Adding upstream version 110.0.1.upstream/110.0.1upstream

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

1 files changed, 6695 insertions, 0 deletions

diff --git a/dom/events/EventStateManager.cpp b/dom/events/EventStateManager.cpp
new file mode 100644
index 0000000000..92fca9a6e9
--- /dev/null
+++ b/dom/events/EventStateManager.cpp
@@ -0,0 +1,6695 @@
+/* -*- 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/. */
+
+#include "EventStateManager.h"
+
+#include "mozilla/AsyncEventDispatcher.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/EditorBase.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/Hal.h"
+#include "mozilla/HTMLEditor.h"
+#include "mozilla/IMEStateManager.h"
+#include "mozilla/MiscEvents.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/PointerLockManager.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/ScrollTypes.h"
+#include "mozilla/TextComposition.h"
+#include "mozilla/TextControlElement.h"
+#include "mozilla/TextEditor.h"
+#include "mozilla/TextEvents.h"
+#include "mozilla/TouchEvents.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/dom/BrowserBridgeChild.h"
+#include "mozilla/dom/BrowsingContext.h"
+#include "mozilla/dom/CanonicalBrowsingContext.h"
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/DOMIntersectionObserver.h"
+#include "mozilla/dom/DragEvent.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/dom/FrameLoaderBinding.h"
+#include "mozilla/dom/HTMLLabelElement.h"
+#include "mozilla/dom/MouseEventBinding.h"
+#include "mozilla/dom/BrowserChild.h"
+#include "mozilla/dom/PointerEventHandler.h"
+#include "mozilla/dom/UIEvent.h"
+#include "mozilla/dom/UIEventBinding.h"
+#include "mozilla/dom/UserActivation.h"
+#include "mozilla/dom/WheelEventBinding.h"
+#include "mozilla/glean/GleanMetrics.h"
+#include "mozilla/StaticPrefs_accessibility.h"
+#include "mozilla/StaticPrefs_browser.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/StaticPrefs_layout.h"
+#include "mozilla/StaticPrefs_mousewheel.h"
+#include "mozilla/StaticPrefs_plugin.h"
+#include "mozilla/StaticPrefs_ui.h"
+#include "mozilla/StaticPrefs_zoom.h"
+
+#include "ContentEventHandler.h"
+#include "IMEContentObserver.h"
+#include "WheelHandlingHelper.h"
+#include "RemoteDragStartData.h"
+
+#include "nsCommandParams.h"
+#include "nsCOMPtr.h"
+#include "nsCopySupport.h"
+#include "nsFocusManager.h"
+#include "nsGenericHTMLElement.h"
+#include "nsIClipboard.h"
+#include "nsIContent.h"
+#include "nsIContentInlines.h"
+#include "mozilla/dom/Document.h"
+#include "nsICookieJarSettings.h"
+#include "nsIFrame.h"
+#include "nsFrameLoaderOwner.h"
+#include "nsIWidget.h"
+#include "nsLiteralString.h"
+#include "nsPresContext.h"
+#include "nsGkAtoms.h"
+#include "nsIFormControl.h"
+#include "nsComboboxControlFrame.h"
+#include "nsIScrollableFrame.h"
+#include "nsIDOMXULControlElement.h"
+#include "nsNameSpaceManager.h"
+#include "nsIBaseWindow.h"
+#include "nsFrameSelection.h"
+#include "nsPIDOMWindow.h"
+#include "nsPIWindowRoot.h"
+#include "nsIWebNavigation.h"
+#include "nsIContentViewer.h"
+#include "nsFrameManager.h"
+#include "nsIBrowserChild.h"
+#include "nsMenuPopupFrame.h"
+
+#include "nsIObserverService.h"
+#include "nsIDocShell.h"
+
+#include "nsSubDocumentFrame.h"
+#include "nsLayoutUtils.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsUnicharUtils.h"
+#include "nsContentUtils.h"
+
+#include "imgIContainer.h"
+#include "nsIProperties.h"
+#include "nsISupportsPrimitives.h"
+
+#include "nsServiceManagerUtils.h"
+#include "nsITimer.h"
+#include "nsFontMetrics.h"
+#include "nsIDragService.h"
+#include "nsIDragSession.h"
+#include "mozilla/dom/DataTransfer.h"
+#include "nsContentAreaDragDrop.h"
+#include "nsTreeBodyFrame.h"
+#include "nsIController.h"
+#include "mozilla/Services.h"
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/dom/Record.h"
+#include "mozilla/dom/Selection.h"
+
+#include "mozilla/Preferences.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/ProfilerLabels.h"
+#include "Units.h"
+
+#ifdef XP_MACOSX
+#  import <ApplicationServices/ApplicationServices.h>
+#endif
+
+namespace mozilla {
+
+using namespace dom;
+
+static const LayoutDeviceIntPoint kInvalidRefPoint =
+    LayoutDeviceIntPoint(-1, -1);
+
+static uint32_t gMouseOrKeyboardEventCounter = 0;
+static nsITimer* gUserInteractionTimer = nullptr;
+static nsITimerCallback* gUserInteractionTimerCallback = nullptr;
+
+static const double kCursorLoadingTimeout = 1000;  // ms
+static AutoWeakFrame gLastCursorSourceFrame;
+static TimeStamp gLastCursorUpdateTime;
+static TimeStamp gTypingStartTime;
+static TimeStamp gTypingEndTime;
+static int32_t gTypingInteractionKeyPresses = 0;
+static dom::InteractionData gTypingInteraction = {};
+
+static inline int32_t RoundDown(double aDouble) {
+  return (aDouble > 0) ? static_cast<int32_t>(floor(aDouble))
+                       : static_cast<int32_t>(ceil(aDouble));
+}
+
+static UniquePtr<WidgetMouseEvent> CreateMouseOrPointerWidgetEvent(
+    WidgetMouseEvent* aMouseEvent, EventMessage aMessage,
+    EventTarget* aRelatedTarget);
+
+/******************************************************************/
+/* mozilla::UITimerCallback                                       */
+/******************************************************************/
+
+class UITimerCallback final : public nsITimerCallback, public nsINamed {
+ public:
+  UITimerCallback() : mPreviousCount(0) {}
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSITIMERCALLBACK
+  NS_DECL_NSINAMED
+ private:
+  ~UITimerCallback() = default;
+  uint32_t mPreviousCount;
+};
+
+NS_IMPL_ISUPPORTS(UITimerCallback, nsITimerCallback, nsINamed)
+
+// If aTimer is nullptr, this method always sends "user-interaction-inactive"
+// notification.
+NS_IMETHODIMP
+UITimerCallback::Notify(nsITimer* aTimer) {
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (!obs) return NS_ERROR_FAILURE;
+  if ((gMouseOrKeyboardEventCounter == mPreviousCount) || !aTimer) {
+    gMouseOrKeyboardEventCounter = 0;
+    obs->NotifyObservers(nullptr, "user-interaction-inactive", nullptr);
+    if (gUserInteractionTimer) {
+      gUserInteractionTimer->Cancel();
+      NS_RELEASE(gUserInteractionTimer);
+    }
+  } else {
+    obs->NotifyObservers(nullptr, "user-interaction-active", nullptr);
+    EventStateManager::UpdateUserActivityTimer();
+
+    if (XRE_IsParentProcess()) {
+      hal::BatteryInformation batteryInfo;
+      hal::GetCurrentBatteryInformation(&batteryInfo);
+      glean::power_battery::percentage_when_user_active.AccumulateSamples(
+          {uint64_t(batteryInfo.level() * 100)});
+    }
+  }
+  mPreviousCount = gMouseOrKeyboardEventCounter;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+UITimerCallback::GetName(nsACString& aName) {
+  aName.AssignLiteral("UITimerCallback_timer");
+  return NS_OK;
+}
+
+/******************************************************************/
+/* mozilla::OverOutElementsWrapper                                */
+/******************************************************************/
+
+OverOutElementsWrapper::OverOutElementsWrapper() : mLastOverFrame(nullptr) {}
+
+OverOutElementsWrapper::~OverOutElementsWrapper() = default;
+
+NS_IMPL_CYCLE_COLLECTION(OverOutElementsWrapper, mLastOverElement,
+                         mFirstOverEventElement, mFirstOutEventElement)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(OverOutElementsWrapper)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(OverOutElementsWrapper)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(OverOutElementsWrapper)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+/******************************************************************/
+/* mozilla::EventStateManager                                     */
+/******************************************************************/
+
+static uint32_t sESMInstanceCount = 0;
+
+bool EventStateManager::sNormalLMouseEventInProcess = false;
+int16_t EventStateManager::sCurrentMouseBtn = MouseButton::eNotPressed;
+EventStateManager* EventStateManager::sActiveESM = nullptr;
+Document* EventStateManager::sMouseOverDocument = nullptr;
+AutoWeakFrame EventStateManager::sLastDragOverFrame = nullptr;
+LayoutDeviceIntPoint EventStateManager::sPreLockPoint =
+    LayoutDeviceIntPoint(0, 0);
+LayoutDeviceIntPoint EventStateManager::sLastRefPoint = kInvalidRefPoint;
+CSSIntPoint EventStateManager::sLastScreenPoint = CSSIntPoint(0, 0);
+LayoutDeviceIntPoint EventStateManager::sSynthCenteringPoint = kInvalidRefPoint;
+CSSIntPoint EventStateManager::sLastClientPoint = CSSIntPoint(0, 0);
+nsCOMPtr<nsIContent> EventStateManager::sDragOverContent = nullptr;
+
+EventStateManager::WheelPrefs* EventStateManager::WheelPrefs::sInstance =
+    nullptr;
+EventStateManager::DeltaAccumulator*
+    EventStateManager::DeltaAccumulator::sInstance = nullptr;
+
+constexpr const StyleCursorKind kInvalidCursorKind =
+    static_cast<StyleCursorKind>(255);
+
+EventStateManager::EventStateManager()
+    : mLockCursor(kInvalidCursorKind),
+      mLastFrameConsumedSetCursor(false),
+      mCurrentTarget(nullptr),
+      // init d&d gesture state machine variables
+      mGestureDownPoint(0, 0),
+      mGestureModifiers(0),
+      mGestureDownButtons(0),
+      mPresContext(nullptr),
+      mLClickCount(0),
+      mMClickCount(0),
+      mRClickCount(0),
+      mShouldAlwaysUseLineDeltas(false),
+      mShouldAlwaysUseLineDeltasInitialized(false),
+      mGestureDownInTextControl(false),
+      mInTouchDrag(false),
+      m_haveShutdown(false) {
+  if (sESMInstanceCount == 0) {
+    gUserInteractionTimerCallback = new UITimerCallback();
+    if (gUserInteractionTimerCallback) NS_ADDREF(gUserInteractionTimerCallback);
+    UpdateUserActivityTimer();
+  }
+  ++sESMInstanceCount;
+}
+
+nsresult EventStateManager::UpdateUserActivityTimer() {
+  if (!gUserInteractionTimerCallback) return NS_OK;
+
+  if (!gUserInteractionTimer) {
+    gUserInteractionTimer = NS_NewTimer().take();
+  }
+
+  if (gUserInteractionTimer) {
+    gUserInteractionTimer->InitWithCallback(
+        gUserInteractionTimerCallback,
+        StaticPrefs::dom_events_user_interaction_interval(),
+        nsITimer::TYPE_ONE_SHOT);
+  }
+  return NS_OK;
+}
+
+nsresult EventStateManager::Init() {
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (!observerService) return NS_ERROR_FAILURE;
+
+  observerService->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, true);
+
+  return NS_OK;
+}
+
+bool EventStateManager::ShouldAlwaysUseLineDeltas() {
+  if (MOZ_UNLIKELY(!mShouldAlwaysUseLineDeltasInitialized)) {
+    mShouldAlwaysUseLineDeltasInitialized = true;
+    mShouldAlwaysUseLineDeltas =
+        !StaticPrefs::dom_event_wheel_deltaMode_lines_disabled();
+    if (!mShouldAlwaysUseLineDeltas && mDocument) {
+      if (nsIPrincipal* principal =
+              mDocument->GetPrincipalForPrefBasedHacks()) {
+        mShouldAlwaysUseLineDeltas = principal->IsURIInPrefList(
+            "dom.event.wheel-deltaMode-lines.always-enabled");
+      }
+    }
+  }
+  return mShouldAlwaysUseLineDeltas;
+}
+
+EventStateManager::~EventStateManager() {
+  ReleaseCurrentIMEContentObserver();
+
+  if (sActiveESM == this) {
+    sActiveESM = nullptr;
+  }
+
+  if (StaticPrefs::ui_click_hold_context_menus()) {
+    KillClickHoldTimer();
+  }
+
+  if (mDocument == sMouseOverDocument) {
+    sMouseOverDocument = nullptr;
+  }
+
+  --sESMInstanceCount;
+  if (sESMInstanceCount == 0) {
+    WheelTransaction::Shutdown();
+    if (gUserInteractionTimerCallback) {
+      gUserInteractionTimerCallback->Notify(nullptr);
+      NS_RELEASE(gUserInteractionTimerCallback);
+    }
+    if (gUserInteractionTimer) {
+      gUserInteractionTimer->Cancel();
+      NS_RELEASE(gUserInteractionTimer);
+    }
+    WheelPrefs::Shutdown();
+    DeltaAccumulator::Shutdown();
+  }
+
+  if (sDragOverContent && sDragOverContent->OwnerDoc() == mDocument) {
+    sDragOverContent = nullptr;
+  }
+
+  if (!m_haveShutdown) {
+    Shutdown();
+
+    // Don't remove from Observer service in Shutdown because Shutdown also
+    // gets called from xpcom shutdown observer.  And we don't want to remove
+    // from the service in that case.
+
+    nsCOMPtr<nsIObserverService> observerService =
+        mozilla::services::GetObserverService();
+    if (observerService) {
+      observerService->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
+    }
+  }
+}
+
+nsresult EventStateManager::Shutdown() {
+  m_haveShutdown = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+EventStateManager::Observe(nsISupports* aSubject, const char* aTopic,
+                           const char16_t* someData) {
+  if (!nsCRT::strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
+    Shutdown();
+  }
+
+  return NS_OK;
+}
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(EventStateManager)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIObserver)
+  NS_INTERFACE_MAP_ENTRY(nsIObserver)
+  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(EventStateManager)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(EventStateManager)
+
+NS_IMPL_CYCLE_COLLECTION_WEAK(EventStateManager, mCurrentTargetContent,
+                              mGestureDownContent, mGestureDownFrameOwner,
+                              mLastLeftMouseDownContent,
+                              mLastMiddleMouseDownContent,
+                              mLastRightMouseDownContent, mActiveContent,
+                              mHoverContent, mURLTargetContent,
+                              mMouseEnterLeaveHelper, mPointersEnterLeaveHelper,
+                              mDocument, mIMEContentObserver, mAccessKeys)
+
+void EventStateManager::ReleaseCurrentIMEContentObserver() {
+  if (mIMEContentObserver) {
+    mIMEContentObserver->DisconnectFromEventStateManager();
+  }
+  mIMEContentObserver = nullptr;
+}
+
+void EventStateManager::OnStartToObserveContent(
+    IMEContentObserver* aIMEContentObserver) {
+  if (mIMEContentObserver == aIMEContentObserver) {
+    return;
+  }
+  ReleaseCurrentIMEContentObserver();
+  mIMEContentObserver = aIMEContentObserver;
+}
+
+void EventStateManager::OnStopObservingContent(
+    IMEContentObserver* aIMEContentObserver) {
+  aIMEContentObserver->DisconnectFromEventStateManager();
+  NS_ENSURE_TRUE_VOID(mIMEContentObserver == aIMEContentObserver);
+  mIMEContentObserver = nullptr;
+}
+
+void EventStateManager::TryToFlushPendingNotificationsToIME() {
+  if (mIMEContentObserver) {
+    mIMEContentObserver->TryToFlushPendingNotifications(true);
+  }
+}
+
+static bool IsMessageMouseUserActivity(EventMessage aMessage) {
+  return aMessage == eMouseMove || aMessage == eMouseUp ||
+         aMessage == eMouseDown || aMessage == eMouseAuxClick ||
+         aMessage == eMouseDoubleClick || aMessage == eMouseClick ||
+         aMessage == eMouseActivate || aMessage == eMouseLongTap;
+}
+
+static bool IsMessageGamepadUserActivity(EventMessage aMessage) {
+  return aMessage == eGamepadButtonDown || aMessage == eGamepadButtonUp ||
+         aMessage == eGamepadAxisMove;
+}
+
+// static
+bool EventStateManager::IsKeyboardEventUserActivity(WidgetEvent* aEvent) {
+  // We ignore things that shouldn't cause popups, but also things that look
+  // like shortcut presses. In some obscure cases these may actually be
+  // website input, but any meaningful website will have other input anyway,
+  // and we can't very well tell whether shortcut input was supposed to be
+  // directed at chrome or the document.
