != element->OwnerDoc() || element->GetParentNode() ||
+      element->HasChildren() || element->GetAttrCount() ||
+      element->NodeInfo()->NameAtom() != localName) {
+    aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
+    return;
+  }
+
+  element.forget(aElement);
+}
+
+/* static */
+nsresult nsContentUtils::NewXULOrHTMLElement(
+    Element** aResult, mozilla::dom::NodeInfo* aNodeInfo,
+    FromParser aFromParser, nsAtom* aIsAtom,
+    mozilla::dom::CustomElementDefinition* aDefinition) {
+  RefPtr<mozilla::dom::NodeInfo> nodeInfo = aNodeInfo;
+  MOZ_ASSERT(nodeInfo->NamespaceEquals(kNameSpaceID_XHTML) ||
+                 nodeInfo->NamespaceEquals(kNameSpaceID_XUL),
+             "Can only create XUL or XHTML elements.");
+
+  nsAtom* name = nodeInfo->NameAtom();
+  int32_t tag = eHTMLTag_unknown;
+  bool isCustomElementName = false;
+  if (nodeInfo->NamespaceEquals(kNameSpaceID_XHTML)) {
+    tag = nsHTMLTags::CaseSensitiveAtomTagToId(name);
+    isCustomElementName =
+        (tag == eHTMLTag_userdefined &&
+         nsContentUtils::IsCustomElementName(name, kNameSpaceID_XHTML));
+  } else {  // kNameSpaceID_XUL
+    if (aIsAtom) {
+      // Make sure the customized built-in element to be constructed confirms
+      // to our naming requirement, i.e. [is] must be a dashed name and
+      // the tag name must not.
+      // if so, set isCustomElementName to false to kick off all the logics
+      // that pick up aIsAtom.
+      if (nsContentUtils::IsNameWithDash(aIsAtom) &&
+          !nsContentUtils::IsNameWithDash(name)) {
+        isCustomElementName = false;
+      } else {
+        isCustomElementName =
+            nsContentUtils::IsCustomElementName(name, kNameSpaceID_XUL);
+      }
+    } else {
+      isCustomElementName =
+          nsContentUtils::IsCustomElementName(name, kNameSpaceID_XUL);
+    }
+  }
+
+  nsAtom* tagAtom = nodeInfo->NameAtom();
+  nsAtom* typeAtom = nullptr;
+  bool isCustomElement = isCustomElementName || aIsAtom;
+  if (isCustomElement) {
+    typeAtom = isCustomElementName ? tagAtom : aIsAtom;
+  }
+
+  MOZ_ASSERT_IF(aDefinition, isCustomElement);
+
+  // https://dom.spec.whatwg.org/#concept-create-element
+  // We only handle the "synchronous custom elements flag is set" now.
+  // For the unset case (e.g. cloning a node), see bug 1319342 for that.
+  // Step 4.
+  RefPtr<CustomElementDefinition> definition = aDefinition;
+  if (isCustomElement && !definition) {
+    MOZ_ASSERT(nodeInfo->NameAtom()->Equals(nodeInfo->LocalName()));
+    definition = nsContentUtils::LookupCustomElementDefinition(
+        nodeInfo->GetDocument(), nodeInfo->NameAtom(), nodeInfo->NamespaceID(),
+        typeAtom);
+  }
+
+  // It might be a problem that parser synchronously calls constructor, so filed
+  // bug 1378079 to figure out what we should do for parser case.
+  if (definition) {
+    /*
+     * Synchronous custom elements flag is determined by 3 places in spec,
+     * 1) create an element for a token, the flag is determined by
+     *    "will execute script" which is not originally created
+     *    for the HTML fragment parsing algorithm.
+     * 2) createElement and createElementNS, the flag is the same as
+     *    NOT_FROM_PARSER.
+     * 3) clone a node, our implementation will not go into this function.
+     * For the unset case which is non-synchronous only applied for
+     * inner/outerHTML.
+     */
+    bool synchronousCustomElements = aFromParser != dom::FROM_PARSER_FRAGMENT;
+    // Per discussion in https://github.com/w3c/webcomponents/issues/635,
+    // use entry global in those places that are called from JS APIs and use the
+    // node document's global object if it is called from parser.
+    nsIGlobalObject* global;
+    if (aFromParser == dom::NOT_FROM_PARSER) {
+      global = GetEntryGlobal();
+
+      // Documents created from the PrototypeDocumentSink always use
+      // NOT_FROM_PARSER for non-XUL elements. We can get the global from the
+      // document in that case.
+      if (!global) {
+        Document* doc = nodeInfo->GetDocument();
+        if (doc && doc->LoadedFromPrototype()) {
+          global = doc->GetScopeObject();
+        }
+      }
+    } else {
+      global = nodeInfo->GetDocument()->GetScopeObject();
+    }
+    if (!global) {
+      // In browser chrome code, one may have access to a document which doesn't
+      // have scope object anymore.
+      return NS_ERROR_FAILURE;
+    }
+
+    AutoAllowLegacyScriptExecution exemption;
+    AutoEntryScript aes(global, "create custom elements");
+    JSContext* cx = aes.cx();
+    ErrorResult rv;
+
+    // Step 5.
+    if (definition->IsCustomBuiltIn()) {
+      // SetupCustomElement() should be called with an element that don't have
+      // CustomElementData setup, if not we will hit the assertion in
+      // SetCustomElementData().
+      // Built-in element
+      if (nodeInfo->NamespaceEquals(kNameSpaceID_XHTML)) {
+        *aResult =
+            CreateHTMLElement(tag, nodeInfo.forget(), aFromParser).take();
+      } else {
+        NS_IF_ADDREF(*aResult = nsXULElement::Construct(nodeInfo.forget()));
+      }
+      (*aResult)->SetCustomElementData(MakeUnique<CustomElementData>(typeAtom));
+      if (synchronousCustomElements) {
+        CustomElementRegistry::Upgrade(*aResult, definition, rv);
+        if (rv.MaybeSetPendingException(cx)) {
+          aes.ReportException();
+        }
+      } else {
+        nsContentUtils::EnqueueUpgradeReaction(*aResult, definition);
+      }
+
+      return NS_OK;
+    }
+
+    // Step 6.1.
+    if (synchronousCustomElements) {
+      definition->mPrefixStack.AppendElement(nodeInfo->GetPrefixAtom());
+      RefPtr<Document> doc = nodeInfo->GetDocument();
+      DoCustomElementCreate(aResult, cx, doc, nodeInfo,
+                            MOZ_KnownLive(definition->mConstructor), rv);
+      if (rv.MaybeSetPendingException(cx)) {
+        if (nodeInfo->NamespaceEquals(kNameSpaceID_XHTML)) {
+          NS_IF_ADDREF(*aResult = NS_NewHTMLUnknownElement(nodeInfo.forget(),
+                                                           aFromParser));
+        } else {
+          NS_IF_ADDREF(*aResult = nsXULElement::Construct(nodeInfo.forget()));
+        }
+        (*aResult)->SetDefined(false);
+      }
+      definition->mPrefixStack.RemoveLastElement();
+      return NS_OK;
+    }
+
+    // Step 6.2.