+
+  WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
+  // Access keys should be treated as page interaction.
+  if (keyEvent->ModifiersMatchWithAccessKey(AccessKeyType::eContent)) {
+    return true;
+  }
+  if (!keyEvent->CanTreatAsUserInput() || keyEvent->IsControl() ||
+      keyEvent->IsMeta() || keyEvent->IsOS() || keyEvent->IsAlt()) {
+    return false;
+  }
+  // Deal with function keys:
+  switch (keyEvent->mKeyNameIndex) {
+    case KEY_NAME_INDEX_F1:
+    case KEY_NAME_INDEX_F2:
+    case KEY_NAME_INDEX_F3:
+    case KEY_NAME_INDEX_F4:
+    case KEY_NAME_INDEX_F5:
+    case KEY_NAME_INDEX_F6:
+    case KEY_NAME_INDEX_F7:
+    case KEY_NAME_INDEX_F8:
+    case KEY_NAME_INDEX_F9:
+    case KEY_NAME_INDEX_F10:
+    case KEY_NAME_INDEX_F11:
+    case KEY_NAME_INDEX_F12:
+    case KEY_NAME_INDEX_F13:
+    case KEY_NAME_INDEX_F14:
+    case KEY_NAME_INDEX_F15:
+    case KEY_NAME_INDEX_F16:
+    case KEY_NAME_INDEX_F17:
+    case KEY_NAME_INDEX_F18:
+    case KEY_NAME_INDEX_F19:
+    case KEY_NAME_INDEX_F20:
+    case KEY_NAME_INDEX_F21:
+    case KEY_NAME_INDEX_F22:
+    case KEY_NAME_INDEX_F23:
+    case KEY_NAME_INDEX_F24:
+      return false;
+    default:
+      return true;
+  }
+}
+
+static void OnTypingInteractionEnded() {
+  // We don't consider a single keystroke to be typing.
+  if (gTypingInteractionKeyPresses > 1) {
+    gTypingInteraction.mInteractionCount += gTypingInteractionKeyPresses;
+    gTypingInteraction.mInteractionTimeInMilliseconds += static_cast<uint32_t>(
+        std::ceil((gTypingEndTime - gTypingStartTime).ToMilliseconds()));
+  }
+
+  gTypingInteractionKeyPresses = 0;
+  gTypingStartTime = TimeStamp();
+  gTypingEndTime = TimeStamp();
+}
+
+static void HandleKeyUpInteraction(WidgetKeyboardEvent* aKeyEvent) {
+  if (EventStateManager::IsKeyboardEventUserActivity(aKeyEvent)) {
+    TimeStamp now = TimeStamp::Now();
+    if (gTypingEndTime.IsNull()) {
+      gTypingEndTime = now;
+    }
+    TimeDuration delay = now - gTypingEndTime;
+    // Has it been too long since the last keystroke to be considered typing?
+    if (gTypingInteractionKeyPresses > 0 &&
+        delay >
+            TimeDuration::FromMilliseconds(
+                StaticPrefs::browser_places_interactions_typing_timeout_ms())) {
+      OnTypingInteractionEnded();
+    }
+    gTypingInteractionKeyPresses++;
+    if (gTypingStartTime.IsNull()) {
+      gTypingStartTime = now;
+    }
+    gTypingEndTime = now;
+  }
+}
+
+nsresult EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
+                                           WidgetEvent* aEvent,
+                                           nsIFrame* aTargetFrame,
+                                           nsIContent* aTargetContent,
+                                           nsEventStatus* aStatus,
+                                           nsIContent* aOverrideClickTarget) {
+  NS_ENSURE_ARG_POINTER(aStatus);
+  NS_ENSURE_ARG(aPresContext);
+  if (!aEvent) {
+    NS_ERROR("aEvent is null.  This should never happen.");
+    return NS_ERROR_NULL_POINTER;
+  }
+
+  NS_WARNING_ASSERTION(
+      !aTargetFrame || !aTargetFrame->GetContent() ||
+          aTargetFrame->GetContent() == aTargetContent ||
+          aTargetFrame->GetContent()->GetFlattenedTreeParent() ==
+              aTargetContent ||
+          aTargetFrame->IsGeneratedContentFrame(),
+      "aTargetFrame should be related with aTargetContent");
+#if DEBUG
+  if (aTargetFrame && aTargetFrame->IsGeneratedContentFrame()) {
+    nsCOMPtr<nsIContent> targetContent;
+    aTargetFrame->GetContentForEvent(aEvent, getter_AddRefs(targetContent));
+    MOZ_ASSERT(aTargetContent == targetContent,
+               "Unexpected target for generated content frame!");
+  }
+#endif
+
+  mCurrentTarget = aTargetFrame;
+  mCurrentTargetContent = nullptr;
+
+  // Do not take account eMouseEnterIntoWidget/ExitFromWidget so that loading
+  // a page when user is not active doesn't change the state to active.
+  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+  if (aEvent->IsTrusted() &&
+      ((mouseEvent && mouseEvent->IsReal() &&
+        IsMessageMouseUserActivity(mouseEvent->mMessage)) ||
+       aEvent->mClass == eWheelEventClass ||
+       aEvent->mClass == ePointerEventClass ||
+       aEvent->mClass == eTouchEventClass ||
+       aEvent->mClass == eKeyboardEventClass ||
+       (aEvent->mClass == eDragEventClass && aEvent->mMessage == eDrop) ||
+       IsMessageGamepadUserActivity(aEvent->mMessage))) {
+    if (gMouseOrKeyboardEventCounter == 0) {
+      nsCOMPtr<nsIObserverService> obs =
+          mozilla::services::GetObserverService();
+      if (obs) {
+        obs->NotifyObservers(nullptr, "user-interaction-active", nullptr);
+        UpdateUserActivityTimer();
+      }
+    }
+    ++gMouseOrKeyboardEventCounter;
+
+    nsCOMPtr<nsINode> node = aTargetContent;
+    if (node &&
+        ((aEvent->mMessage == eKeyUp && IsKeyboardEventUserActivity(aEvent)) ||
+         aEvent->mMessage == eMouseUp || aEvent->mMessage == eWheel ||
+         aEvent->mMessage == eTouchEnd || aEvent->mMessage == ePointerUp ||
+         aEvent->mMessage == eDrop)) {
+      Document* doc = node->OwnerDoc();
+      while (doc) {
+        doc->SetUserHasInteracted();
+        doc = nsContentUtils::IsChildOfSameType(doc)
+                  ? doc->GetInProcessParentDocument()
+                  : nullptr;
+      }
+    }
+  }
+
+  WheelTransaction::OnEvent(aEvent);
+
+  // Focus events don't necessarily need a frame.
+  if (!mCurrentTarget && !aTargetContent) {
+    NS_ERROR("mCurrentTarget and aTargetContent are null");
+    return NS_ERROR_NULL_POINTER;
+  }
+#ifdef DEBUG
+  if (aEvent->HasDragEventMessage() && PointerLockManager::IsLocked()) {
+    NS_ASSERTION(PointerLockManager::IsLocked(),
+                 "Pointer is locked. Drag events should be suppressed when "
+                 "the pointer is locked.");
+  }
+#endif
+  // Store last known screenPoint and clientPoint so pointer lock
+  // can use these values as constants.
+  if (aEvent->IsTrusted() &&
+      ((mouseEvent && mouseEvent->IsReal()) ||
+       aEvent->mClass == eWheelEventClass) &&
+      !PointerLockManager::IsLocked()) {
+    // XXX Probably doesn't matter much, but storing these in CSS pixels instead
+    // of device pixels means behavior can be a bit odd if you zoom while
+    // pointer-locked.
+    sLastScreenPoint =
+        Event::GetScreenCoords(aPresContext, aEvent, aEvent->mRefPoint)
+            .extract();
+    sLastClientPoint = Event::GetClientCoords(
+        aPresContext, aEvent, aEvent->mRefPoint, CSSIntPoint(0, 0));
+  }
+
+  *aStatus = nsEventStatus_eIgnore;
+
+  if (aEvent->mClass == eQueryContentEventClass) {
+    HandleQueryContentEvent(aEvent->AsQueryContentEvent());
+    return NS_OK;
+  }
+
+  WidgetTouchEvent* touchEvent = aEvent->AsTouchEvent();
+  if (touchEvent && mInTouchDrag) {
+    if (touchEvent->mMessage == eTouchMove) {
+      GenerateDragGesture(aPresContext, touchEvent);
+    } else {
+      mInTouchDrag = false;
+      StopTrackingDragGesture(true);
+    }
+  }
+
+  switch (aEvent->mMessage) {
+    case eContextMenu:
+      if (PointerLockManager::IsLocked()) {
+        return NS_ERROR_DOM_INVALID_STATE_ERR;
+      }
+      break;
+    case eMouseTouchDrag:
+      mInTouchDrag = true;
+      BeginTrackingDragGesture(aPresContext, mouseEvent, aTargetFrame);
+      break;
+    case eMouseDown: {
+      switch (mouseEvent->mButton) {
+        case MouseButton::ePrimary:
+          BeginTrackingDragGesture(aPresContext, mouseEvent, aTargetFrame);
+          mLClickCount = mouseEvent->mClickCount;
+          SetClickCount(mouseEvent, aStatus);
+          sNormalLMouseEventInProcess = true;
+          break;
+        case MouseButton::eMiddle:
+          mMClickCount = mouseEvent->mClickCount;
+          SetClickCount(mouseEvent, aStatus);
+          break;
+        case MouseButton::eSecondary:
+          mRClickCount = mouseEvent->mClickCount;
+          SetClickCount(mouseEvent, aStatus);
+          break;
+      }
+      NotifyTargetUserActivation(aEvent, aTargetContent);
+      break;
+    }
+    case eMouseUp: {
+      switch (mouseEvent->mButton) {
+        case MouseButton::ePrimary:
+          if (StaticPrefs::ui_click_hold_context_menus()) {
+            KillClickHoldTimer();
+          }
+          mInTouchDrag = false;
+          StopTrackingDragGesture(true);
+          sNormalLMouseEventInProcess = false;
+          // then fall through...
+          [[fallthrough]];
+        case MouseButton::eSecondary:
+        case MouseButton::eMiddle:
+          RefPtr<EventStateManager> esm =
+              ESMFromContentOrThis(aOverrideClickTarget);
+          esm->SetClickCount(mouseEvent, aStatus, aOverrideClickTarget);
+          break;
+      }
+      break;
+    }
+    case eMouseEnterIntoWidget:
+      PointerEventHandler::UpdateActivePointerState(mouseEvent, aTargetContent);
+      // In some cases on e10s eMouseEnterIntoWidget
+      // event was sent twice into child process of content.
+      // (From specific widget code (sending is not permanent) and
+      // from ESM::DispatchMouseOrPointerEvent (sending is permanent)).
+      // IsCrossProcessForwardingStopped() helps to suppress sending accidental
+      // event from widget code.
+      aEvent->StopCrossProcessForwarding();
+      break;
+    case eMouseExitFromWidget:
+      // If this is a remote frame, we receive eMouseExitFromWidget from the
+      // parent the mouse exits our content. Since the parent may update the
+      // cursor while the mouse is outside our frame, and since PuppetWidget
+      // caches the current cursor internally, re-entering our content (say from
+      // over a window edge) wont update the cursor if the cached value and the
+      // current cursor match. So when the mouse exits a remote frame, clear the
+      // cached widget cursor so a proper update will occur when the mouse
+      // re-enters.
+      if (XRE_IsContentProcess()) {
+        ClearCachedWidgetCursor(mCurrentTarget);
+      }
+
+      // IsCrossProcessForwardingStopped() helps to suppress double event
+      // sending into process of content. For more information see comment
+      // above, at eMouseEnterIntoWidget case.
+      aEvent->StopCrossProcessForwarding();
+
+      // If the event is not a top-level window or puppet widget exit, then it's
+      // not really an exit --- we may have traversed widget boundaries but
+      // we're still in our toplevel window or puppet widget.
+      if (mouseEvent->mExitFrom.value() !=
+              WidgetMouseEvent::ePlatformTopLevel &&
+          mouseEvent->mExitFrom.value() != WidgetMouseEvent::ePuppet) {
+        // Treat it as a synthetic move so we don't generate spurious
+        // "exit" or "move" events.  Any necessary "out" or "over" events
+        // will be generated by GenerateMouseEnterExit
+        mouseEvent->mMessage = eMouseMove;
+        mouseEvent->mReason = WidgetMouseEvent::eSynthesized;
+        // then fall through...
+      } else {
+        MOZ_ASSERT_IF(XRE_IsParentProcess(),
+                      mouseEvent->mExitFrom.value() ==
+                          WidgetMouseEvent::ePlatformTopLevel);
+        MOZ_ASSERT_IF(XRE_IsContentProcess(), mouseEvent->mExitFrom.value() ==
+                                                  WidgetMouseEvent::ePuppet);
+        // We should synthetize corresponding pointer events
+        GeneratePointerEnterExit(ePointerLeave, mouseEvent);
+        GenerateMouseEnterExit(mouseEvent);
+        // This is really an exit and should stop here
+        aEvent->mMessage = eVoidEvent;
+        break;
+      }
+      [[fallthrough]];
+    case eMouseMove:
+    case ePointerDown:
+      if (aEvent->mMessage == ePointerDown) {
+        PointerEventHandler::UpdateActivePointerState(mouseEvent,
+                                                      aTargetContent);
+        PointerEventHandler::ImplicitlyCapturePointer(aTargetFrame, aEvent);
+        if (mouseEvent->mInputSource != MouseEvent_Binding::MOZ_SOURCE_TOUCH) {
+          NotifyTargetUserActivation(aEvent, aTargetContent);
+        }
+      }
+      [[fallthrough]];
+    case ePointerMove: {
+      if (!mInTouchDrag &&
+          PointerEventHandler::IsDragAndDropEnabled(*mouseEvent)) {
+        GenerateDragGesture(aPresContext, mouseEvent);
+      }
+      // on the Mac, GenerateDragGesture() may not return until the drag
+      // has completed and so |aTargetFrame| may have been deleted (moving
+      // a bookmark, for example).  If this is the case, however, we know
+      // that ClearFrameRefs() has been called and it cleared out
+      // |mCurrentTarget|. As a result, we should pass |mCurrentTarget|
+      // into UpdateCursor().
+      UpdateCursor(aPresContext, aEvent, mCurrentTarget, aStatus);
+
+      UpdateLastRefPointOfMouseEvent(mouseEvent);
+      if (PointerLockManager::IsLocked()) {
+        ResetPointerToWindowCenterWhilePointerLocked(mouseEvent);
+      }
+      UpdateLastPointerPosition(mouseEvent);
+
+      GenerateMouseEnterExit(mouseEvent);
+      // Flush pending layout changes, so that later mouse move events
+      // will go to the right nodes.
+      FlushLayout(aPresContext);
+      break;
+    }
+    case ePointerGotCapture:
+      GenerateMouseEnterExit(mouseEvent);
+      break;
+    case eDragStart:
+      if (StaticPrefs::ui_click_hold_context_menus()) {
+        // an external drag gesture event came in, not generated internally
+        // by Gecko. Make sure we get rid of the click-hold timer.
+        KillClickHoldTimer();
+      }
+      break;
+    case eDragOver: {
+      WidgetDragEvent* dragEvent = aEvent->AsDragEvent();
+      MOZ_ASSERT(dragEvent);
+      if (dragEvent->mFlags.mIsSynthesizedForTests) {
+        dragEvent->InitDropEffectForTests();
+      }
+      // Send the enter/exit events before eDrop.
+      GenerateDragDropEnterExit(aPresContext, dragEvent);
+      break;
+    }
+    case eDrop:
+      if (aEvent->mFlags.mIsSynthesizedForTests) {
+        MOZ_ASSERT(aEvent->AsDragEvent());
+        aEvent->AsDragEvent()->InitDropEffectForTests();
+      }
+      break;
+
+    case eKeyPress: {
+      WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
+      if (keyEvent->ModifiersMatchWithAccessKey(AccessKeyType::eChrome) ||
+          keyEvent->ModifiersMatchWithAccessKey(AccessKeyType::eContent)) {
+        // If the eKeyPress event will be sent to a remote process, this
+        // process needs to wait reply from the remote process for checking if
+        // preceding eKeyDown event is consumed.  If preceding eKeyDown event
+        // is consumed in the remote process, BrowserChild won't send the event
+        // back to this process.  So, only when this process receives a reply
+        // eKeyPress event in BrowserParent, we should handle accesskey in this
+        // process.
+        if (IsTopLevelRemoteTarget(GetFocusedElement())) {
+          // However, if there is no accesskey target for the key combination,
+          // we don't need to wait reply from the remote process.  Otherwise,
+          // Mark the event as waiting reply from remote process and stop
+          // propagation in this process.
+          if (CheckIfEventMatchesAccessKey(keyEvent, aPresContext)) {
+            keyEvent->StopPropagation();
+            keyEvent->MarkAsWaitingReplyFromRemoteProcess();
+          }
+        }
+        // If the event target is in this process, we can handle accesskey now
+        // since if preceding eKeyDown event was consumed, eKeyPress event
+        // won't be dispatched by widget.  So, coming eKeyPress event means
+        // that the preceding eKeyDown event wasn't consumed in this case.
+        else {
+          AutoTArray<uint32_t, 10> accessCharCodes;
+          keyEvent->GetAccessKeyCandidates(accessCharCodes);
+
+          if (HandleAccessKey(keyEvent, aPresContext, accessCharCodes)) {
+            *aStatus = nsEventStatus_eConsumeNoDefault;
+          }
+        }
+      }
+    }
+      // then fall through...
+      [[fallthrough]];
+    case eKeyDown:
+      if (aEvent->mMessage == eKeyDown) {
+        NotifyTargetUserActivation(aEvent, aTargetContent);
+      }
+      [[fallthrough]];
+    case eKeyUp: {
+      Element* element = GetFocusedElement();
+      if (element) {
+        mCurrentTargetContent = element;
+      }
+
+      // NOTE: Don't refer TextComposition::IsComposing() since UI Events
+      //       defines that KeyboardEvent.isComposing is true when it's
+      //       dispatched after compositionstart and compositionend.
+      //       TextComposition::IsComposing() is false even before
+      //       compositionend if there is no composing string.
+      //       And also don't expose other document's composition state.
+      //       A native IME context is typically shared by multiple documents.
+      //       So, don't use GetTextCompositionFor(nsIWidget*) here.
+      RefPtr<TextComposition> composition =
+          IMEStateManager::GetTextCompositionFor(aPresContext);
+      aEvent->AsKeyboardEvent()->mIsComposing = !!composition;
+
+      // Widget may need to perform default action for specific keyboard
+      // event if it's not consumed.  In this case, widget has already marked
+      // the event as "waiting reply from remote process".  However, we need
+      // to reset it if the target (focused content) isn't in a remote process
+      // because PresShell needs to check if it's marked as so before
+      // dispatching events into the DOM tree.
+      if (aEvent->IsWaitingReplyFromRemoteProcess() &&
+          !aEvent->PropagationStopped() && !IsTopLevelRemoteTarget(element)) {
+        aEvent->ResetWaitingReplyFromRemoteProcessState();
+      }
+    } break;
+    case eWheel:
+    case eWheelOperationStart:
+    case eWheelOperationEnd: {
+      NS_ASSERTION(aEvent->IsTrusted(),
+                   "Untrusted wheel event shouldn't be here");
+      using DeltaModeCheckingState = WidgetWheelEvent::DeltaModeCheckingState;
+
+      if (Element* element = GetFocusedElement()) {
+        mCurrentTargetContent = element;
+      }
+
+      if (aEvent->mMessage != eWheel) {
+        break;
+      }
+
+      WidgetWheelEvent* wheelEvent = aEvent->AsWheelEvent();
+      WheelPrefs::GetInstance()->ApplyUserPrefsToDelta(wheelEvent);
+
+      // If we won't dispatch a DOM event for this event, nothing to do anymore.
+      if (!wheelEvent->IsAllowedToDispatchDOMEvent()) {
+        break;
+      }
+
+      if (StaticPrefs::dom_event_wheel_deltaMode_lines_always_disabled()) {
+        wheelEvent->mDeltaModeCheckingState = DeltaModeCheckingState::Unchecked;
+      } else if (ShouldAlwaysUseLineDeltas()) {
+        wheelEvent->mDeltaModeCheckingState = DeltaModeCheckingState::Checked;
+      } else {
+        wheelEvent->mDeltaModeCheckingState = DeltaModeCheckingState::Unknown;
+      }
+
+      // Init lineOrPageDelta values for line scroll events for some devices
+      // on some platforms which might dispatch wheel events which don't
+      // have lineOrPageDelta values.  And also, if delta values are
+      // customized by prefs, this recomputes them.
+      DeltaAccumulator::GetInstance()->InitLineOrPageDelta(aTargetFrame, this,
+                                                           wheelEvent);
+    } break;
+    case eSetSelection: {
+      RefPtr<Element> focuedElement = GetFocusedElement();
+      IMEStateManager::HandleSelectionEvent(aPresContext, focuedElement,
+                                            aEvent->AsSelectionEvent());
+      break;
+    }
+    case eContentCommandCut:
+    case eContentCommandCopy:
+    case eContentCommandPaste:
+    case eContentCommandDelete:
+    case eContentCommandUndo:
+    case eContentCommandRedo:
+    case eContentCommandPasteTransferable:
+    case eContentCommandLookUpDictionary:
+      DoContentCommandEvent(aEvent->AsContentCommandEvent());
+      break;
+    case eContentCommandInsertText:
+      DoContentCommandInsertTextEvent(aEvent->AsContentCommandEvent());
+      break;
+    case eContentCommandScroll:
+      DoContentCommandScrollEvent(aEvent->AsContentCommandEvent());
+      break;
+    case eCompositionStart:
+      if (aEvent->IsTrusted()) {
+        // If the event is trusted event, set the selected text to data of
+        // composition event.
+        WidgetCompositionEvent* compositionEvent = aEvent->AsCompositionEvent();
+        WidgetQueryContentEvent querySelectedTextEvent(
+            true, eQuerySelectedText, compositionEvent->mWidget);
+        HandleQueryContentEvent(&querySelectedTextEvent);
+        if (querySelectedTextEvent.FoundSelection()) {
+          compositionEvent->mData = querySelectedTextEvent.mReply->DataRef();
+        }
+        NS_ASSERTION(querySelectedTextEvent.Succeeded(),
+                     "Failed to get selected text");
+      }
+      break;
+    case eTouchStart:
+      SetGestureDownPoint(aEvent->AsTouchEvent());
+      break;
+    case eTouchEnd:
+      NotifyTargetUserActivation(aEvent, aTargetContent);
+      break;
+    default:
+      break;
+  }
+  return NS_OK;
+}
+
+void EventStateManager::NotifyTargetUserActivation(WidgetEvent* aEvent,
+                                                   nsIContent* aTargetContent) {
+  if (!aEvent->IsTrusted()) {
+    return;
+  }
+
+  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+  if (mouseEvent && !mouseEvent->IsReal()) {
+    return;
+  }
+
+  nsCOMPtr<nsINode> node = aTargetContent;
+  if (!node) {
+    return;
+  }
+
+  Document* doc = node->OwnerDoc();
+  if (!doc) {
+    return;
+  }
+
+  // Don't gesture activate for key events for keys which are likely
+  // to be interaction with the browser, OS.
+  WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
+  if (keyEvent && !keyEvent->CanUserGestureActivateTarget()) {
+    return;
+  }
+
+  // Touch gestures that end outside the drag target were touches that turned
+  // into scroll/pan/swipe actions. We don't want to gesture activate on such
+  // actions, we want to only gesture activate on touches that are taps.
+  // That is, touches that end in roughly the same place that they started.
+  if (aEvent->mMessage == eTouchEnd && aEvent->AsTouchEvent() &&
+      IsEventOutsideDragThreshold(aEvent->AsTouchEvent())) {
+    return;
+  }
+
+  // Do not treat the click on scrollbar as a user interaction with the web
+  // content.
+  if (StaticPrefs::dom_user_activation_ignore_scrollbars() &&
+      (aEvent->mMessage == eMouseDown || aEvent->mMessage == ePointerDown) &&
+      aTargetContent->IsInNativeAnonymousSubtree()) {
+    nsIContent* current = aTargetContent;
+    do {
+      nsIContent* root = current->GetClosestNativeAnonymousSubtreeRoot();
+      if (!root) {
+        break;
+      }
+      if (root->IsXULElement(nsGkAtoms::scrollbar)) {
+        return;
+      }
+      current = root->GetParent();
+    } while (current);
+  }
+
+  MOZ_ASSERT(aEvent->mMessage == eKeyDown || aEvent->mMessage == eMouseDown ||
+             aEvent->mMessage == ePointerDown || aEvent->mMessage == eTouchEnd);
+  doc->NotifyUserGestureActivation();
+}
+
+already_AddRefed<EventStateManager> EventStateManager::ESMFromContentOrThis(
+    nsIContent* aContent) {
+  if (aContent) {
+    PresShell* presShell = aContent->OwnerDoc()->GetPresShell();
+    if (presShell) {
+      nsPresContext* prescontext = presShell->GetPresContext();
+      if (prescontext) {
+        RefPtr<EventStateManager> esm = prescontext->EventStateManager();
+        if (esm) {
+          return esm.forget();
+        }
+      }
+    }
+  }
+
+  RefPtr<EventStateManager> esm = this;
+  return esm.forget();
+}
+
+void EventStateManager::HandleQueryContentEvent(
+    WidgetQueryContentEvent* aEvent) {
+  switch (aEvent->mMessage) {
+    case eQuerySelectedText:
+    case eQueryTextContent:
+    case eQueryCaretRect:
+    case eQueryTextRect:
+    case eQueryEditorRect:
+      if (!IsTargetCrossProcess(aEvent)) {
+        break;
+      }
+      // Will not be handled locally, remote the event
+      GetCrossProcessTarget()->HandleQueryContentEvent(*aEvent);
+      return;
+    // Following events have not been supported in e10s mode yet.
+    case eQueryContentState:
+    case eQuerySelectionAsTransferable:
+    case eQueryCharacterAtPoint:
+    case eQueryDOMWidgetHittest:
+    case eQueryTextRectArray:
+      break;
+    default:
+      return;
+  }
+
+  // If there is an IMEContentObserver, we need to handle QueryContentEvent
+  // with it.
+  if (mIMEContentObserver) {
+    RefPtr<IMEContentObserver> contentObserver = mIMEContentObserver;
+    contentObserver->HandleQueryContentEvent(aEvent);
+    return;
+  }
+
+  ContentEventHandler handler(mPresContext);
+  handler.HandleQueryContentEvent(aEvent);
+}
+
+static AccessKeyType GetAccessKeyTypeFor(nsISupports* aDocShell) {
+  nsCOMPtr<nsIDocShellTreeItem> treeItem(do_QueryInterface(aDocShell));
+  if (!treeItem) {
+    return AccessKeyType::eNone;
+  }
+
+  switch (treeItem->ItemType()) {
+    case nsIDocShellTreeItem::typeChrome:
+      return AccessKeyType::eChrome;
+    case nsIDocShellTreeItem::typeContent:
+      return AccessKeyType::eContent;
+    default:
+      return AccessKeyType::eNone;
+  }
+}
+
+static bool IsAccessKeyTarget(Element* aElement, nsAString& aKey) {
+  // Use GetAttr because we want Unicode case=insensitive matching
+  // XXXbz shouldn't this be case-sensitive, per spec?
+  nsString contentKey;
+  if (!aElement ||
+      !aElement->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, contentKey) ||
+      !contentKey.Equals(aKey, nsCaseInsensitiveStringComparator)) {
+    return false;
+  }
+
+  if (!aElement->IsXULElement()) {
+    return true;
+  }
+
+  // For XUL we do visibility checks.
+  nsIFrame* frame = aElement->GetPrimaryFrame();
+  if (!frame) {
+    return false;
+  }
+
+  if (frame->IsFocusable()) {
+    return true;
+  }
+
+  if (!frame->IsVisibleConsideringAncestors()) {
+    return false;
+  }
+
+  // XUL controls can be activated.
+  nsCOMPtr<nsIDOMXULControlElement> control = aElement->AsXULControl();
+  if (control) {
+    return true;
+  }
+
+  // XUL label elements are never focusable, so we need to check for them
+  // explicitly before giving up.