+    if (nodeInfo->NamespaceEquals(kNameSpaceID_XHTML)) {
+      NS_IF_ADDREF(*aResult =
+                       NS_NewHTMLElement(nodeInfo.forget(), aFromParser));
+    } else {
+      NS_IF_ADDREF(*aResult = nsXULElement::Construct(nodeInfo.forget()));
+    }
+    (*aResult)->SetCustomElementData(
+        MakeUnique<CustomElementData>(definition->mType));
+    nsContentUtils::EnqueueUpgradeReaction(*aResult, definition);
+    return NS_OK;
+  }
+
+  if (nodeInfo->NamespaceEquals(kNameSpaceID_XHTML)) {
+    // Per the Custom Element specification, unknown tags that are valid custom
+    // element names should be HTMLElement instead of HTMLUnknownElement.
+    if (isCustomElementName) {
+      NS_IF_ADDREF(*aResult =
+                       NS_NewHTMLElement(nodeInfo.forget(), aFromParser));
+    } else {
+      *aResult = CreateHTMLElement(tag, nodeInfo.forget(), aFromParser).take();
+    }
+  } else {
+    NS_IF_ADDREF(*aResult = nsXULElement::Construct(nodeInfo.forget()));
+  }
+
+  if (!*aResult) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  if (isCustomElement) {
+    (*aResult)->SetCustomElementData(MakeUnique<CustomElementData>(typeAtom));
+    nsContentUtils::RegisterCallbackUpgradeElement(*aResult, typeAtom);
+  }
+
+  return NS_OK;
+}
+
+CustomElementRegistry* nsContentUtils::GetCustomElementRegistry(
+    Document* aDoc) {
+  MOZ_ASSERT(aDoc);
+
+  if (!aDoc->GetDocShell()) {
+    return nullptr;
+  }
+
+  nsPIDOMWindowInner* window = aDoc->GetInnerWindow();
+  if (!window) {
+    return nullptr;
+  }
+
+  return window->CustomElements();
+}
+
+/* static */
+CustomElementDefinition* nsContentUtils::LookupCustomElementDefinition(
+    Document* aDoc, nsAtom* aNameAtom, uint32_t aNameSpaceID,
+    nsAtom* aTypeAtom) {
+  if (aNameSpaceID != kNameSpaceID_XUL && aNameSpaceID != kNameSpaceID_XHTML) {
+    return nullptr;
+  }
+
+  RefPtr<CustomElementRegistry> registry = GetCustomElementRegistry(aDoc);
+  if (!registry) {
+    return nullptr;
+  }
+
+  return registry->LookupCustomElementDefinition(aNameAtom, aNameSpaceID,
+                                                 aTypeAtom);
+}
+
+/* static */
+void nsContentUtils::RegisterCallbackUpgradeElement(Element* aElement,
+                                                    nsAtom* aTypeName) {
+  MOZ_ASSERT(aElement);
+
+  Document* doc = aElement->OwnerDoc();
+  CustomElementRegistry* registry = GetCustomElementRegistry(doc);
+  if (registry) {
+    registry->RegisterCallbackUpgradeElement(aElement, aTypeName);
+  }
+}
+
+/* static */
+void nsContentUtils::RegisterUnresolvedElement(Element* aElement,
+                                               nsAtom* aTypeName) {
+  MOZ_ASSERT(aElement);
+
+  Document* doc = aElement->OwnerDoc();
+  CustomElementRegistry* registry = GetCustomElementRegistry(doc);
+  if (registry) {
+    registry->RegisterUnresolvedElement(aElement, aTypeName);
+  }
+}
+
+/* static */
+void nsContentUtils::UnregisterUnresolvedElement(Element* aElement) {
+  MOZ_ASSERT(aElement);
+
+  nsAtom* typeAtom = aElement->GetCustomElementData()->GetCustomElementType();
+  Document* doc = aElement->OwnerDoc();
+  CustomElementRegistry* registry = GetCustomElementRegistry(doc);
+  if (registry) {
+    registry->UnregisterUnresolvedElement(aElement, typeAtom);
+  }
+}
+
+/* static */
+void nsContentUtils::EnqueueUpgradeReaction(
+    Element* aElement, CustomElementDefinition* aDefinition) {
+  MOZ_ASSERT(aElement);
+
+  Document* doc = aElement->OwnerDoc();
+
+  // No DocGroup means no custom element reactions stack.
+  if (!doc->GetDocGroup()) {
+    return;
+  }
+
+  CustomElementReactionsStack* stack =
+      doc->GetDocGroup()->CustomElementReactionsStack();
+  stack->EnqueueUpgradeReaction(aElement, aDefinition);
+}
+
+/* static */
+void nsContentUtils::EnqueueLifecycleCallback(
+    ElementCallbackType aType, Element* aCustomElement,
+    const LifecycleCallbackArgs& aArgs, CustomElementDefinition* aDefinition) {
+  // No DocGroup means no custom element reactions stack.
+  if (!aCustomElement->OwnerDoc()->GetDocGroup()) {
+    return;
+  }
+
+  CustomElementRegistry::EnqueueLifecycleCallback(aType, aCustomElement, aArgs,
+                                                  aDefinition);
+}
+
+/* static */
+void nsContentUtils::AppendDocumentLevelNativeAnonymousContentTo(
+    Document* aDocument, nsTArray<nsIContent*>& aElements) {
+  MOZ_ASSERT(aDocument);
+#ifdef DEBUG
+  size_t oldLength = aElements.Length();
+#endif
+
+  if (PresShell* presShell = aDocument->GetPresShell()) {
+    if (nsIFrame* scrollFrame = presShell->GetRootScrollFrame()) {
+      nsIAnonymousContentCreator* creator = do_QueryFrame(scrollFrame);
+      MOZ_ASSERT(
+          creator,
+          "scroll frame should always implement nsIAnonymousContentCreator");
+      creator->AppendAnonymousContentTo(aElements, 0);
+    }
+    if (nsCanvasFrame* canvasFrame = presShell->GetCanvasFrame()) {
+      canvasFrame->AppendAnonymousContentTo(aElements, 0);
+    }
+  }
+
+#ifdef DEBUG
+  for (size_t i = oldLength; i < aElements.Length(); i++) {
+    MOZ_ASSERT(
+        aElements[i]->GetProperty(nsGkAtoms::docLevelNativeAnonymousContent),
+        "Someone here has lied, or missed to flag the node");
+  }
+#endif
+}
+
+static void AppendNativeAnonymousChildrenFromFrame(nsIFrame* aFrame,
+                                                   nsTArray<nsIContent*>& aKids,
+                                                   uint32_t aFlags) {
+  if (nsIAnonymousContentCreator* ac = do_QueryFrame(aFrame)) {
+    ac->AppendAnonymousContentTo(aKids, aFlags);
+  }
+}
+
+/* static */
+void nsContentUtils::AppendNativeAnonymousChildren(const nsIContent* aContent,
+                                                   nsTArray<nsIContent*>& aKids,
+                                                   uint32_t aFlags) {
+  if (aContent->MayHaveAnonymousChildren()) {
+    if (nsIFrame* primaryFrame = aContent->GetPrimaryFrame()) {
+      // NAC created by the element's primary frame.
+      AppendNativeAnonymousChildrenFromFrame(primaryFrame, aKids, aFlags);
+
+      // NAC created by any other non-primary frames for the element.