+  if (aElement->IsXULElement(nsGkAtoms::label)) {
+    return true;
+  }
+
+  return false;
+}
+
+bool EventStateManager::CheckIfEventMatchesAccessKey(
+    WidgetKeyboardEvent* aEvent, nsPresContext* aPresContext) {
+  AutoTArray<uint32_t, 10> accessCharCodes;
+  aEvent->GetAccessKeyCandidates(accessCharCodes);
+  return WalkESMTreeToHandleAccessKey(aEvent, aPresContext, accessCharCodes,
+                                      nullptr, eAccessKeyProcessingNormal,
+                                      false);
+}
+
+bool EventStateManager::LookForAccessKeyAndExecute(
+    nsTArray<uint32_t>& aAccessCharCodes, bool aIsTrustedEvent, bool aIsRepeat,
+    bool aExecute) {
+  int32_t count, start = -1;
+  if (Element* focusedElement = GetFocusedElement()) {
+    start = mAccessKeys.IndexOf(focusedElement);
+    if (start == -1 && focusedElement->IsInNativeAnonymousSubtree()) {
+      start = mAccessKeys.IndexOf(Element::FromNodeOrNull(
+          focusedElement->GetClosestNativeAnonymousSubtreeRootParent()));
+    }
+  }
+  RefPtr<Element> element;
+  int32_t length = mAccessKeys.Count();
+  for (uint32_t i = 0; i < aAccessCharCodes.Length(); ++i) {
+    uint32_t ch = aAccessCharCodes[i];
+    nsAutoString accessKey;
+    AppendUCS4ToUTF16(ch, accessKey);
+    for (count = 1; count <= length; ++count) {
+      // mAccessKeys always stores Element instances.
+      MOZ_DIAGNOSTIC_ASSERT(length == mAccessKeys.Count());
+      element = mAccessKeys[(start + count) % length];
+      if (IsAccessKeyTarget(element, accessKey)) {
+        if (!aExecute) {
+          return true;
+        }
+        Document* doc = element->OwnerDoc();
+        const bool shouldActivate = [&] {
+          if (!StaticPrefs::accessibility_accesskeycausesactivation()) {
+            return false;
+          }
+          if (aIsRepeat && nsContentUtils::IsChromeDoc(doc)) {
+            return false;
+          }
+
+          // XXXedgar, Bug 1700646, maybe we could use other data structure to
+          // make searching target with same accesskey easier, and current setup
+          // could not ensure we cycle the target with tree order.
+          int32_t j = 0;
+          while (++j < length) {
+            Element* el = mAccessKeys[(start + count + j) % length];
+            if (IsAccessKeyTarget(el, accessKey)) {
+              return false;
+            }
+          }
+          return true;
+        }();
+
+        // TODO(bug 1641171): This shouldn't be needed if we considered the
+        // accesskey combination properly.
+        if (aIsTrustedEvent) {
+          doc->NotifyUserGestureActivation();
+        }
+
+        auto result =
+            element->PerformAccesskey(shouldActivate, aIsTrustedEvent);
+        if (result.isOk()) {
+          if (result.unwrap() && aIsTrustedEvent) {
+            // If this is a child process, inform the parent that we want the
+            // focus, but pass false since we don't want to change the window
+            // order.
+            nsIDocShell* docShell = mPresContext->GetDocShell();
+            nsCOMPtr<nsIBrowserChild> child =
+                docShell ? docShell->GetBrowserChild() : nullptr;
+            if (child) {
+              child->SendRequestFocus(false, CallerType::System);
+            }
+          }
+          return true;
+        }
+      }
+    }
+  }
+  return false;
+}
+
+// static
+void EventStateManager::GetAccessKeyLabelPrefix(Element* aElement,
+                                                nsAString& aPrefix) {
+  aPrefix.Truncate();
+  nsAutoString separator, modifierText;
+  nsContentUtils::GetModifierSeparatorText(separator);
+
+  AccessKeyType accessKeyType =
+      GetAccessKeyTypeFor(aElement->OwnerDoc()->GetDocShell());
+  if (accessKeyType == AccessKeyType::eNone) {
+    return;
+  }
+  Modifiers modifiers = WidgetKeyboardEvent::AccessKeyModifiers(accessKeyType);
+  if (modifiers == MODIFIER_NONE) {
+    return;
+  }
+
+  if (modifiers & MODIFIER_CONTROL) {
+    nsContentUtils::GetControlText(modifierText);
+    aPrefix.Append(modifierText + separator);
+  }
+  if (modifiers & MODIFIER_META) {
+    nsContentUtils::GetMetaText(modifierText);
+    aPrefix.Append(modifierText + separator);
+  }
+  if (modifiers & MODIFIER_OS) {
+    nsContentUtils::GetOSText(modifierText);
+    aPrefix.Append(modifierText + separator);
+  }
+  if (modifiers & MODIFIER_ALT) {
+    nsContentUtils::GetAltText(modifierText);
+    aPrefix.Append(modifierText + separator);
+  }
+  if (modifiers & MODIFIER_SHIFT) {
+    nsContentUtils::GetShiftText(modifierText);
+    aPrefix.Append(modifierText + separator);
+  }
+}
+
+struct MOZ_STACK_CLASS AccessKeyInfo {
+  WidgetKeyboardEvent* event;
+  nsTArray<uint32_t>& charCodes;
+
+  AccessKeyInfo(WidgetKeyboardEvent* aEvent, nsTArray<uint32_t>& aCharCodes)
+      : event(aEvent), charCodes(aCharCodes) {}
+};
+
+bool EventStateManager::WalkESMTreeToHandleAccessKey(
+    WidgetKeyboardEvent* aEvent, nsPresContext* aPresContext,
+    nsTArray<uint32_t>& aAccessCharCodes, nsIDocShellTreeItem* aBubbledFrom,
+    ProcessingAccessKeyState aAccessKeyState, bool aExecute) {
+  EnsureDocument(mPresContext);
+  nsCOMPtr<nsIDocShell> docShell = aPresContext->GetDocShell();
+  if (NS_WARN_IF(!docShell) || NS_WARN_IF(!mDocument)) {
+    return false;
+  }
+  AccessKeyType accessKeyType = GetAccessKeyTypeFor(docShell);
+  if (accessKeyType == AccessKeyType::eNone) {
+    return false;
+  }
+  // Alt or other accesskey modifier is down, we may need to do an accesskey.
+  if (mAccessKeys.Count() > 0 &&
+      aEvent->ModifiersMatchWithAccessKey(accessKeyType)) {
+    // Someone registered an accesskey.  Find and activate it.
+    if (LookForAccessKeyAndExecute(aAccessCharCodes, aEvent->IsTrusted(),
+                                   aEvent->mIsRepeat, aExecute)) {
+      return true;
+    }
+  }
+
+  int32_t childCount;
+  docShell->GetInProcessChildCount(&childCount);
+  for (int32_t counter = 0; counter < childCount; counter++) {
+    // Not processing the child which bubbles up the handling
+    nsCOMPtr<nsIDocShellTreeItem> subShellItem;
+    docShell->GetInProcessChildAt(counter, getter_AddRefs(subShellItem));
+    if (aAccessKeyState == eAccessKeyProcessingUp &&
+        subShellItem == aBubbledFrom) {
+      continue;
+    }
+
+    nsCOMPtr<nsIDocShell> subDS = do_QueryInterface(subShellItem);
+    if (subDS && IsShellVisible(subDS)) {
+      // Guarantee subPresShell lifetime while we're handling access key
+      // since somebody may assume that it won't be deleted before the
+      // corresponding nsPresContext and EventStateManager.
+      RefPtr<PresShell> subPresShell = subDS->GetPresShell();
+
+      // Docshells need not have a presshell (eg. display:none
+      // iframes, docshells in transition between documents, etc).
+      if (!subPresShell) {
+        // Oh, well.  Just move on to the next child
+        continue;
+      }
+
+      RefPtr<nsPresContext> subPresContext = subPresShell->GetPresContext();
+
+      RefPtr<EventStateManager> esm =
+          static_cast<EventStateManager*>(subPresContext->EventStateManager());
+
+      if (esm && esm->WalkESMTreeToHandleAccessKey(
+                     aEvent, subPresContext, aAccessCharCodes, nullptr,
+                     eAccessKeyProcessingDown, aExecute)) {
+        return true;
+      }
+    }
+  }  // if end . checking all sub docshell ends here.
+
+  // bubble up the process to the parent docshell if necessary
+  if (eAccessKeyProcessingDown != aAccessKeyState) {
+    nsCOMPtr<nsIDocShellTreeItem> parentShellItem;
+    docShell->GetInProcessParent(getter_AddRefs(parentShellItem));
+    nsCOMPtr<nsIDocShell> parentDS = do_QueryInterface(parentShellItem);
+    if (parentDS) {
+      // Guarantee parentPresShell lifetime while we're handling access key
+      // since somebody may assume that it won't be deleted before the
+      // corresponding nsPresContext and EventStateManager.
+      RefPtr<PresShell> parentPresShell = parentDS->GetPresShell();
+      NS_ASSERTION(parentPresShell,
+                   "Our PresShell exists but the parent's does not?");
+
+      RefPtr<nsPresContext> parentPresContext =
+          parentPresShell->GetPresContext();
+      NS_ASSERTION(parentPresContext, "PresShell without PresContext");
+
+      RefPtr<EventStateManager> esm = static_cast<EventStateManager*>(
+          parentPresContext->EventStateManager());
+      if (esm && esm->WalkESMTreeToHandleAccessKey(
+                     aEvent, parentPresContext, aAccessCharCodes, docShell,
+                     eAccessKeyProcessingDown, aExecute)) {
+        return true;
+      }
+    }
+  }  // if end. bubble up process
+
+  // If the content access key modifier is pressed, try remote children
+  if (aExecute &&
+      aEvent->ModifiersMatchWithAccessKey(AccessKeyType::eContent) &&
+      mDocument && mDocument->GetWindow()) {
+    // If the focus is currently on a node with a BrowserParent, the key event
+    // should've gotten forwarded to the child process and HandleAccessKey
+    // called from there.
+    if (BrowserParent::GetFrom(GetFocusedElement())) {
+      // If access key may be only in remote contents, this method won't handle
+      // access key synchronously.  In this case, only reply event should reach
+      // here.
+      MOZ_ASSERT(aEvent->IsHandledInRemoteProcess() ||
+                 !aEvent->IsWaitingReplyFromRemoteProcess());
+    }
+    // If focus is somewhere else, then we need to check the remote children.
+    // However, if the event has already been handled in a remote process,
+    // then, focus is moved from the remote process after posting the event.
+    // In such case, we shouldn't retry to handle access keys in remote
+    // processes.
+    else if (!aEvent->IsHandledInRemoteProcess()) {
+      AccessKeyInfo accessKeyInfo(aEvent, aAccessCharCodes);
+      nsContentUtils::CallOnAllRemoteChildren(
+          mDocument->GetWindow(),
+          [&accessKeyInfo](BrowserParent* aBrowserParent) -> CallState {
+            // Only forward accesskeys for the active tab.
+            if (aBrowserParent->GetDocShellIsActive()) {
+              // Even if there is no target for the accesskey in this process,
+              // the event may match with a content accesskey.  If so, the
+              // keyboard event should be handled with reply event for
+              // preventing double action. (e.g., Alt+Shift+F on Windows may
+              // focus a content in remote and open "File" menu.)
+              accessKeyInfo.event->StopPropagation();
+              accessKeyInfo.event->MarkAsWaitingReplyFromRemoteProcess();
+              aBrowserParent->HandleAccessKey(*accessKeyInfo.event,
+                                              accessKeyInfo.charCodes);
+              return CallState::Stop;
+            }
+
+            return CallState::Continue;
+          });
+    }
+  }
+
+  return false;
+}  // end of HandleAccessKey
+
+static BrowserParent* GetBrowserParentAncestor(BrowserParent* aBrowserParent) {
+  MOZ_ASSERT(aBrowserParent);
+
+  BrowserBridgeParent* bbp = aBrowserParent->GetBrowserBridgeParent();
+  if (!bbp) {
+    return nullptr;
+  }
+
+  return bbp->Manager();
+}
+
+static void DispatchCrossProcessMouseExitEvents(WidgetMouseEvent* aMouseEvent,
+                                                BrowserParent* aRemoteTarget,
+                                                BrowserParent* aStopAncestor,
+                                                bool aIsReallyExit) {
+  MOZ_ASSERT(aMouseEvent);
+  MOZ_ASSERT(aRemoteTarget);
+  MOZ_ASSERT(aRemoteTarget != aStopAncestor);
+  MOZ_ASSERT_IF(aStopAncestor, nsContentUtils::GetCommonBrowserParentAncestor(
+                                   aRemoteTarget, aStopAncestor));
+
+  while (aRemoteTarget != aStopAncestor) {
+    UniquePtr<WidgetMouseEvent> mouseExitEvent =
+        CreateMouseOrPointerWidgetEvent(aMouseEvent, eMouseExitFromWidget,
+                                        aMouseEvent->mRelatedTarget);
+    mouseExitEvent->mExitFrom =
+        Some(aIsReallyExit ? WidgetMouseEvent::ePuppet
+                           : WidgetMouseEvent::ePuppetParentToPuppetChild);
+    aRemoteTarget->SendRealMouseEvent(*mouseExitEvent);
+
+    aRemoteTarget = GetBrowserParentAncestor(aRemoteTarget);
+  }
+}
+
+void EventStateManager::DispatchCrossProcessEvent(WidgetEvent* aEvent,
+                                                  BrowserParent* aRemoteTarget,
+                                                  nsEventStatus* aStatus) {
+  MOZ_ASSERT(aEvent);
+  MOZ_ASSERT(aRemoteTarget);
+  MOZ_ASSERT(aStatus);
+
+  BrowserParent* remote = aRemoteTarget;
+
+  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+  bool isContextMenuKey = mouseEvent && mouseEvent->IsContextMenuKeyEvent();
+  if (aEvent->mClass == eKeyboardEventClass || isContextMenuKey) {
+    // APZ attaches a LayersId to hit-testable events, for keyboard events,
+    // we use focus.
+    BrowserParent* preciseRemote = BrowserParent::GetFocused();
+    if (preciseRemote) {
+      remote = preciseRemote;
+    }
+    // else there is a race between layout and focus tracking,
+    // so fall back to delivering the event to the topmost child process.
+  } else if (aEvent->mLayersId.IsValid()) {
+    BrowserParent* preciseRemote =
+        BrowserParent::GetBrowserParentFromLayersId(aEvent->mLayersId);
+    if (preciseRemote) {
+      remote = preciseRemote;
+    }
+    // else there is a race between APZ and the LayersId to BrowserParent
+    // mapping, so fall back to delivering the event to the topmost child
+    // process.
+  }
+
+  switch (aEvent->mClass) {
+    case eMouseEventClass: {
+      BrowserParent* oldRemote = BrowserParent::GetLastMouseRemoteTarget();
+
+      // If this is a eMouseExitFromWidget event, need to redirect the event to
+      // the last remote and and notify all its ancestors about the exit, if
+      // any.
+      if (mouseEvent->mMessage == eMouseExitFromWidget) {
+        MOZ_ASSERT(mouseEvent->mExitFrom.value() == WidgetMouseEvent::ePuppet);
+        MOZ_ASSERT(mouseEvent->mReason == WidgetMouseEvent::eReal);
+        MOZ_ASSERT(!mouseEvent->mLayersId.IsValid());
+        MOZ_ASSERT(remote->GetBrowserHost());
+
+        if (oldRemote && oldRemote != remote) {
+          Unused << NS_WARN_IF(nsContentUtils::GetCommonBrowserParentAncestor(
+                                   remote, oldRemote) != remote);
+          remote = oldRemote;
+        }
+
+        DispatchCrossProcessMouseExitEvents(mouseEvent, remote, nullptr, true);
+        return;
+      }
+
+      if (BrowserParent* pointerLockedRemote =
+              PointerLockManager::GetLockedRemoteTarget()) {
+        remote = pointerLockedRemote;
+      } else if (BrowserParent* pointerCapturedRemote =
+                     PointerEventHandler::GetPointerCapturingRemoteTarget(
+                         mouseEvent->pointerId)) {
+        remote = pointerCapturedRemote;
+      } else if (BrowserParent* capturingRemote =
+                     PresShell::GetCapturingRemoteTarget()) {
+        remote = capturingRemote;
+      }
+
+      // If a mouse is over a remote target A, and then moves to
+      // remote target B, we'd deliver the event directly to remote target B
+      // after the moving, A would never get notified that the mouse left.
+      // So we generate a exit event to notify A after the move.
+      // XXXedgar, if the synthesized mouse events could deliver to the correct
+      // process directly (see
+      // https://bugzilla.mozilla.org/show_bug.cgi?id=1549355), we probably
+      // don't need to check mReason then.
+      if (mouseEvent->mReason == WidgetMouseEvent::eReal &&
+          remote != oldRemote) {
+        MOZ_ASSERT(mouseEvent->mMessage != eMouseExitFromWidget);
+        if (oldRemote) {
+          BrowserParent* commonAncestor =
+              nsContentUtils::GetCommonBrowserParentAncestor(remote, oldRemote);
+          if (commonAncestor == oldRemote) {
+            // Mouse moves to the inner OOP frame, it is not a really exit.
+            DispatchCrossProcessMouseExitEvents(
+                mouseEvent, GetBrowserParentAncestor(remote),
+                GetBrowserParentAncestor(commonAncestor), false);
+          } else if (commonAncestor == remote) {
+            // Mouse moves to the outer OOP frame, it is a really exit.
+            DispatchCrossProcessMouseExitEvents(mouseEvent, oldRemote,
+                                                commonAncestor, true);
+          } else {
+            // Mouse moves to OOP frame in other subtree, it is a really exit,
+            // need to notify all its ancestors before common ancestor about the
+            // exit.
+            DispatchCrossProcessMouseExitEvents(mouseEvent, oldRemote,
+                                                commonAncestor, true);
+            if (commonAncestor) {
+              UniquePtr<WidgetMouseEvent> mouseExitEvent =
+                  CreateMouseOrPointerWidgetEvent(mouseEvent,
+                                                  eMouseExitFromWidget,
+                                                  mouseEvent->mRelatedTarget);
+              mouseExitEvent->mExitFrom =
+                  Some(WidgetMouseEvent::ePuppetParentToPuppetChild);
+              commonAncestor->SendRealMouseEvent(*mouseExitEvent);
+            }
+          }
+        }
+
+        if (mouseEvent->mMessage != eMouseExitFromWidget &&
+            mouseEvent->mMessage != eMouseEnterIntoWidget) {
+          // This is to make cursor would be updated correctly.
+          remote->MouseEnterIntoWidget();
+        }
+      }
+
+      remote->SendRealMouseEvent(*mouseEvent);
+      return;
+    }
+    case eKeyboardEventClass: {
+      auto* keyboardEvent = aEvent->AsKeyboardEvent();
+      if (aEvent->mMessage == eKeyUp) {
+        HandleKeyUpInteraction(keyboardEvent);
+      }
+      remote->SendRealKeyEvent(*keyboardEvent);
+      return;
+    }
+    case eWheelEventClass: {
+      if (BrowserParent* pointerLockedRemote =
+              PointerLockManager::GetLockedRemoteTarget()) {
+        remote = pointerLockedRemote;
+      }
+      remote->SendMouseWheelEvent(*aEvent->AsWheelEvent());
+      return;
+    }
+    case eTouchEventClass: {
+      // Let the child process synthesize a mouse event if needed, and
+      // ensure we don't synthesize one in this process.
+      *aStatus = nsEventStatus_eConsumeNoDefault;
+      remote->SendRealTouchEvent(*aEvent->AsTouchEvent());
+      return;
+    }
+    case eDragEventClass: {
+      RefPtr<BrowserParent> browserParent = remote;
+      browserParent->Manager()->MaybeInvokeDragSession(browserParent);
+
+      nsCOMPtr<nsIDragSession> dragSession = nsContentUtils::GetDragSession();
+      uint32_t dropEffect = nsIDragService::DRAGDROP_ACTION_NONE;
+      uint32_t action = nsIDragService::DRAGDROP_ACTION_NONE;
+      nsCOMPtr<nsIPrincipal> principal;
+      nsCOMPtr<nsIContentSecurityPolicy> csp;
+
+      if (dragSession) {
+        dragSession->DragEventDispatchedToChildProcess();
+        dragSession->GetDragAction(&action);
+        dragSession->GetTriggeringPrincipal(getter_AddRefs(principal));
+        dragSession->GetCsp(getter_AddRefs(csp));
+        RefPtr<DataTransfer> initialDataTransfer =
+            dragSession->GetDataTransfer();
+        if (initialDataTransfer) {
+          dropEffect = initialDataTransfer->DropEffectInt();
+        }
+      }
+
+      browserParent->SendRealDragEvent(*aEvent->AsDragEvent(), action,
+                                       dropEffect, principal, csp);
+      return;
+    }
+    default: {
+      MOZ_CRASH("Attempt to send non-whitelisted event?");
+    }
+  }
+}
+
+bool EventStateManager::IsRemoteTarget(nsIContent* target) {
+  return BrowserParent::GetFrom(target) || BrowserBridgeChild::GetFrom(target);
+}
+
+bool EventStateManager::IsTopLevelRemoteTarget(nsIContent* target) {
+  return !!BrowserParent::GetFrom(target);
+}
+
+bool EventStateManager::HandleCrossProcessEvent(WidgetEvent* aEvent,
+                                                nsEventStatus* aStatus) {
+  if (!aEvent->CanBeSentToRemoteProcess()) {
+    return false;
+  }
+
+  MOZ_ASSERT(!aEvent->HasBeenPostedToRemoteProcess(),
+             "Why do we need to post same event to remote processes again?");
+
+  // Collect the remote event targets we're going to forward this
+  // event to.
+  //
+  // NB: the elements of |remoteTargets| must be unique, for correctness.
+  AutoTArray<RefPtr<BrowserParent>, 1> remoteTargets;
+  if (aEvent->mClass != eTouchEventClass || aEvent->mMessage == eTouchStart) {
+    // If this event only has one target, and it's remote, add it to
+    // the array.
+    nsIFrame* frame = aEvent->mMessage == eDragExit
+                          ? sLastDragOverFrame.GetFrame()
+                          : GetEventTarget();
+    nsIContent* target = frame ? frame->GetContent() : nullptr;
+    if (BrowserParent* remoteTarget = BrowserParent::GetFrom(target)) {
+      remoteTargets.AppendElement(remoteTarget);
+    }
+  } else {
+    // This is a touch event with possibly multiple touch points.
+    // Each touch point may have its own target.  So iterate through
+    // all of them and collect the unique set of targets for event
+    // forwarding.
+    //
+    // This loop is similar to the one used in
+    // PresShell::DispatchTouchEvent().
+    const WidgetTouchEvent::TouchArray& touches =
+        aEvent->AsTouchEvent()->mTouches;
+    for (uint32_t i = 0; i < touches.Length(); ++i) {
+      Touch* touch = touches[i];
+      // NB: the |mChanged| check is an optimization, subprocesses can
+      // compute this for themselves.  If the touch hasn't changed, we
+      // may be able to avoid forwarding the event entirely (which is
+      // not free).
+      if (!touch || !touch->mChanged) {
+        continue;
+      }
+      nsCOMPtr<EventTarget> targetPtr = touch->mTarget;
+      if (!targetPtr) {
+        continue;
+      }
+      nsCOMPtr<nsIContent> target = do_QueryInterface(targetPtr);
+      BrowserParent* remoteTarget = BrowserParent::GetFrom(target);
+      if (remoteTarget && !remoteTargets.Contains(remoteTarget)) {
+        remoteTargets.AppendElement(remoteTarget);
+      }
+    }
+  }
+
+  if (remoteTargets.Length() == 0) {
+    return false;
+  }
+
+  // Dispatch the event to the remote target.
+  for (uint32_t i = 0; i < remoteTargets.Length(); ++i) {
+    DispatchCrossProcessEvent(aEvent, remoteTargets[i], aStatus);
+  }
+  return aEvent->HasBeenPostedToRemoteProcess();
+}
+
+//
+// CreateClickHoldTimer
+//
+// Fire off a timer for determining if the user wants click-hold. This timer
+// is a one-shot that will be cancelled when the user moves enough to fire
+// a drag.
+//
+void EventStateManager::CreateClickHoldTimer(nsPresContext* inPresContext,
+                                             nsIFrame* inDownFrame,
+                                             WidgetGUIEvent* inMouseDownEvent) {
+  if (!inMouseDownEvent->IsTrusted() ||
+      IsTopLevelRemoteTarget(mGestureDownContent) ||
+      PointerLockManager::IsLocked()) {
+    return;
+  }
+
+  // just to be anal (er, safe)
+  if (mClickHoldTimer) {
+    mClickHoldTimer->Cancel();
+    mClickHoldTimer = nullptr;
+  }
+
+  // if content clicked on has a popup, don't even start the timer
+  // since we'll end up conflicting and both will show.
+  if (mGestureDownContent &&
+      nsContentUtils::HasNonEmptyAttr(mGestureDownContent, kNameSpaceID_None,
+                                      nsGkAtoms::popup)) {
+    return;
+  }
+
+  int32_t clickHoldDelay = StaticPrefs::ui_click_hold_context_menus_delay();
+  NS_NewTimerWithFuncCallback(
+      getter_AddRefs(mClickHoldTimer), sClickHoldCallback, this, clickHoldDelay,
+      nsITimer::TYPE_ONE_SHOT, "EventStateManager::CreateClickHoldTimer");
+}  // CreateClickHoldTimer
+
+//
+// KillClickHoldTimer
+//
+// Stop the timer that would show the context menu dead in its tracks
+//
+void EventStateManager::KillClickHoldTimer() {
+  if (mClickHoldTimer) {
+    mClickHoldTimer->Cancel();
+    mClickHoldTimer = nullptr;
+  }
+}
+
+//
+// sClickHoldCallback
+//
+// This fires after the mouse has been down for a certain length of time.
+//
+void EventStateManager::sClickHoldCallback(nsITimer* aTimer, void* aESM) {
+  RefPtr<EventStateManager> self = static_cast<EventStateManager*>(aESM);
+  if (self) {
+    self->FireContextClick();
+  }
+
+  // NOTE: |aTimer| and |self->mAutoHideTimer| are invalid after calling
+  // ClosePopup();
+
+}  // sAutoHideCallback
+
+//
+// FireContextClick
+//
+// If we're this far, our timer has fired, which means the mouse has been down
+// for a certain period of time and has not moved enough to generate a
+// dragGesture. We can be certain the user wants a context-click at this stage,
+// so generate a dom event and fire it in.
+//
+// After the event fires, check if PreventDefault() has been set on the event
+// which means that someone either ate the event or put up a context menu. This
+// is our cue to stop tracking the drag gesture. If we always did this,
+// draggable items w/out a context menu wouldn't be draggable after a certain
+// length of time, which is _not_ what we want.
+//
+void EventStateManager::FireContextClick() {
+  if (!mGestureDownContent || !mPresContext || PointerLockManager::IsLocked()) {
+    return;
+  }
+
+#ifdef XP_MACOSX
+  // Hack to ensure that we don't show a context menu when the user
+  // let go of the mouse after a long cpu-hogging operation prevented
+  // us from handling any OS events. See bug 117589.
+  if (!CGEventSourceButtonState(kCGEventSourceStateCombinedSessionState,
+                                kCGMouseButtonLeft))
+    return;
+#endif
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+
+  // Dispatch to the DOM. We have to fake out the ESM and tell it that the
+  // current target frame is actually where the mouseDown occurred, otherwise it
+  // will use the frame the mouse is currently over which may or may not be
+  // the same. (Note: saari and I have decided that we don't have to reset
+  // |mCurrentTarget| when we're through because no one else is doing anything
+  // more with this event and it will get reset on the very next event to the
+  // correct frame).
+  mCurrentTarget = mPresContext->GetPrimaryFrameFor(mGestureDownContent);
+  // make sure the widget sticks around
+  nsCOMPtr<nsIWidget> targetWidget;
+  if (mCurrentTarget && (targetWidget = mCurrentTarget->GetNearestWidget())) {
+    NS_ASSERTION(
+        mPresContext == mCurrentTarget->PresContext(),
+        "a prescontext returned a primary frame that didn't belong to it?");
+
+    // before dispatching, check that we're not on something that
+    // doesn't get a context menu
+    bool allowedToDispatch = true;
+
+    if (mGestureDownContent->IsAnyOfXULElements(nsGkAtoms::scrollbar,
+                                                nsGkAtoms::scrollbarbutton,
+                                                nsGkAtoms::button)) {
+      allowedToDispatch = false;
+    } else if (mGestureDownContent->IsXULElement(nsGkAtoms::toolbarbutton)) {
+      // a <toolbarbutton> that has the container attribute set
+      // will already have its own dropdown.
+      if (nsContentUtils::HasNonEmptyAttr(
+              mGestureDownContent, kNameSpaceID_None, nsGkAtoms::container)) {
+        allowedToDispatch = false;
+      } else {
+        // If the toolbar button has an open menu, don't attempt to open
+        // a second menu
+        if (mGestureDownContent->IsElement() &&
+            mGestureDownContent->AsElement()->AttrValueIs(
+                kNameSpaceID_None, nsGkAtoms::open, nsGkAtoms::_true,
+                eCaseMatters)) {
+          allowedToDispatch = false;
+        }
+      }
+    } else if (mGestureDownContent->IsHTMLElement()) {
+      nsCOMPtr<nsIFormControl> formCtrl(do_QueryInterface(mGestureDownContent));
+
+      if (formCtrl) {
+        allowedToDispatch =
+            formCtrl->IsTextControl(/*aExcludePassword*/ false) ||
+            formCtrl->ControlType() == FormControlType::InputFile;
+      } else if (mGestureDownContent->IsAnyOfHTMLElements(
+                     nsGkAtoms::embed, nsGkAtoms::object, nsGkAtoms::label)) {
+        allowedToDispatch = false;
+      }
+    }
+
+    if (allowedToDispatch) {
+      // init the event while mCurrentTarget is still good
+      WidgetMouseEvent event(true, eContextMenu, targetWidget,
+                             WidgetMouseEvent::eReal);
+      event.mClickCount = 1;
+      FillInEventFromGestureDown(&event);
+
+      // stop selection tracking, we're in control now
+      if (mCurrentTarget) {
+        RefPtr<nsFrameSelection> frameSel = mCurrentTarget->GetFrameSelection();
+
+        if (frameSel && frameSel->GetDragState()) {
+          // note that this can cause selection changed events to fire if we're
+          // in a text field, which will null out mCurrentTarget
+          frameSel->SetDragState(false);
+        }
+      }
+
+      AutoHandlingUserInputStatePusher userInpStatePusher(true, &event);
+
+      // dispatch to DOM
+      RefPtr<nsIContent> gestureDownContent = mGestureDownContent;
+      RefPtr<nsPresContext> presContext = mPresContext;
+      EventDispatcher::Dispatch(gestureDownContent, presContext, &event,
+                                nullptr, &status);
+
+      // We don't need to dispatch to frame handling because no frames
+      // watch eContextMenu except for nsMenuFrame and that's only for
+      // dismissal. That's just as well since we don't really know
+      // which frame to send it to.