+      AutoTArray<nsIFrame::OwnedAnonBox, 8> ownedAnonBoxes;
+      primaryFrame->AppendOwnedAnonBoxes(ownedAnonBoxes);
+      for (nsIFrame::OwnedAnonBox& box : ownedAnonBoxes) {
+        MOZ_ASSERT(box.mAnonBoxFrame->GetContent() == aContent);
+        AppendNativeAnonymousChildrenFromFrame(box.mAnonBoxFrame, aKids,
+                                               aFlags);
+      }
+    }
+
+    // Get manually created NAC (editor resize handles, etc.).
+    if (auto nac = static_cast<ManualNACArray*>(
+            aContent->GetProperty(nsGkAtoms::manualNACProperty))) {
+      aKids.AppendElements(*nac);
+    }
+  }
+
+  // The root scroll frame is not the primary frame of the root element.
+  // Detect and handle this case.
+  if (!(aFlags & nsIContent::eSkipDocumentLevelNativeAnonymousContent) &&
+      aContent == aContent->OwnerDoc()->GetRootElement()) {
+    AppendDocumentLevelNativeAnonymousContentTo(aContent->OwnerDoc(), aKids);
+  }
+}
+
+bool nsContentUtils::IsImageAvailable(nsIContent* aLoadingNode, nsIURI* aURI,
+                                      nsIPrincipal* aDefaultTriggeringPrincipal,
+                                      CORSMode aCORSMode) {
+  nsCOMPtr<nsIPrincipal> triggeringPrincipal;
+  QueryTriggeringPrincipal(aLoadingNode, aDefaultTriggeringPrincipal,
+                           getter_AddRefs(triggeringPrincipal));
+  MOZ_ASSERT(triggeringPrincipal);
+
+  Document* doc = aLoadingNode->OwnerDoc();
+  return IsImageAvailable(aURI, triggeringPrincipal, aCORSMode, doc);
+}
+
+bool nsContentUtils::IsImageAvailable(nsIURI* aURI,
+                                      nsIPrincipal* aTriggeringPrincipal,
+                                      CORSMode aCORSMode, Document* aDoc) {
+  imgLoader* imgLoader = GetImgLoaderForDocument(aDoc);
+  return imgLoader->IsImageAvailable(aURI, aTriggeringPrincipal, aCORSMode,
+                                     aDoc);
+}
+
+/* static */
+bool nsContentUtils::QueryTriggeringPrincipal(
+    nsIContent* aLoadingNode, nsIPrincipal* aDefaultPrincipal,
+    nsIPrincipal** aTriggeringPrincipal) {
+  MOZ_ASSERT(aLoadingNode);
+  MOZ_ASSERT(aTriggeringPrincipal);
+
+  bool result = false;
+  nsCOMPtr<nsIPrincipal> loadingPrincipal = aDefaultPrincipal;
+  if (!loadingPrincipal) {
+    loadingPrincipal = aLoadingNode->NodePrincipal();
+  }
+
+  // If aLoadingNode is content, bail out early.
+  if (!aLoadingNode->NodePrincipal()->IsSystemPrincipal()) {
+    loadingPrincipal.forget(aTriggeringPrincipal);
+    return result;
+  }
+
+  nsAutoString loadingStr;
+  if (aLoadingNode->IsElement()) {
+    aLoadingNode->AsElement()->GetAttr(
+        kNameSpaceID_None, nsGkAtoms::triggeringprincipal, loadingStr);
+  }
+
+  // Fall back if 'triggeringprincipal' isn't specified,
+  if (loadingStr.IsEmpty()) {
+    loadingPrincipal.forget(aTriggeringPrincipal);
+    return result;
+  }
+
+  nsCString binary;
+  nsCOMPtr<nsIPrincipal> serializedPrin =
+      BasePrincipal::FromJSON(NS_ConvertUTF16toUTF8(loadingStr));
+  if (serializedPrin) {
+    result = true;
+    serializedPrin.forget(aTriggeringPrincipal);
+  }
+
+  if (!result) {
+    // Fallback if the deserialization is failed.
+    loadingPrincipal.forget(aTriggeringPrincipal);
+  }
+
+  return result;
+}
+
+/* static */
+void nsContentUtils::GetContentPolicyTypeForUIImageLoading(
+    nsIContent* aLoadingNode, nsIPrincipal** aTriggeringPrincipal,
+    nsContentPolicyType& aContentPolicyType, uint64_t* aRequestContextID) {
+  MOZ_ASSERT(aRequestContextID);
+
+  bool result = QueryTriggeringPrincipal(aLoadingNode, aTriggeringPrincipal);
+  if (result) {
+    // Set the content policy type to TYPE_INTERNAL_IMAGE_FAVICON for
+    // indicating it's a favicon loading.
+    aContentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON;
+
+    nsAutoString requestContextID;
+    if (aLoadingNode->IsElement()) {
+      aLoadingNode->AsElement()->GetAttr(
+          kNameSpaceID_None, nsGkAtoms::requestcontextid, requestContextID);
+    }
+    nsresult rv;
+    int64_t val = requestContextID.ToInteger64(&rv);
+    *aRequestContextID = NS_SUCCEEDED(rv) ? val : 0;
+  } else {
+    aContentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE;
+  }
+}
+
+/* static */
+nsresult nsContentUtils::CreateJSValueFromSequenceOfObject(
+    JSContext* aCx, const Sequence<JSObject*>& aTransfer,
+    JS::MutableHandle<JS::Value> aValue) {
+  if (aTransfer.IsEmpty()) {
+    return NS_OK;
+  }
+
+  JS::Rooted<JSObject*> array(aCx, JS::NewArrayObject(aCx, aTransfer.Length()));
+  if (!array) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  for (uint32_t i = 0; i < aTransfer.Length(); ++i) {
+    JS::Rooted<JSObject*> object(aCx, aTransfer[i]);
+    if (!object) {
+      continue;
+    }
+
+    if (NS_WARN_IF(
+            !JS_DefineElement(aCx, array, i, object, JSPROP_ENUMERATE))) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  aValue.setObject(*array);
+  return NS_OK;
+}
+
+/* static */
+void nsContentUtils::StructuredClone(JSContext* aCx, nsIGlobalObject* aGlobal,
+                                     JS::Handle<JS::Value> aValue,
+                                     const StructuredSerializeOptions& aOptions,
+                                     JS::MutableHandle<JS::Value> aRetval,
+                                     ErrorResult& aError) {
+  JS::Rooted<JS::Value> transferArray(aCx, JS::UndefinedValue());
+  aError = nsContentUtils::CreateJSValueFromSequenceOfObject(
+      aCx, aOptions.mTransfer, &transferArray);
+  if (NS_WARN_IF(aError.Failed())) {
+    return;
+  }
+
+  JS::CloneDataPolicy clonePolicy;
+  // We are definitely staying in the same agent cluster.