+    }
+  }
+
+  // now check if the event has been handled. If so, stop tracking a drag
+  if (status == nsEventStatus_eConsumeNoDefault) {
+    StopTrackingDragGesture(true);
+  }
+
+  KillClickHoldTimer();
+
+}  // FireContextClick
+
+//
+// BeginTrackingDragGesture
+//
+// Record that the mouse has gone down and that we should move to TRACKING state
+// of d&d gesture tracker.
+//
+// We also use this to track click-hold context menus. When the mouse goes down,
+// fire off a short timer. If the timer goes off and we have yet to fire the
+// drag gesture (ie, the mouse hasn't moved a certain distance), then we can
+// assume the user wants a click-hold, so fire a context-click event. We only
+// want to cancel the drag gesture if the context-click event is handled.
+//
+void EventStateManager::BeginTrackingDragGesture(nsPresContext* aPresContext,
+                                                 WidgetMouseEvent* inDownEvent,
+                                                 nsIFrame* inDownFrame) {
+  if (!inDownEvent->mWidget) {
+    return;
+  }
+
+  // Note that |inDownEvent| could be either a mouse down event or a
+  // synthesized mouse move event.
+  SetGestureDownPoint(inDownEvent);
+
+  if (inDownFrame) {
+    inDownFrame->GetContentForEvent(inDownEvent,
+                                    getter_AddRefs(mGestureDownContent));
+
+    mGestureDownFrameOwner = inDownFrame->GetContent();
+    if (!mGestureDownFrameOwner) {
+      mGestureDownFrameOwner = mGestureDownContent;
+    }
+  }
+  mGestureModifiers = inDownEvent->mModifiers;
+  mGestureDownButtons = inDownEvent->mButtons;
+
+  if (inDownEvent->mMessage != eMouseTouchDrag &&
+      StaticPrefs::ui_click_hold_context_menus()) {
+    // fire off a timer to track click-hold
+    CreateClickHoldTimer(aPresContext, inDownFrame, inDownEvent);
+  }
+}
+
+void EventStateManager::SetGestureDownPoint(WidgetGUIEvent* aEvent) {
+  mGestureDownPoint =
+      GetEventRefPoint(aEvent) + aEvent->mWidget->WidgetToScreenOffset();
+}
+
+LayoutDeviceIntPoint EventStateManager::GetEventRefPoint(
+    WidgetEvent* aEvent) const {
+  auto touchEvent = aEvent->AsTouchEvent();
+  return (touchEvent && !touchEvent->mTouches.IsEmpty())
+             ? aEvent->AsTouchEvent()->mTouches[0]->mRefPoint
+             : aEvent->mRefPoint;
+}
+
+void EventStateManager::BeginTrackingRemoteDragGesture(
+    nsIContent* aContent, RemoteDragStartData* aDragStartData) {
+  mGestureDownContent = aContent;
+  mGestureDownFrameOwner = aContent;
+  mGestureDownInTextControl =
+      aContent && aContent->IsInNativeAnonymousSubtree() &&
+      TextControlElement::FromNodeOrNull(
+          aContent->GetClosestNativeAnonymousSubtreeRootParent());
+  mGestureDownDragStartData = aDragStartData;
+}
+
+//
+// StopTrackingDragGesture
+//
+// Record that the mouse has gone back up so that we should leave the TRACKING
+// state of d&d gesture tracker and return to the START state.
+//
+void EventStateManager::StopTrackingDragGesture(bool aClearInChildProcesses) {
+  mGestureDownContent = nullptr;
+  mGestureDownFrameOwner = nullptr;
+  mGestureDownInTextControl = false;
+  mGestureDownDragStartData = nullptr;
+
+  // If a content process starts a drag but the mouse is released before the
+  // parent starts the actual drag, the content process will think a drag is
+  // still happening. Inform any child processes with active drags that the drag
+  // should be stopped.
+  if (aClearInChildProcesses) {
+    nsCOMPtr<nsIDragService> dragService =
+        do_GetService("@mozilla.org/widget/dragservice;1");
+    if (dragService) {
+      nsCOMPtr<nsIDragSession> dragSession;
+      dragService->GetCurrentSession(getter_AddRefs(dragSession));
+      if (!dragSession) {
+        // Only notify if there isn't a drag session active.
+        dragService->RemoveAllChildProcesses();
+      }
+    }
+  }
+}
+
+void EventStateManager::FillInEventFromGestureDown(WidgetMouseEvent* aEvent) {
+  NS_ASSERTION(aEvent->mWidget == mCurrentTarget->GetNearestWidget(),
+               "Incorrect widget in event");
+
+  // Set the coordinates in the new event to the coordinates of
+  // the old event, adjusted for the fact that the widget might be
+  // different
+  aEvent->mRefPoint =
+      mGestureDownPoint - aEvent->mWidget->WidgetToScreenOffset();
+  aEvent->mModifiers = mGestureModifiers;
+  aEvent->mButtons = mGestureDownButtons;
+}
+
+void EventStateManager::MaybeFirePointerCancel(WidgetInputEvent* aEvent) {
+  RefPtr<PresShell> presShell = mPresContext->GetPresShell();
+  AutoWeakFrame targetFrame = mCurrentTarget;
+
+  if (!presShell || !targetFrame) {
+    return;
+  }
+
+  nsCOMPtr<nsIContent> content;
+  targetFrame->GetContentForEvent(aEvent, getter_AddRefs(content));
+  if (!content) {
+    return;
+  }
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+
+  if (WidgetMouseEvent* aMouseEvent = aEvent->AsMouseEvent()) {
+    WidgetPointerEvent event(*aMouseEvent);
+    PointerEventHandler::InitPointerEventFromMouse(&event, aMouseEvent,
+                                                   ePointerCancel);
+
+    event.convertToPointer = false;
+    presShell->HandleEventWithTarget(&event, targetFrame, content, &status);
+  } else if (WidgetTouchEvent* aTouchEvent = aEvent->AsTouchEvent()) {
+    WidgetPointerEvent event(aTouchEvent->IsTrusted(), ePointerCancel,
+                             aTouchEvent->mWidget);
+
+    PointerEventHandler::InitPointerEventFromTouch(
+        event, *aTouchEvent, *aTouchEvent->mTouches[0], true);
+
+    event.convertToPointer = false;
+    presShell->HandleEventWithTarget(&event, targetFrame, content, &status);
+  } else {
+    MOZ_ASSERT(false);
+  }
+
+  // HandleEventWithTarget clears out mCurrentTarget, which may be used in the
+  // caller GenerateDragGesture. We have to restore mCurrentTarget.
+  mCurrentTarget = targetFrame;
+}
+
+bool EventStateManager::IsEventOutsideDragThreshold(
+    WidgetInputEvent* aEvent) const {
+  static int32_t sPixelThresholdX = 0;
+  static int32_t sPixelThresholdY = 0;
+
+  if (!sPixelThresholdX) {
+    sPixelThresholdX =
+        LookAndFeel::GetInt(LookAndFeel::IntID::DragThresholdX, 0);
+    sPixelThresholdY =
+        LookAndFeel::GetInt(LookAndFeel::IntID::DragThresholdY, 0);
+    if (sPixelThresholdX <= 0) {
+      sPixelThresholdX = 5;
+    }
+    if (sPixelThresholdY <= 0) {
+      sPixelThresholdY = 5;
+    }
+  }
+
+  LayoutDeviceIntPoint pt =
+      aEvent->mWidget->WidgetToScreenOffset() + GetEventRefPoint(aEvent);
+  LayoutDeviceIntPoint distance = pt - mGestureDownPoint;
+  return Abs(distance.x) > sPixelThresholdX ||
+         Abs(distance.y) > sPixelThresholdY;
+}
+
+//
+// GenerateDragGesture
+//
+// If we're in the TRACKING state of the d&d gesture tracker, check the current
+// position of the mouse in relation to the old one. If we've moved a sufficient
+// amount from the mouse down, then fire off a drag gesture event.
+void EventStateManager::GenerateDragGesture(nsPresContext* aPresContext,
+                                            WidgetInputEvent* aEvent) {
+  NS_ASSERTION(aPresContext, "This shouldn't happen.");
+  if (!IsTrackingDragGesture()) {
+    return;
+  }
+
+  AutoWeakFrame targetFrameBefore = mCurrentTarget;
+  auto autoRestore = MakeScopeExit([&] { mCurrentTarget = targetFrameBefore; });
+  mCurrentTarget = mGestureDownFrameOwner->GetPrimaryFrame();
+
+  if (!mCurrentTarget || !mCurrentTarget->GetNearestWidget()) {
+    StopTrackingDragGesture(true);
+    return;
+  }
+
+  // Check if selection is tracking drag gestures, if so
+  // don't interfere!
+  if (mCurrentTarget) {
+    RefPtr<nsFrameSelection> frameSel = mCurrentTarget->GetFrameSelection();
+    if (frameSel && frameSel->GetDragState()) {
+      StopTrackingDragGesture(true);
+      return;
+    }
+  }
+
+  // If non-native code is capturing the mouse don't start a drag.
+  if (PresShell::IsMouseCapturePreventingDrag()) {
+    StopTrackingDragGesture(true);
+    return;
+  }
+
+  if (!IsEventOutsideDragThreshold(aEvent)) {
+    // To keep the old behavior, flush layout even if we don't start dnd.
+    FlushLayout(aPresContext);
+    return;
+  }
+
+  if (StaticPrefs::ui_click_hold_context_menus()) {
+    // stop the click-hold before we fire off the drag gesture, in case
+    // it takes a long time
+    KillClickHoldTimer();
+  }
+
+  nsCOMPtr<nsIDocShell> docshell = aPresContext->GetDocShell();
+  if (!docshell) {
+    return;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> window = docshell->GetWindow();
+  if (!window) return;
+
+  RefPtr<DataTransfer> dataTransfer =
+      new DataTransfer(window, eDragStart, false, -1);
+  auto protectDataTransfer = MakeScopeExit([&] {
+    if (dataTransfer) {
+      dataTransfer->Disconnect();
+    }
+  });
+
+  RefPtr<Selection> selection;
+  RefPtr<RemoteDragStartData> remoteDragStartData;
+  nsCOMPtr<nsIContent> eventContent, targetContent;
+  nsCOMPtr<nsIPrincipal> principal;
+  nsCOMPtr<nsIContentSecurityPolicy> csp;
+  nsCOMPtr<nsICookieJarSettings> cookieJarSettings;
+  bool allowEmptyDataTransfer = false;
+  mCurrentTarget->GetContentForEvent(aEvent, getter_AddRefs(eventContent));
+  if (eventContent) {
+    // If the content is a text node in a password field, we shouldn't
+    // allow to drag its raw text.  Note that we've supported drag from
+    // password fields but dragging data was masked text.  So, it doesn't
+    // make sense anyway.
+    if (eventContent->IsText() && eventContent->HasFlag(NS_MAYBE_MASKED)) {
+      // However, it makes sense to allow to drag selected password text
+      // when copying selected password is allowed because users may want
+      // to use drag and drop rather than copy and paste when web apps
+      // request to input password twice for conforming new password but
+      // they used password generator.
+      TextEditor* textEditor =
+          nsContentUtils::GetTextEditorFromAnonymousNodeWithoutCreation(
+              eventContent);
+      if (!textEditor || !textEditor->IsCopyToClipboardAllowed()) {
+        StopTrackingDragGesture(true);
+        return;
+      }
+    }
+    DetermineDragTargetAndDefaultData(
+        window, eventContent, dataTransfer, &allowEmptyDataTransfer,
+        getter_AddRefs(selection), getter_AddRefs(remoteDragStartData),
+        getter_AddRefs(targetContent), getter_AddRefs(principal),
+        getter_AddRefs(csp), getter_AddRefs(cookieJarSettings));
+  }
+
+  // Stop tracking the drag gesture now. This should stop us from
+  // reentering GenerateDragGesture inside DOM event processing.
+  // Pass false to avoid clearing the child process state since a real
+  // drag should be starting.
+  StopTrackingDragGesture(false);
+
+  if (!targetContent) return;
+
+  // Use our targetContent, now that we've determined it, as the
+  // parent object of the DataTransfer.
+  nsCOMPtr<nsIContent> parentContent =
+      targetContent->FindFirstNonChromeOnlyAccessContent();
+  dataTransfer->SetParentObject(parentContent);
+
+  sLastDragOverFrame = nullptr;
+  nsCOMPtr<nsIWidget> widget = mCurrentTarget->GetNearestWidget();
+
+  // get the widget from the target frame
+  WidgetDragEvent startEvent(aEvent->IsTrusted(), eDragStart, widget);
+  startEvent.mFlags.mIsSynthesizedForTests =
+      aEvent->mFlags.mIsSynthesizedForTests;
+  FillInEventFromGestureDown(&startEvent);
+
+  startEvent.mDataTransfer = dataTransfer;
+  if (aEvent->AsMouseEvent()) {
+    startEvent.mInputSource = aEvent->AsMouseEvent()->mInputSource;
+  } else if (aEvent->AsTouchEvent()) {
+    startEvent.mInputSource = MouseEvent_Binding::MOZ_SOURCE_TOUCH;
+  } else {
+    MOZ_ASSERT(false);
+  }
+
+  // Dispatch to the DOM. By setting mCurrentTarget we are faking
+  // out the ESM and telling it that the current target frame is
+  // actually where the mouseDown occurred, otherwise it will use
+  // the frame the mouse is currently over which may or may not be
+  // the same.
+
+  // Hold onto old target content through the event and reset after.
+  nsCOMPtr<nsIContent> targetBeforeEvent = mCurrentTargetContent;
+
+  // Set the current target to the content for the mouse down
+  mCurrentTargetContent = targetContent;
+
+  // Dispatch the dragstart event to the DOM.
+  nsEventStatus status = nsEventStatus_eIgnore;
+  EventDispatcher::Dispatch(targetContent, aPresContext, &startEvent, nullptr,
+                            &status);
+
+  WidgetDragEvent* event = &startEvent;
+
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  // Emit observer event to allow addons to modify the DataTransfer
+  // object.
+  if (observerService) {
+    observerService->NotifyObservers(dataTransfer, "on-datatransfer-available",
+                                     nullptr);
+  }
+
+  if (status != nsEventStatus_eConsumeNoDefault) {
+    bool dragStarted = DoDefaultDragStart(aPresContext, event, dataTransfer,
+                                          allowEmptyDataTransfer, targetContent,
+                                          selection, remoteDragStartData,
+                                          principal, csp, cookieJarSettings);
+    if (dragStarted) {
+      sActiveESM = nullptr;
+      MaybeFirePointerCancel(aEvent);
+      aEvent->StopPropagation();
+    }
+  }
+
+  // Reset mCurretTargetContent to what it was
+  mCurrentTargetContent = targetBeforeEvent;
+
+  // Now flush all pending notifications, for better responsiveness
+  // while dragging.