+  clonePolicy.allowIntraClusterClonableSharedObjects();
+  if (aGlobal->IsSharedMemoryAllowed()) {
+    clonePolicy.allowSharedMemoryObjects();
+  }
+
+  StructuredCloneHolder holder(StructuredCloneHolder::CloningSupported,
+                               StructuredCloneHolder::TransferringSupported,
+                               JS::StructuredCloneScope::SameProcess);
+  holder.Write(aCx, aValue, transferArray, clonePolicy, aError);
+  if (NS_WARN_IF(aError.Failed())) {
+    return;
+  }
+
+  holder.Read(aGlobal, aCx, aRetval, clonePolicy, aError);
+  if (NS_WARN_IF(aError.Failed())) {
+    return;
+  }
+
+  nsTArray<RefPtr<MessagePort>> ports = holder.TakeTransferredPorts();
+  Unused << ports;
+}
+
+/* static */
+bool nsContentUtils::ShouldBlockReservedKeys(WidgetKeyboardEvent* aKeyEvent) {
+  nsCOMPtr<nsIPrincipal> principal;
+  RefPtr<Element> targetElement =
+      Element::FromEventTargetOrNull(aKeyEvent->mOriginalTarget);
+  nsCOMPtr<nsIBrowser> targetBrowser;
+  if (targetElement) {
+    targetBrowser = targetElement->AsBrowser();
+  }
+  bool isRemoteBrowser = false;
+  if (targetBrowser) {
+    targetBrowser->GetIsRemoteBrowser(&isRemoteBrowser);
+  }
+
+  if (isRemoteBrowser) {
+    targetBrowser->GetContentPrincipal(getter_AddRefs(principal));
+    return principal ? nsContentUtils::IsSitePermDeny(principal, "shortcuts"_ns)
+                     : false;
+  }
+
+  if (targetElement) {
+    Document* doc = targetElement->GetUncomposedDoc();
+    if (doc) {
+      RefPtr<WindowContext> wc = doc->GetWindowContext();
+      if (wc) {
+        return wc->TopWindowContext()->GetShortcutsPermission() ==
+               nsIPermissionManager::DENY_ACTION;
+      }
+    }
+  }
+
+  return false;
+}
+
+/**
+ * Checks whether the given type is a supported document type for
+ * loading within the nsObjectLoadingContent specified by aContent.
+ *
+ * NOTE Helper method for nsContentUtils::HtmlObjectContentTypeForMIMEType.
+ * NOTE Does not take content policy or capabilities into account
+ */
+static bool HtmlObjectContentSupportsDocument(const nsCString& aMimeType) {
+  nsCOMPtr<nsIWebNavigationInfo> info(
+      do_GetService(NS_WEBNAVIGATION_INFO_CONTRACTID));
+  if (!info) {
+    return false;
+  }
+
+  uint32_t supported;
+  nsresult rv = info->IsTypeSupported(aMimeType, &supported);
+
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  if (supported != nsIWebNavigationInfo::UNSUPPORTED) {
+    // Don't want to support plugins as documents
+    return supported != nsIWebNavigationInfo::FALLBACK;
+  }
+
+  // Try a stream converter
+  // NOTE: We treat any type we can convert from as a supported type. If a
+  // type is not actually supported, the URI loader will detect that and
+  // return an error, and we'll fallback.
+  nsCOMPtr<nsIStreamConverterService> convServ =
+      do_GetService("@mozilla.org/streamConverters;1");
+  bool canConvert = false;
+  if (convServ) {
+    rv = convServ->CanConvert(aMimeType.get(), "*/*", &canConvert);
+  }
+  return NS_SUCCEEDED(rv) && canConvert;
+}
+
+/* static */
+already_AddRefed<nsIPluginTag> nsContentUtils::PluginTagForType(
+    const nsCString& aMIMEType, bool aNoFakePlugin) {
+  RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+  nsCOMPtr<nsIPluginTag> tag;
+  NS_ENSURE_TRUE(pluginHost, nullptr);
+
+  // ShouldPlay will handle the case where the plugin is disabled
+  pluginHost->GetPluginTagForType(
+      aMIMEType,
+      aNoFakePlugin ? nsPluginHost::eExcludeFake : nsPluginHost::eExcludeNone,
+      getter_AddRefs(tag));
+
+  return tag.forget();
+}
+
+/* static */
+uint32_t nsContentUtils::HtmlObjectContentTypeForMIMEType(
+    const nsCString& aMIMEType, bool aNoFakePlugin) {
+  if (aMIMEType.IsEmpty()) {
+    return nsIObjectLoadingContent::TYPE_NULL;
+  }
+
+  if (imgLoader::SupportImageWithMimeType(aMIMEType)) {
+    return ResolveObjectType(nsIObjectLoadingContent::TYPE_IMAGE);
+  }
+
+  // Faking support of the PDF content as a document for EMBED tags
+  // when internal PDF viewer is enabled.
+  if (aMIMEType.LowerCaseEqualsLiteral("application/pdf") && IsPDFJSEnabled()) {
+    return nsIObjectLoadingContent::TYPE_DOCUMENT;
+  }
+
+  if (HtmlObjectContentSupportsDocument(aMIMEType)) {
+    return nsIObjectLoadingContent::TYPE_DOCUMENT;
+  }
+
+  bool isSpecialPlugin = nsPluginHost::GetSpecialType(aMIMEType) !=
+                         nsPluginHost::eSpecialType_None;
+  if (isSpecialPlugin) {
+    return nsIObjectLoadingContent::TYPE_FALLBACK;
+  }
+
+  return nsIObjectLoadingContent::TYPE_NULL;
+}
+
+/* static */
+already_AddRefed<nsISerialEventTarget> nsContentUtils::GetEventTargetByLoadInfo(
+    nsILoadInfo* aLoadInfo, TaskCategory aCategory) {
+  if (NS_WARN_IF(!aLoadInfo)) {
+    return nullptr;
+  }
+
+  RefPtr<Document> doc;
+  aLoadInfo->GetLoadingDocument(getter_AddRefs(doc));
+  nsCOMPtr<nsISerialEventTarget> target;
+  if (doc) {
+    if (DocGroup* group = doc->GetDocGroup()) {
+      target = group->EventTargetFor(aCategory);
+    }
+  } else {
+    target = GetMainThreadSerialEventTarget();
+  }
+
+  return target.forget();
+}
+
+/* static */
+bool nsContentUtils::IsLocalRefURL(const nsAString& aString) {
+  return !aString.IsEmpty() && aString[0] == '#';
+}
+
+// We use only 53 bits for the ID so that it can be converted to and from a JS
+// value without loss of precision. The upper bits of the ID hold the process
+// ID. The lower bits identify the object itself.
+static constexpr uint64_t kIdTotalBits = 53;
+static constexpr uint64_t kIdProcessBits = 22;
+static constexpr uint64_t kIdBits = kIdTotalBits - kIdProcessBits;
+
+/* static */
+uint64_t nsContentUtils::GenerateProcessSpecificId(uint64_t aId) {
+  uint64_t processId = 0;
+  if (XRE_IsContentProcess()) {
+    ContentChild* cc = ContentChild::GetSingleton();
+    processId = cc->GetID();
+  }
+
+  MOZ_RELEASE_ASSERT(processId < (uint64_t(1) << kIdProcessBits));
+  uint64_t processBits = processId & ((uint64_t(1) << kIdProcessBits) - 1);
+
+  uint64_t id = aId;
+  MOZ_RELEASE_ASSERT(id < (uint64_t(1) << kIdBits));
+  uint64_t bits = id & ((uint64_t(1) << kIdBits) - 1);
+
+  return (processBits << kIdBits) | bits;
+}
+
+/* static */
+std::tuple<uint64_t, uint64_t> nsContentUtils::SplitProcessSpecificId(
+    uint64_t aId) {
+  return {aId >> kIdBits, aId & ((uint64_t(1) << kIdBits) - 1)};
+}
+
+// Next process-local Tab ID.
+static uint64_t gNextTabId = 0;
+
+/* static */
+uint64_t nsContentUtils::GenerateTabId() {
+  return GenerateProcessSpecificId(++gNextTabId);
+}
+
+// Next process-local Browser ID.
+static uint64_t gNextBrowserId = 0;
+
+/* static */
+uint64_t nsContentUtils::GenerateBrowserId() {
+  return GenerateProcessSpecificId(++gNextBrowserId);
+}
+
+// Next process-local Browsing Context ID.
+static uint64_t gNextBrowsingContextId = 0;
+
+/* static */
+uint64_t nsContentUtils::GenerateBrowsingContextId() {
+  return GenerateProcessSpecificId(++gNextBrowsingContextId);
+}
+
+// Next process-local Window ID.
+static uint64_t gNextWindowId = 0;
+
+/* static */
+uint64_t nsContentUtils::GenerateWindowId() {
+  return GenerateProcessSpecificId(++gNextWindowId);
+}
+
+// Next process-local load.
+static Atomic<uint64_t> gNextLoadIdentifier(0);
+
+/* static */
+uint64_t nsContentUtils::GenerateLoadIdentifier() {
+  return GenerateProcessSpecificId(++gNextLoadIdentifier);
+}
+
+/* static */
+bool nsContentUtils::GetUserIsInteracting() {
+  return UserInteractionObserver::sUserActive;
+}
+
+/* static */
+bool nsContentUtils::GetSourceMapURL(nsIHttpChannel* aChannel,
+                                     nsACString& aResult) {
+  nsresult rv = aChannel->GetResponseHeader("SourceMap"_ns, aResult);
+  if (NS_FAILED(rv)) {
+    rv = aChannel->GetResponseHeader("X-SourceMap"_ns, aResult);
+  }
+  return NS_SUCCEEDED(rv);
+}
+
+/* static */
+bool nsContentUtils::IsMessageInputEvent(const IPC::Message& aMsg) {
+  if ((aMsg.type() & mozilla::dom::PBrowser::PBrowserStart) ==
+      mozilla::dom::PBrowser::PBrowserStart) {
+    switch (aMsg.type()) {
+      case mozilla::dom::PBrowser::Msg_RealMouseMoveEvent__ID:
+      case mozilla::dom::PBrowser::Msg_RealMouseButtonEvent__ID:
+      case mozilla::dom::PBrowser::Msg_RealMouseEnterExitWidgetEvent__ID:
+      case mozilla::dom::PBrowser::Msg_RealKeyEvent__ID:
+      case mozilla::dom::PBrowser::Msg_MouseWheelEvent__ID:
+      case mozilla::dom::PBrowser::Msg_RealTouchEvent__ID:
+      case mozilla::dom::PBrowser::Msg_RealTouchMoveEvent__ID:
+      case mozilla::dom::PBrowser::Msg_RealDragEvent__ID:
+      case mozilla::dom::PBrowser::Msg_UpdateDimensions__ID:
+        return true;
+    }
+  }
+  return false;
+}
+
+/* static */
+bool nsContentUtils::IsMessageCriticalInputEvent(const IPC::Message& aMsg) {
+  if ((aMsg.type() & mozilla::dom::PBrowser::PBrowserStart) ==
+      mozilla::dom::PBrowser::PBrowserStart) {
+    switch (aMsg.type()) {
+      case mozilla::dom::PBrowser::Msg_RealMouseButtonEvent__ID:
+      case mozilla::dom::PBrowser::Msg_RealKeyEvent__ID:
+      case mozilla::dom::PBrowser::Msg_MouseWheelEvent__ID:
+      case mozilla::dom::PBrowser::Msg_RealTouchEvent__ID:
+      case mozilla::dom::PBrowser::Msg_RealDragEvent__ID:
+        return true;
+    }
+  }
+  return false;
+}
+
+static const char* kUserInteractionInactive = "user-interaction-inactive";
+static const char* kUserInteractionActive = "user-interaction-active";
+
+void nsContentUtils::UserInteractionObserver::Init() {
+  // Listen for the observer messages from EventStateManager which are telling
+  // us whether or not the user is interacting.
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  obs->AddObserver(this, kUserInteractionInactive, false);
+  obs->AddObserver(this, kUserInteractionActive, false);
+
+  // We can't register ourselves as an annotator yet, as the
+  // BackgroundHangMonitor hasn't started yet. It will have started by the
+  // time we have the chance to spin the event loop.
+  RefPtr<UserInteractionObserver> self = this;
+  NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "nsContentUtils::UserInteractionObserver::Init",
+      [=]() { BackgroundHangMonitor::RegisterAnnotator(*self); }));
+}
+
+void nsContentUtils::UserInteractionObserver::Shutdown() {
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (obs) {
+    obs->RemoveObserver(this, kUserInteractionInactive);
+    obs->RemoveObserver(this, kUserInteractionActive);
+  }
+
+  BackgroundHangMonitor::UnregisterAnnotator(*this);
+}
+
+/**
+ * NB: This function is always called by the BackgroundHangMonitor thread.
+ *     Plan accordingly
+ */
+void nsContentUtils::UserInteractionObserver::AnnotateHang(
+    BackgroundHangAnnotations& aAnnotations) {
+  // NOTE: Only annotate the hang report if the user is known to be interacting.
+  if (sUserActive) {
+    aAnnotations.AddAnnotation(u"UserInteracting"_ns, true);
+  }
+}
+
+NS_IMETHODIMP
+nsContentUtils::UserInteractionObserver::Observe(nsISupports* aSubject,
+                                                 const char* aTopic,
+                                                 const char16_t* aData) {
+  if (!strcmp(aTopic, kUserInteractionInactive)) {
+    if (sUserActive && XRE_IsParentProcess()) {
+      glean::RecordPowerMetrics();
+    }
+    sUserActive = false;
+  } else if (!strcmp(aTopic, kUserInteractionActive)) {
+    if (!sUserActive && XRE_IsParentProcess()) {
+      glean::RecordPowerMetrics();
+
+      nsCOMPtr<nsIUserIdleServiceInternal> idleService =
+          do_GetService("@mozilla.org/widget/useridleservice;1");
+      if (idleService) {
+        idleService->ResetIdleTimeOut(0);
+      }
+    }
+
+    sUserActive = true;
+  } else {
+    NS_WARNING("Unexpected observer notification");
+  }
+  return NS_OK;
+}
+
+Atomic<bool> nsContentUtils::UserInteractionObserver::sUserActive(false);
+NS_IMPL_ISUPPORTS(nsContentUtils::UserInteractionObserver, nsIObserver)
+
+/* static */
+bool nsContentUtils::IsSpecialName(const nsAString& aName) {
+  return aName.LowerCaseEqualsLiteral("_blank") ||
+         aName.LowerCaseEqualsLiteral("_top") ||
+         aName.LowerCaseEqualsLiteral("_parent") ||
+         aName.LowerCaseEqualsLiteral("_self");
+}
+
+/* static */
+bool nsContentUtils::IsOverridingWindowName(const nsAString& aName) {
+  return !aName.IsEmpty() && !IsSpecialName(aName);
+}
+
+// Unfortunately, we can't unwrap an IDL object using only a concrete type.
+// We need to calculate type data based on the IDL typename. Which means
+// wrapping our templated function in a macro.