+  FlushLayout(aPresContext);
+}  // GenerateDragGesture
+
+void EventStateManager::DetermineDragTargetAndDefaultData(
+    nsPIDOMWindowOuter* aWindow, nsIContent* aSelectionTarget,
+    DataTransfer* aDataTransfer, bool* aAllowEmptyDataTransfer,
+    Selection** aSelection, RemoteDragStartData** aRemoteDragStartData,
+    nsIContent** aTargetNode, nsIPrincipal** aPrincipal,
+    nsIContentSecurityPolicy** aCsp,
+    nsICookieJarSettings** aCookieJarSettings) {
+  *aTargetNode = nullptr;
+  *aAllowEmptyDataTransfer = false;
+  nsCOMPtr<nsIContent> dragDataNode;
+
+  nsIContent* editingElement = aSelectionTarget->IsEditable()
+                                   ? aSelectionTarget->GetEditingHost()
+                                   : nullptr;
+
+  // In chrome, only allow dragging inside editable areas.
+  bool isChromeContext = !aWindow->GetBrowsingContext()->IsContent();
+  if (isChromeContext && !editingElement) {
+    if (mGestureDownDragStartData) {
+      // A child process started a drag so use any data it assigned for the dnd
+      // session.
+      mGestureDownDragStartData->AddInitialDnDDataTo(aDataTransfer, aPrincipal,
+                                                     aCsp, aCookieJarSettings);
+      mGestureDownDragStartData.forget(aRemoteDragStartData);
+      *aAllowEmptyDataTransfer = true;
+    }
+  } else {
+    mGestureDownDragStartData = nullptr;
+
+    // GetDragData determines if a selection, link or image in the content
+    // should be dragged, and places the data associated with the drag in the
+    // data transfer.
+    // mGestureDownContent is the node where the mousedown event for the drag
+    // occurred, and aSelectionTarget is the node to use when a selection is
+    // used
+    bool canDrag;
+    bool wasAlt = (mGestureModifiers & MODIFIER_ALT) != 0;
+    nsresult rv = nsContentAreaDragDrop::GetDragData(
+        aWindow, mGestureDownContent, aSelectionTarget, wasAlt, aDataTransfer,
+        &canDrag, aSelection, getter_AddRefs(dragDataNode), aPrincipal, aCsp,
+        aCookieJarSettings);
+    if (NS_FAILED(rv) || !canDrag) {
+      return;
+    }
+  }
+
+  // if GetDragData returned a node, use that as the node being dragged.
+  // Otherwise, if a selection is being dragged, use the node within the
+  // selection that was dragged. Otherwise, just use the mousedown target.
+  nsIContent* dragContent = mGestureDownContent;
+  if (dragDataNode)
+    dragContent = dragDataNode;
+  else if (*aSelection)
+    dragContent = aSelectionTarget;
+
+  nsIContent* originalDragContent = dragContent;
+
+  // If a selection isn't being dragged, look for an ancestor with the
+  // draggable property set. If one is found, use that as the target of the
+  // drag instead of the node that was clicked on. If a draggable node wasn't
+  // found, just use the clicked node.
+  if (!*aSelection) {
+    while (dragContent) {
+      if (auto htmlElement = nsGenericHTMLElement::FromNode(dragContent)) {
+        if (htmlElement->Draggable()) {
+          // We let draggable elements to trigger dnd even if there is no data
+          // in the DataTransfer.
+          *aAllowEmptyDataTransfer = true;
+          break;
+        }
+      } else {
+        if (dragContent->IsXULElement()) {
+          // All XUL elements are draggable, so if a XUL element is
+          // encountered, stop looking for draggable nodes and just use the
+          // original clicked node instead.
+          // XXXndeakin
+          // In the future, we will want to improve this so that XUL has a
+          // better way to specify whether something is draggable than just
+          // on/off.
+          dragContent = mGestureDownContent;
+          break;
+        }
+        // otherwise, it's not an HTML or XUL element, so just keep looking
+      }
+      dragContent = dragContent->GetFlattenedTreeParent();
+    }
+  }
+
+  // if no node in the hierarchy was found to drag, but the GetDragData method
+  // returned a node, use that returned node. Otherwise, nothing is draggable.
+  if (!dragContent && dragDataNode) dragContent = dragDataNode;
+
+  if (dragContent) {
+    // if an ancestor node was used instead, clear the drag data
+    // XXXndeakin rework this a bit. Find a way to just not call GetDragData if
+    // we don't need to.
+    if (dragContent != originalDragContent) aDataTransfer->ClearAll();
+    *aTargetNode = dragContent;
+    NS_ADDREF(*aTargetNode);
+  }
+}
+
+bool EventStateManager::DoDefaultDragStart(
+    nsPresContext* aPresContext, WidgetDragEvent* aDragEvent,
+    DataTransfer* aDataTransfer, bool aAllowEmptyDataTransfer,
+    nsIContent* aDragTarget, Selection* aSelection,
+    RemoteDragStartData* aDragStartData, nsIPrincipal* aPrincipal,
+    nsIContentSecurityPolicy* aCsp, nsICookieJarSettings* aCookieJarSettings) {
+  nsCOMPtr<nsIDragService> dragService =
+      do_GetService("@mozilla.org/widget/dragservice;1");
+  if (!dragService) return false;
+
+  // Default handling for the dragstart event.
+  //
+  // First, check if a drag session already exists. This means that the drag
+  // service was called directly within a draggesture handler. In this case,
+  // don't do anything more, as it is assumed that the handler is managing
+  // drag and drop manually. Make sure to return true to indicate that a drag
+  // began.  However, if we're handling drag session for synthesized events,
+  // we need to initialize some information of the session.  Therefore, we
+  // need to keep going for synthesized case.
+  nsCOMPtr<nsIDragSession> dragSession;
+  dragService->GetCurrentSession(getter_AddRefs(dragSession));
+  if (dragSession && !dragSession->IsSynthesizedForTests()) {
+    return true;
+  }
+
+  // No drag session is currently active, so check if a handler added
+  // any items to be dragged. If not, there isn't anything to drag.
+  uint32_t count = 0;
+  if (aDataTransfer) {
+    count = aDataTransfer->MozItemCount();
+  }
+  if (!aAllowEmptyDataTransfer && !count) {
+    return false;
+  }
+
+  // Get the target being dragged, which may not be the same as the
+  // target of the mouse event. If one wasn't set in the
+  // aDataTransfer during the event handler, just use the original
+  // target instead.
+  nsCOMPtr<nsIContent> dragTarget = aDataTransfer->GetDragTarget();
+  if (!dragTarget) {
+    dragTarget = aDragTarget;
+    if (!dragTarget) {
+      return false;
+    }
+  }
+
+  // check which drag effect should initially be used. If the effect was not
+  // set, just use all actions, otherwise Windows won't allow a drop.
+  uint32_t action = aDataTransfer->EffectAllowedInt();
+  if (action == nsIDragService::DRAGDROP_ACTION_UNINITIALIZED) {
+    action = nsIDragService::DRAGDROP_ACTION_COPY |
+             nsIDragService::DRAGDROP_ACTION_MOVE |
+             nsIDragService::DRAGDROP_ACTION_LINK;
+  }
+
+  // get any custom drag image that was set
+  int32_t imageX, imageY;
+  RefPtr<Element> dragImage = aDataTransfer->GetDragImage(&imageX, &imageY);
+
+  nsCOMPtr<nsIArray> transArray = aDataTransfer->GetTransferables(dragTarget);
+  if (!transArray) {
+    return false;
+  }
+
+  RefPtr<DataTransfer> dataTransfer;
+  if (!dragSession) {
+    // After this function returns, the DataTransfer will be cleared so it
+    // appears empty to content. We need to pass a DataTransfer into the Drag
+    // Session, so we need to make a copy.
+    aDataTransfer->Clone(aDragTarget, eDrop, aDataTransfer->MozUserCancelled(),
+                         false, getter_AddRefs(dataTransfer));
+
+    // Copy over the drop effect, as Clone doesn't copy it for us.
+    dataTransfer->SetDropEffectInt(aDataTransfer->DropEffectInt());
+  } else {
+    MOZ_ASSERT(dragSession->IsSynthesizedForTests());
+    MOZ_ASSERT(aDragEvent->mFlags.mIsSynthesizedForTests);
+    // If we're initializing synthesized drag session, we should use given
+    // DataTransfer as is because it'll be used with following drag events
+    // in any tests, therefore it should be set to nsIDragSession.dataTransfer
+    // because it and DragEvent.dataTransfer should be same instance.
+    dataTransfer = aDataTransfer;
+  }
+
+  // XXXndeakin don't really want to create a new drag DOM event
+  // here, but we need something to pass to the InvokeDragSession
+  // methods.
+  RefPtr<DragEvent> event =
+      NS_NewDOMDragEvent(dragTarget, aPresContext, aDragEvent);
+
+  // Use InvokeDragSessionWithSelection if a selection is being dragged,
+  // such that the image can be generated from the selected text. However,
+  // use InvokeDragSessionWithImage if a custom image was set or something
+  // other than a selection is being dragged.
+  if (!dragImage && aSelection) {
+    dragService->InvokeDragSessionWithSelection(aSelection, aPrincipal, aCsp,
+                                                aCookieJarSettings, transArray,
+                                                action, event, dataTransfer);
+  } else if (aDragStartData) {
+    MOZ_ASSERT(XRE_IsParentProcess());
+    dragService->InvokeDragSessionWithRemoteImage(
+        dragTarget, aPrincipal, aCsp, aCookieJarSettings, transArray, action,
+        aDragStartData, event, dataTransfer);
+  } else {
+    dragService->InvokeDragSessionWithImage(
+        dragTarget, aPrincipal, aCsp, aCookieJarSettings, transArray, action,
+        dragImage, imageX, imageY, event, dataTransfer);
+  }
+
+  return true;
+}
+
+void EventStateManager::ChangeZoom(bool aIncrease) {
+  // Send the zoom change to the top level browser so it will be handled by the
+  // front end in the same way as other zoom actions.
+  nsIDocShell* docShell = mDocument->GetDocShell();
+  if (!docShell) {
+    return;
+  }
+
+  BrowsingContext* bc = docShell->GetBrowsingContext();
+  if (!bc) {
+    return;
+  }
+
+  if (XRE_IsParentProcess()) {
+    bc->Canonical()->DispatchWheelZoomChange(aIncrease);
+  } else if (BrowserChild* child = BrowserChild::GetFrom(docShell)) {
+    child->SendWheelZoomChange(aIncrease);
+  }
+}
+
+void EventStateManager::DoScrollHistory(int32_t direction) {
+  nsCOMPtr<nsISupports> pcContainer(mPresContext->GetContainerWeak());
+  if (pcContainer) {
+    nsCOMPtr<nsIWebNavigation> webNav(do_QueryInterface(pcContainer));
+    if (webNav) {
+      // positive direction to go back one step, nonpositive to go forward
+      // This is doing user-initiated history traversal, hence we want
+      // to require that history entries we navigate to have user interaction.
+      if (direction > 0)
+        webNav->GoBack(StaticPrefs::browser_navigation_requireUserInteraction(),
+                       true);
+      else
+        webNav->GoForward(
+            StaticPrefs::browser_navigation_requireUserInteraction(), true);
+    }
+  }
+}
+
+void EventStateManager::DoScrollZoom(nsIFrame* aTargetFrame,
+                                     int32_t adjustment) {
+  // Exclude content in chrome docshells.
+  nsIContent* content = aTargetFrame->GetContent();
+  if (content && !nsContentUtils::IsInChromeDocshell(content->OwnerDoc())) {
+    // Positive adjustment to decrease zoom, negative to increase
+    const bool increase = adjustment <= 0;
+    EnsureDocument(mPresContext);
+    ChangeZoom(increase);
+  }
+}
+
+static nsIFrame* GetParentFrameToScroll(nsIFrame* aFrame) {
+  if (!aFrame) return nullptr;
+
+  if (aFrame->StyleDisplay()->mPosition == StylePositionProperty::Fixed &&
+      nsLayoutUtils::IsReallyFixedPos(aFrame))
+    return aFrame->PresContext()->GetPresShell()->GetRootScrollFrame();
+
+  return aFrame->GetParent();
+}
+
+void EventStateManager::DispatchLegacyMouseScrollEvents(
+    nsIFrame* aTargetFrame, WidgetWheelEvent* aEvent, nsEventStatus* aStatus) {
+  MOZ_ASSERT(aEvent);
+  MOZ_ASSERT(aStatus);
+
+  if (!aTargetFrame || *aStatus == nsEventStatus_eConsumeNoDefault) {
+    return;
+  }
+
+  // Ignore mouse wheel transaction for computing legacy mouse wheel
+  // events' delta value.
+  // DOM event's delta vales are computed from CSS pixels.
+  auto scrollAmountInCSSPixels =
+      CSSIntSize::FromAppUnitsRounded(aEvent->mScrollAmount);
+
+  // XXX We don't deal with fractional amount in legacy event, though the
+  //     default action handler (DoScrollText()) deals with it.
+  //     If we implemented such strict computation, we would need additional
+  //     accumulated delta values. It would made the code more complicated.
+  //     And also it would computes different delta values from older version.
+  //     It doesn't make sense to implement such code for legacy events and
+  //     rare cases.