+#define EXTRACT_EXN_VALUES(T, ...)                                \
+  ExtractExceptionValues<mozilla::dom::prototypes::id::T,         \
+                         T##_Binding::NativeType, T>(__VA_ARGS__) \
+      .isOk()
+
+template <prototypes::ID PrototypeID, class NativeType, typename T>
+static Result<Ok, nsresult> ExtractExceptionValues(
+    JSContext* aCx, JS::Handle<JSObject*> aObj, nsAString& aSourceSpecOut,
+    uint32_t* aLineOut, uint32_t* aColumnOut, nsString& aMessageOut) {
+  AssertStaticUnwrapOK<PrototypeID>();
+  RefPtr<T> exn;
+  MOZ_TRY((UnwrapObject<PrototypeID, NativeType>(aObj, exn, nullptr)));
+
+  exn->GetFilename(aCx, aSourceSpecOut);
+  if (!aSourceSpecOut.IsEmpty()) {
+    *aLineOut = exn->LineNumber(aCx);
+    *aColumnOut = exn->ColumnNumber();
+  }
+
+  exn->GetName(aMessageOut);
+  aMessageOut.AppendLiteral(": ");
+
+  nsAutoString message;
+  exn->GetMessageMoz(message);
+  aMessageOut.Append(message);
+  return Ok();
+}
+
+/* static */
+void nsContentUtils::ExtractErrorValues(
+    JSContext* aCx, JS::Handle<JS::Value> aValue, nsACString& aSourceSpecOut,
+    uint32_t* aLineOut, uint32_t* aColumnOut, nsString& aMessageOut) {
+  nsAutoString sourceSpec;
+  ExtractErrorValues(aCx, aValue, sourceSpec, aLineOut, aColumnOut,
+                     aMessageOut);
+  CopyUTF16toUTF8(sourceSpec, aSourceSpecOut);
+}
+
+/* static */
+void nsContentUtils::ExtractErrorValues(
+    JSContext* aCx, JS::Handle<JS::Value> aValue, nsAString& aSourceSpecOut,
+    uint32_t* aLineOut, uint32_t* aColumnOut, nsString& aMessageOut) {
+  MOZ_ASSERT(aLineOut);
+  MOZ_ASSERT(aColumnOut);
+
+  if (aValue.isObject()) {
+    JS::Rooted<JSObject*> obj(aCx, &aValue.toObject());
+
+    // Try to process as an Error object.  Use the file/line/column values
+    // from the Error as they will be more specific to the root cause of
+    // the problem.
+    JSErrorReport* err = obj ? JS_ErrorFromException(aCx, obj) : nullptr;
+    if (err) {
+      // Use xpc to extract the error message only.  We don't actually send
+      // this report anywhere.
+      RefPtr<xpc::ErrorReport> report = new xpc::ErrorReport();
+      report->Init(err,
+                   nullptr,  // toString result
+                   false,    // chrome
+                   0);       // window ID
+
+      if (!report->mFileName.IsEmpty()) {
+        aSourceSpecOut = report->mFileName;
+        *aLineOut = report->mLineNumber;
+        *aColumnOut = report->mColumn;
+      }
+      aMessageOut.Assign(report->mErrorMsg);
+    }
+
+    // Next, try to unwrap the rejection value as a DOMException.
+    else if (EXTRACT_EXN_VALUES(DOMException, aCx, obj, aSourceSpecOut,
+                                aLineOut, aColumnOut, aMessageOut)) {
+      return;
+    }
+
+    // Next, try to unwrap the rejection value as an XPC Exception.
+    else if (EXTRACT_EXN_VALUES(Exception, aCx, obj, aSourceSpecOut, aLineOut,
+                                aColumnOut, aMessageOut)) {
+      return;
+    }
+  }
+
+  // If we could not unwrap a specific error type, then perform default safe
+  // string conversions on primitives.  Objects will result in "[Object]"
+  // unfortunately.
+  if (aMessageOut.IsEmpty()) {
+    nsAutoJSString jsString;
+    if (jsString.init(aCx, aValue)) {
+      aMessageOut = jsString;
+    } else {
+      JS_ClearPendingException(aCx);
+    }
+  }
+}
+
+#undef EXTRACT_EXN_VALUES
+
+/* static */
+bool nsContentUtils::ContentIsLink(nsIContent* aContent) {
+  if (!aContent || !aContent->IsElement()) {
+    return false;
+  }
+
+  if (aContent->IsHTMLElement(nsGkAtoms::a)) {
+    return true;
+  }
+
+  return aContent->AsElement()->AttrValueIs(kNameSpaceID_XLink, nsGkAtoms::type,
+                                            nsGkAtoms::simple, eCaseMatters);
+}
+
+/* static */
+already_AddRefed<ContentFrameMessageManager>
+nsContentUtils::TryGetBrowserChildGlobal(nsISupports* aFrom) {
+  RefPtr<nsFrameLoaderOwner> frameLoaderOwner = do_QueryObject(aFrom);
+  if (!frameLoaderOwner) {
+    return nullptr;
+  }
+
+  RefPtr<nsFrameLoader> frameLoader = frameLoaderOwner->GetFrameLoader();
+  if (!frameLoader) {
+    return nullptr;
+  }
+
+  RefPtr<ContentFrameMessageManager> manager =
+      frameLoader->GetBrowserChildMessageManager();
+  return manager.forget();
+}
+
+/* static */
+uint32_t nsContentUtils::InnerOrOuterWindowCreated() {
+  MOZ_ASSERT(NS_IsMainThread());
+  ++sInnerOrOuterWindowCount;
+  return ++sInnerOrOuterWindowSerialCounter;
+}
+
+/* static */
+void nsContentUtils::InnerOrOuterWindowDestroyed() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(sInnerOrOuterWindowCount > 0);
+  --sInnerOrOuterWindowCount;
+}
+
+/* static */
+nsresult nsContentUtils::AnonymizeURI(nsIURI* aURI, nsCString& aAnonymizedURI) {
+  MOZ_ASSERT(aURI);
+
+  if (aURI->SchemeIs("data")) {
+    aAnonymizedURI.Assign("data:..."_ns);
+    return NS_OK;
+  }
+  // Anonymize the URL.
+  // Strip the URL of any possible username/password and make it ready to be
+  // presented in the UI.
+  nsCOMPtr<nsIURI> exposableURI = net::nsIOService::CreateExposableURI(aURI);
+  return exposableURI->GetSpec(aAnonymizedURI);
+}
+
+static bool JSONCreator(const char16_t* aBuf, uint32_t aLen, void* aData) {
+  nsAString* result = static_cast<nsAString*>(aData);
+  result->Append(aBuf, aLen);
+  return true;
+}
+
+/* static */
+bool nsContentUtils::StringifyJSON(JSContext* aCx, JS::Handle<JS::Value> aValue,
+                                   nsAString& aOutStr, JSONBehavior aBehavior) {
+  MOZ_ASSERT(aCx);
+  switch (aBehavior) {
+    case UndefinedIsNullStringLiteral: {
+      aOutStr.Truncate();
+      JS::Rooted<JS::Value> value(aCx, aValue);
+      nsAutoString serializedValue;
+      NS_ENSURE_TRUE(JS_Stringify(aCx, &value, nullptr, JS::NullHandleValue,
+                                  JSONCreator, &serializedValue),
+                     false);
+      aOutStr = serializedValue;
+      return true;
+    }
+    case UndefinedIsVoidString: {
+      aOutStr.SetIsVoid(true);
+      return JS::ToJSON(aCx, aValue, nullptr, JS::NullHandleValue, JSONCreator,
+                        &aOutStr);
+    }
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid value for aBehavior");
+      return false;
+  }
+}
+
+/* static */
+bool nsContentUtils::
+    HighPriorityEventPendingForTopLevelDocumentBeforeContentfulPaint(
+        Document* aDocument) {
+  MOZ_ASSERT(XRE_IsContentProcess(),
+             "This function only makes sense in content processes");
+
+  if (aDocument && !aDocument->IsLoadedAsData()) {
+    if (nsPresContext* presContext = FindPresContextForDocument(aDocument)) {
+      MOZ_ASSERT(!presContext->IsChrome(),
+                 "Should never have a chrome PresContext in a content process");
+
+      return !presContext->GetInProcessRootContentDocumentPresContext()
+                  ->HadFirstContentfulPaint() &&
+             nsThreadManager::MainThreadHasPendingHighPriorityEvents();
+    }
+  }
+  return false;
+}
+
+static nsGlobalWindowInner* GetInnerWindowForGlobal(nsIGlobalObject* aGlobal) {
+  NS_ENSURE_TRUE(aGlobal, nullptr);
+
+  if (auto* window = aGlobal->AsInnerWindow()) {
+    return nsGlobalWindowInner::Cast(window);
+  }
+
+  // When Extensions run content scripts inside a sandbox, it uses
+  // sandboxPrototype to make them appear as though they're running in the
+  // scope of the page. So when a content script invokes postMessage, it expects
+  // the |source| of the received message to be the window set as the
+  // sandboxPrototype. This used to work incidentally for unrelated reasons, but
+  // now we need to do some special handling to support it.
+  JS::Rooted<JSObject*> scope(RootingCx(), aGlobal->GetGlobalJSObject());
+  NS_ENSURE_TRUE(scope, nullptr);
+
+  if (xpc::IsSandbox(scope)) {
+    AutoJSAPI jsapi;
+    MOZ_ALWAYS_TRUE(jsapi.Init(scope));
+    JSContext* cx = jsapi.cx();
+    // Our current Realm on aCx is the sandbox.  Using that for unwrapping
+    // makes sense: if the sandbox can unwrap the window, we can use it.
+    return xpc::SandboxWindowOrNull(scope, cx);
+  }
+
+  // The calling window must be holding a reference, so we can return a weak
+  // pointer.
+  return nsGlobalWindowInner::Cast(aGlobal->AsInnerWindow());
+}
+
+/* static */
+nsGlobalWindowInner* nsContentUtils::IncumbentInnerWindow() {
+  return GetInnerWindowForGlobal(GetIncumbentGlobal());
+}
+
+/* static */
+nsGlobalWindowInner* nsContentUtils::EntryInnerWindow() {
+  return GetInnerWindowForGlobal(GetEntryGlobal());
+}
+
+/* static */
+bool nsContentUtils::IsURIInPrefList(nsIURI* aURI, const char* aPrefName) {
+  MOZ_ASSERT(aPrefName);
+
+  nsAutoCString list;
+  Preferences::GetCString(aPrefName, list);
+  ToLowerCase(list);
+  return IsURIInList(aURI, list);
+}
+
+/* static */
+bool nsContentUtils::IsURIInList(nsIURI* aURI, const nsCString& aList) {
+#ifdef DEBUG
+  nsAutoCString listLowerCase(aList);
+  ToLowerCase(listLowerCase);
+  MOZ_ASSERT(listLowerCase.Equals(aList),
+             "The aList argument should be lower-case");
+#endif
+
+  if (!aURI) {
+    return false;
+  }
+
+  nsAutoCString scheme;
+  aURI->GetScheme(scheme);
+  if (!scheme.EqualsLiteral("http") && !scheme.EqualsLiteral("https")) {
+    return false;
+  }
+
+  if (aList.IsEmpty()) {
+    return false;
+  }
+
+  // The list is comma separated domain list.  Each item may start with "*.".
+  // If starts with "*.", it matches any sub-domains.
+
+  nsCCharSeparatedTokenizer tokenizer(aList, ',');
+  while (tokenizer.hasMoreTokens()) {
+    const nsCString token(tokenizer.nextToken());
+
+    nsAutoCString host;
+    aURI->GetHost(host);
+    if (host.IsEmpty()) {
+      return false;
+    }
+    ToLowerCase(host);
+
+    for (;;) {
+      int32_t index = token.Find(host);
+      if (index >= 0 &&
+          static_cast<uint32_t>(index) + host.Length() <= token.Length()) {
+        // If we found a full match, return true.
+        size_t indexAfterHost = index + host.Length();
+        if (index == 0 && indexAfterHost == token.Length()) {
+          return true;
+        }
+        // If next character is '/', we need to check the path too.
+        // We assume the path in the list means "/foo" + "*".
+        if (token[indexAfterHost] == '/') {
+          nsDependentCSubstring pathInList(
+              token, indexAfterHost,
+              static_cast<nsDependentCSubstring::size_type>(-1));
+          nsAutoCString filePath;
+          aURI->GetFilePath(filePath);
+          ToLowerCase(filePath);
+          if (StringBeginsWith(filePath, pathInList) &&
+              (filePath.Length() == pathInList.Length() ||
+               pathInList.EqualsLiteral("/") ||
+               filePath[pathInList.Length() - 1] == '/' ||
+               filePath[pathInList.Length() - 1] == '?' ||
+               filePath[pathInList.Length() - 1] == '#')) {
+            return true;
+          }
+        }
+      }
+      int32_t startIndexOfCurrentLevel = host[0] == '*' ? 1 : 0;
+      int32_t startIndexOfNextLevel =
+          host.Find(".", startIndexOfCurrentLevel + 1);
+      if (startIndexOfNextLevel <= 0) {
+        break;
+      }
+      host = "*"_ns + nsDependentCSubstring(host, startIndexOfNextLevel);
+    }
+  }
+
+  return false;
+}
+
+/* static */
+ScreenIntMargin nsContentUtils::GetWindowSafeAreaInsets(
+    nsIScreen* aScreen, const ScreenIntMargin& aSafeAreaInsets,
+    const LayoutDeviceIntRect& aWindowRect) {
+  // This calculates safe area insets of window from screen rectangle, window
+  // rectangle and safe area insets of screen.
+  //
+  // +----------------------------------------+ <-- screen
+  // |  +-------------------------------+  <------- window
+  // |  | window's safe area inset top) |     |
+  // +--+-------------------------------+--+  |
+  // |  |                               |  |<------ safe area rectangle of
+  // |  |                               |  |  |     screen
+  // +--+-------------------------------+--+  |
+  // |  |window's safe area inset bottom|     |
+  // |  +-------------------------------+     |
+  // +----------------------------------------+
+  //
+  ScreenIntMargin windowSafeAreaInsets;
+
+  if (windowSafeAreaInsets == aSafeAreaInsets) {
+    // no safe area insets.
+    return windowSafeAreaInsets;
+  }
+
+  int32_t screenLeft, screenTop, screenWidth, screenHeight;
+  nsresult rv =
+      aScreen->GetRect(&screenLeft, &screenTop, &screenWidth, &screenHeight);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return windowSafeAreaInsets;
+  }
+
+  const ScreenIntRect screenRect(screenLeft, screenTop, screenWidth,
+                                 screenHeight);
+
+  ScreenIntRect safeAreaRect = screenRect;
+  safeAreaRect.Deflate(aSafeAreaInsets);
+
+  ScreenIntRect windowRect = ViewAs<ScreenPixel>(
+      aWindowRect, PixelCastJustification::LayoutDeviceIsScreenForTabDims);
+
+  // FIXME(bug 1754323): This can trigger because the screen rect is not
+  // orientation-aware.
+  // MOZ_ASSERT(screenRect.Contains(windowRect),
+  //            "Screen doesn't contain window rect? Something seems off");
+
+  // window's rect of safe area
+  safeAreaRect = safeAreaRect.Intersect(windowRect);
+
+  windowSafeAreaInsets.top = safeAreaRect.y - aWindowRect.y;
+  windowSafeAreaInsets.left = safeAreaRect.x - aWindowRect.x;
+  windowSafeAreaInsets.right =
+      aWindowRect.x + aWindowRect.width - (safeAreaRect.x + safeAreaRect.width);
+  windowSafeAreaInsets.bottom = aWindowRect.y + aWindowRect.height -
+                                (safeAreaRect.y + safeAreaRect.height);
+
+  windowSafeAreaInsets.EnsureAtLeast(ScreenIntMargin());
+  // This shouldn't be needed, but it wallpapers orientation issues, see bug
+  // 1754323.
+  windowSafeAreaInsets.EnsureAtMost(aSafeAreaInsets);
+
+  return windowSafeAreaInsets;
+}
+
+/* static */
+nsContentUtils::SubresourceCacheValidationInfo
+nsContentUtils::GetSubresourceCacheValidationInfo(nsIRequest* aRequest,
+                                                  nsIURI* aURI) {
+  SubresourceCacheValidationInfo info;
+  if (nsCOMPtr<nsICacheInfoChannel> cache = do_QueryInterface(aRequest)) {
+    uint32_t value = 0;
+    if (NS_SUCCEEDED(cache->GetCacheTokenExpirationTime(&value))) {
+      info.mExpirationTime.emplace(value);
+    }
+  }
+
+  // Determine whether the cache entry must be revalidated when we try to use
+  // it. Currently, only HTTP specifies this information...
+  if (nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aRequest)) {
+    Unused << httpChannel->IsNoStoreResponse(&info.mMustRevalidate);
+
+    if (!info.mMustRevalidate) {
+      Unused << httpChannel->IsNoCacheResponse(&info.mMustRevalidate);
+    }
+  }
+
+  // data: URIs are safe to cache across documents under any circumstance, so we
+  // special-case them here even though the channel itself doesn't have any
+  // caching policy. Same for chrome:// uris.
+  //
+  // TODO(emilio): Figure out which other schemes that don't have caching
+  // policies are safe to cache. Blobs should be...
+  const bool knownCacheable = [&] {
+    if (!aURI) {
+      return false;
+    }
+    if (aURI->SchemeIs("data") || aURI->SchemeIs("moz-page-thumb") ||
+        aURI->SchemeIs("moz-extension")) {
+      return true;
+    }
+    if (aURI->SchemeIs("chrome") || aURI->SchemeIs("resource")) {
+      return !StaticPrefs::nglayout_debug_disable_xul_cache();
+    }
+    return false;
+  }();
+
+  if (knownCacheable) {
+    MOZ_ASSERT(!info.mExpirationTime);
+    MOZ_ASSERT(!info.mMustRevalidate);
+    info.mExpirationTime = Some(0);  // 0 means "doesn't expire".
+  }
+
+  return info;
+}
+
+nsCString nsContentUtils::TruncatedURLForDisplay(nsIURI* aURL, size_t aMaxLen) {
+  nsCString spec;
+  if (aURL) {
+    aURL->GetSpec(spec);
+    spec.Truncate(std::min(aMaxLen, spec.Length()));
+  }
+  return spec;
+}
+
+/* static */
+nsresult nsContentUtils::AnonymizeId(nsAString& aId,
+                                     const nsACString& aOriginKey,
+                                     OriginFormat aFormat) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  nsresult rv;
+  nsCString rawKey;
+  if (aFormat == OriginFormat::Base64) {
+    rv = Base64Decode(aOriginKey, rawKey);
+    NS_ENSURE_SUCCESS(rv, rv);
+  } else {
+    rawKey = aOriginKey;
+  }
+
+  HMAC hmac;
+  rv = hmac.Begin(
+      SEC_OID_SHA256,
+      Span(reinterpret_cast<const uint8_t*>(rawKey.get()), rawKey.Length()));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  NS_ConvertUTF16toUTF8 id(aId);
+  rv = hmac.Update(reinterpret_cast<const uint8_t*>(id.get()), id.Length());
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsTArray<uint8_t> macBytes;
+  rv = hmac.End(macBytes);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCString macBase64;
+  rv = Base64Encode(
+      nsDependentCSubstring(reinterpret_cast<const char*>(macBytes.Elements()),
+                            macBytes.Length()),
+      macBase64);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  CopyUTF8toUTF16(macBase64, aId);
+  return NS_OK;
+}
+
+/* static */
+bool nsContentUtils::ShouldHideObjectOrEmbedImageDocument() {
+  return StaticPrefs::
+             browser_opaqueResponseBlocking_syntheticBrowsingContext_AtStartup() &&
+         StaticPrefs::
+             browser_opaqueResponseBlocking_syntheticBrowsingContext_filter_AtStartup_DoNotUseDirectly();
+}
+
+/* static */
+uint32_t nsContentUtils::ResolveObjectType(uint32_t aType) {
+  if (!StaticPrefs::
+          browser_opaqueResponseBlocking_syntheticBrowsingContext_AtStartup()) {
+    return aType;
+  }
+
+  if (aType != nsIObjectLoadingContent::TYPE_IMAGE) {
+    return aType;
+  }
+
+  return nsIObjectLoadingContent::TYPE_DOCUMENT;
+}
+
+void nsContentUtils::RequestGeckoTaskBurst() {
+  nsCOMPtr<nsIAppShell> appShell = do_GetService(NS_APPSHELL_CID);
+  if (appShell) {
+    appShell->GeckoTaskBurst();
+  }
+}
+
+nsIContent* nsContentUtils::GetClosestLinkInFlatTree(nsIContent* aContent) {
+  for (nsIContent* content = aContent; content;
+       content = content->GetFlattenedTreeParent()) {
+    if (nsContentUtils::IsDraggableLink(content)) {
+      return content;
+    }
+  }
+  return nullptr;
+}
+
+namespace mozilla {
+std::ostream& operator<<(std::ostream& aOut,
+                         const PreventDefaultResult aPreventDefaultResult) {
+  switch (aPreventDefaultResult) {
+    case PreventDefaultResult::No:
+      aOut << "unhandled";
+      break;
+    case PreventDefaultResult::ByContent:
+      aOut << "handled-by-content";
+      break;
+    case PreventDefaultResult::ByChrome:
+      aOut << "handled-by-chrome";
+      break;
+  }
+  return aOut;
+}
+}  // namespace mozilla