+  int32_t scrollDeltaX, scrollDeltaY, pixelDeltaX, pixelDeltaY;
+  switch (aEvent->mDeltaMode) {
+    case WheelEvent_Binding::DOM_DELTA_PAGE:
+      scrollDeltaX = !aEvent->mLineOrPageDeltaX
+                         ? 0
+                         : (aEvent->mLineOrPageDeltaX > 0
+                                ? UIEvent_Binding::SCROLL_PAGE_DOWN
+                                : UIEvent_Binding::SCROLL_PAGE_UP);
+      scrollDeltaY = !aEvent->mLineOrPageDeltaY
+                         ? 0
+                         : (aEvent->mLineOrPageDeltaY > 0
+                                ? UIEvent_Binding::SCROLL_PAGE_DOWN
+                                : UIEvent_Binding::SCROLL_PAGE_UP);
+      pixelDeltaX = RoundDown(aEvent->mDeltaX * scrollAmountInCSSPixels.width);
+      pixelDeltaY = RoundDown(aEvent->mDeltaY * scrollAmountInCSSPixels.height);
+      break;
+
+    case WheelEvent_Binding::DOM_DELTA_LINE:
+      scrollDeltaX = aEvent->mLineOrPageDeltaX;
+      scrollDeltaY = aEvent->mLineOrPageDeltaY;
+      pixelDeltaX = RoundDown(aEvent->mDeltaX * scrollAmountInCSSPixels.width);
+      pixelDeltaY = RoundDown(aEvent->mDeltaY * scrollAmountInCSSPixels.height);
+      break;
+
+    case WheelEvent_Binding::DOM_DELTA_PIXEL:
+      scrollDeltaX = aEvent->mLineOrPageDeltaX;
+      scrollDeltaY = aEvent->mLineOrPageDeltaY;
+      pixelDeltaX = RoundDown(aEvent->mDeltaX);
+      pixelDeltaY = RoundDown(aEvent->mDeltaY);
+      break;
+
+    default:
+      MOZ_CRASH("Invalid deltaMode value comes");
+  }
+
+  // Send the legacy events in following order:
+  // 1. Vertical scroll
+  // 2. Vertical pixel scroll (even if #1 isn't consumed)
+  // 3. Horizontal scroll (even if #1 and/or #2 are consumed)
+  // 4. Horizontal pixel scroll (even if #3 isn't consumed)
+
+  AutoWeakFrame targetFrame(aTargetFrame);
+
+  MOZ_ASSERT(*aStatus != nsEventStatus_eConsumeNoDefault &&
+                 !aEvent->DefaultPrevented(),
+             "If you make legacy events dispatched for default prevented wheel "
+             "event, you need to initialize stateX and stateY");
+  EventState stateX, stateY;
+  if (scrollDeltaY) {
+    SendLineScrollEvent(aTargetFrame, aEvent, stateY, scrollDeltaY,
+                        DELTA_DIRECTION_Y);
+    if (!targetFrame.IsAlive()) {
+      *aStatus = nsEventStatus_eConsumeNoDefault;
+      return;
+    }
+  }
+
+  if (pixelDeltaY) {
+    SendPixelScrollEvent(aTargetFrame, aEvent, stateY, pixelDeltaY,
+                         DELTA_DIRECTION_Y);
+    if (!targetFrame.IsAlive()) {
+      *aStatus = nsEventStatus_eConsumeNoDefault;
+      return;
+    }
+  }
+
+  if (scrollDeltaX) {
+    SendLineScrollEvent(aTargetFrame, aEvent, stateX, scrollDeltaX,
+                        DELTA_DIRECTION_X);
+    if (!targetFrame.IsAlive()) {
+      *aStatus = nsEventStatus_eConsumeNoDefault;
+      return;
+    }
+  }
+
+  if (pixelDeltaX) {
+    SendPixelScrollEvent(aTargetFrame, aEvent, stateX, pixelDeltaX,
+                         DELTA_DIRECTION_X);
+    if (!targetFrame.IsAlive()) {
+      *aStatus = nsEventStatus_eConsumeNoDefault;
+      return;
+    }
+  }
+
+  if (stateY.mDefaultPrevented) {
+    *aStatus = nsEventStatus_eConsumeNoDefault;
+    aEvent->PreventDefault(!stateY.mDefaultPreventedByContent);
+  }
+
+  if (stateX.mDefaultPrevented) {
+    *aStatus = nsEventStatus_eConsumeNoDefault;
+    aEvent->PreventDefault(!stateX.mDefaultPreventedByContent);
+  }
+}
+
+void EventStateManager::SendLineScrollEvent(nsIFrame* aTargetFrame,
+                                            WidgetWheelEvent* aEvent,
+                                            EventState& aState, int32_t aDelta,
+                                            DeltaDirection aDeltaDirection) {
+  nsCOMPtr<nsIContent> targetContent = aTargetFrame->GetContent();
+  if (!targetContent) {
+    targetContent = GetFocusedElement();
+    if (!targetContent) {
+      return;
+    }
+  }
+
+  while (targetContent->IsText()) {
+    targetContent = targetContent->GetFlattenedTreeParent();
+  }
+
+  WidgetMouseScrollEvent event(aEvent->IsTrusted(),
+                               eLegacyMouseLineOrPageScroll, aEvent->mWidget);
+  event.mFlags.mDefaultPrevented = aState.mDefaultPrevented;
+  event.mFlags.mDefaultPreventedByContent = aState.mDefaultPreventedByContent;
+  event.mRefPoint = aEvent->mRefPoint;
+  event.mTimeStamp = aEvent->mTimeStamp;
+  event.mModifiers = aEvent->mModifiers;
+  event.mButtons = aEvent->mButtons;
+  event.mIsHorizontal = (aDeltaDirection == DELTA_DIRECTION_X);
+  event.mDelta = aDelta;
+  event.mInputSource = aEvent->mInputSource;
+
+  RefPtr<nsPresContext> presContext = aTargetFrame->PresContext();
+  nsEventStatus status = nsEventStatus_eIgnore;
+  EventDispatcher::Dispatch(targetContent, presContext, &event, nullptr,
+                            &status);
+  aState.mDefaultPrevented =
+      event.DefaultPrevented() || status == nsEventStatus_eConsumeNoDefault;
+  aState.mDefaultPreventedByContent = event.DefaultPreventedByContent();
+}
+
+void EventStateManager::SendPixelScrollEvent(nsIFrame* aTargetFrame,
+                                             WidgetWheelEvent* aEvent,
+                                             EventState& aState,
+                                             int32_t aPixelDelta,
+                                             DeltaDirection aDeltaDirection) {
+  nsCOMPtr<nsIContent> targetContent = aTargetFrame->GetContent();
+  if (!targetContent) {
+    targetContent = GetFocusedElement();
+    if (!targetContent) {
+      return;
+    }
+  }
+
+  while (targetContent->IsText()) {
+    targetContent = targetContent->GetFlattenedTreeParent();
+  }
+
+  WidgetMouseScrollEvent event(aEvent->IsTrusted(), eLegacyMousePixelScroll,
+                               aEvent->mWidget);
+  event.mFlags.mDefaultPrevented = aState.mDefaultPrevented;
+  event.mFlags.mDefaultPreventedByContent = aState.mDefaultPreventedByContent;
+  event.mRefPoint = aEvent->mRefPoint;
+  event.mTimeStamp = aEvent->mTimeStamp;
+  event.mModifiers = aEvent->mModifiers;
+  event.mButtons = aEvent->mButtons;
+  event.mIsHorizontal = (aDeltaDirection == DELTA_DIRECTION_X);
+  event.mDelta = aPixelDelta;
+  event.mInputSource = aEvent->mInputSource;
+
+  RefPtr<nsPresContext> presContext = aTargetFrame->PresContext();
+  nsEventStatus status = nsEventStatus_eIgnore;
+  EventDispatcher::Dispatch(targetContent, presContext, &event, nullptr,
+                            &status);
+  aState.mDefaultPrevented =
+      event.DefaultPrevented() || status == nsEventStatus_eConsumeNoDefault;
+  aState.mDefaultPreventedByContent = event.DefaultPreventedByContent();
+}
+
+nsIFrame* EventStateManager::ComputeScrollTargetAndMayAdjustWheelEvent(
+    nsIFrame* aTargetFrame, WidgetWheelEvent* aEvent,
+    ComputeScrollTargetOptions aOptions) {
+  return ComputeScrollTargetAndMayAdjustWheelEvent(
+      aTargetFrame, aEvent->mDeltaX, aEvent->mDeltaY, aEvent, aOptions);
+}
+
+// Overload ComputeScrollTargetAndMayAdjustWheelEvent method to allow passing
+// "test" dx and dy when looking for which scrollbarmediators to activate when
+// two finger down on trackpad and before any actual motion
+nsIFrame* EventStateManager::ComputeScrollTargetAndMayAdjustWheelEvent(
+    nsIFrame* aTargetFrame, double aDirectionX, double aDirectionY,
+    WidgetWheelEvent* aEvent, ComputeScrollTargetOptions aOptions) {
+  bool isAutoDir = false;
+  bool honoursRoot = false;
+  if (MAY_BE_ADJUSTED_BY_AUTO_DIR & aOptions) {
+    // If the scroll is respected as auto-dir, aDirection* should always be
+    // equivalent to the event's delta vlaues(Currently, there are only one case
+    // where aDirection*s have different values from the widget wheel event's
+    // original delta values and the only case isn't auto-dir, see
+    // ScrollbarsForWheel::TemporarilyActivateAllPossibleScrollTargets).
+    MOZ_ASSERT(aDirectionX == aEvent->mDeltaX &&
+               aDirectionY == aEvent->mDeltaY);
+
+    WheelDeltaAdjustmentStrategy strategy =
+        GetWheelDeltaAdjustmentStrategy(*aEvent);
+    switch (strategy) {
+      case WheelDeltaAdjustmentStrategy::eAutoDir:
+        isAutoDir = true;
+        honoursRoot = false;
+        break;
+      case WheelDeltaAdjustmentStrategy::eAutoDirWithRootHonour:
+        isAutoDir = true;
+        honoursRoot = true;
+        break;
+      default:
+        break;
+    }
+  }
+
+  if (aOptions & PREFER_MOUSE_WHEEL_TRANSACTION) {
+    // If the user recently scrolled with the mousewheel, then they probably
+    // want to scroll the same view as before instead of the view under the
+    // cursor.  WheelTransaction tracks the frame currently being
+    // scrolled with the mousewheel. We consider the transaction ended when the
+    // mouse moves more than "mousewheel.transaction.ignoremovedelay"
+    // milliseconds after the last scroll operation, or any time the mouse moves
+    // out of the frame, or when more than "mousewheel.transaction.timeout"
+    // milliseconds have passed after the last operation, even if the mouse
+    // hasn't moved.
+    nsIFrame* lastScrollFrame = WheelTransaction::GetTargetFrame();
+    if (lastScrollFrame) {
+      nsIScrollableFrame* scrollableFrame =
+          lastScrollFrame->GetScrollTargetFrame();
+      if (scrollableFrame) {
+        nsIFrame* frameToScroll = do_QueryFrame(scrollableFrame);
+        MOZ_ASSERT(frameToScroll);
+        if (isAutoDir) {
+          ESMAutoDirWheelDeltaAdjuster adjuster(*aEvent, *lastScrollFrame,
+                                                honoursRoot);
+          // Note that calling this function will not always cause the delta to
+          // be adjusted, it only adjusts the delta when it should, because
+          // Adjust() internally calls ShouldBeAdjusted() before making
+          // adjustment.
+          adjuster.Adjust();
+        }
+        return frameToScroll;
+      }
+    }
+  }
+
+  // If the event doesn't cause scroll actually, we cannot find scroll target
+  // because we check if the event can cause scroll actually on each found
+  // scrollable frame.
+  if (!aDirectionX && !aDirectionY) {
+    return nullptr;
+  }
+
+  bool checkIfScrollableX;
+  bool checkIfScrollableY;
+  if (isAutoDir) {
+    // Always check the frame's scrollability in both the two directions for an
+    // auto-dir scroll. That is, for an auto-dir scroll,
+    // PREFER_ACTUAL_SCROLLABLE_TARGET_ALONG_X_AXIS and
+    // PREFER_ACTUAL_SCROLLABLE_TARGET_ALONG_Y_AXIS should be ignored.
+    checkIfScrollableX = true;
+    checkIfScrollableY = true;
+  } else {
+    checkIfScrollableX =
+        aDirectionX &&
+        (aOptions & PREFER_ACTUAL_SCROLLABLE_TARGET_ALONG_X_AXIS);
+    checkIfScrollableY =
+        aDirectionY &&
+        (aOptions & PREFER_ACTUAL_SCROLLABLE_TARGET_ALONG_Y_AXIS);
+  }
+
+  nsIFrame* scrollFrame = !(aOptions & START_FROM_PARENT)
+                              ? aTargetFrame
+                              : GetParentFrameToScroll(aTargetFrame);
+  for (; scrollFrame; scrollFrame = GetParentFrameToScroll(scrollFrame)) {
+    // Check whether the frame wants to provide us with a scrollable view.
+    nsIScrollableFrame* scrollableFrame = scrollFrame->GetScrollTargetFrame();
+    if (!scrollableFrame) {
+      nsMenuPopupFrame* menuPopupFrame = do_QueryFrame(scrollFrame);
+      if (menuPopupFrame) {
+        return nullptr;
+      }
+      continue;
+    }
+
+    nsIFrame* frameToScroll = do_QueryFrame(scrollableFrame);
+    MOZ_ASSERT(frameToScroll);
+
+    if (!checkIfScrollableX && !checkIfScrollableY) {
+      return frameToScroll;
+    }
+
+    // If the frame disregards the direction the user is trying to scroll, then
+    // it should just bubbles the scroll event up to its parental scroll frame
+
+    Maybe<layers::ScrollDirection> disregardedDirection =
+        WheelHandlingUtils::GetDisregardedWheelScrollDirection(scrollFrame);
+    if (disregardedDirection) {
+      switch (disregardedDirection.ref()) {
+        case layers::ScrollDirection::eHorizontal:
+          if (checkIfScrollableX) {
+            continue;
+          }
+          break;
+        case layers::ScrollDirection::eVertical:
+          if (checkIfScrollableY) {
+            continue;
+          }
+          break;
+      }
+    }
+
+    layers::ScrollDirections directions =
+        scrollableFrame->GetAvailableScrollingDirectionsForUserInputEvents();
+    if ((!(directions.contains(layers::ScrollDirection::eVertical)) &&
+         !(directions.contains(layers::ScrollDirection::eHorizontal))) ||
+        (checkIfScrollableY && !checkIfScrollableX &&
+         !(directions.contains(layers::ScrollDirection::eVertical))) ||
+        (checkIfScrollableX && !checkIfScrollableY &&
+         !(directions.contains(layers::ScrollDirection::eHorizontal)))) {
+      continue;
+    }
+
+    // Computes whether the currently checked frame is scrollable by this wheel
+    // event.
+    bool canScroll = false;
+    if (isAutoDir) {
+      ESMAutoDirWheelDeltaAdjuster adjuster(*aEvent, *scrollFrame, honoursRoot);
+      if (adjuster.ShouldBeAdjusted()) {
+        adjuster.Adjust();
+        canScroll = true;
+      } else if (WheelHandlingUtils::CanScrollOn(scrollableFrame, aDirectionX,
+                                                 aDirectionY)) {
+        canScroll = true;
+      }
+    } else if (WheelHandlingUtils::CanScrollOn(scrollableFrame, aDirectionX,
+                                               aDirectionY)) {
+      canScroll = true;
+    }
+
+    if (canScroll) {
+      return frameToScroll;
+    }
+
+    // Where we are at is the block ending in a for loop.
+    // The current frame has been checked to be unscrollable by this wheel
+    // event, continue the loop to check its parent, if any.
+  }
+
+  nsIFrame* newFrame = nsLayoutUtils::GetCrossDocParentFrameInProcess(
+      aTargetFrame->PresShell()->GetRootFrame());
+  aOptions =
+      static_cast<ComputeScrollTargetOptions>(aOptions & ~START_FROM_PARENT);
+  if (!newFrame) {
+    return nullptr;
+  }
+  return ComputeScrollTargetAndMayAdjustWheelEvent(newFrame, aEvent, aOptions);
+}
+
+nsSize EventStateManager::GetScrollAmount(
+    nsPresContext* aPresContext, WidgetWheelEvent* aEvent,
+    nsIScrollableFrame* aScrollableFrame) {
+  MOZ_ASSERT(aPresContext);
+  MOZ_ASSERT(aEvent);
+
+  const bool isPage = aEvent->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PAGE;
+  if (!aScrollableFrame) {
+    // If there is no scrollable frame, we should use root, see below.
+    aScrollableFrame =
+        aPresContext->PresShell()->GetRootScrollFrameAsScrollable();
+  }
+
+  if (aScrollableFrame) {
+    return isPage ? aScrollableFrame->GetPageScrollAmount()
+                  : aScrollableFrame->GetLineScrollAmount();
+  }
+
+  // If there is no scrollable frame and page scrolling, use viewport size.
+  if (isPage) {
+    return aPresContext->GetVisibleArea().Size();
+  }
+
+  // Otherwise use root frame's font metrics.
+  //
+  // FIXME(emilio): Should this use the root element's style frame? The root
+  // frame will always have the initial font. Then again it should never matter
+  // for content, we should always have a root scrollable frame in html
+  // documents.
+  nsIFrame* rootFrame = aPresContext->PresShell()->GetRootFrame();
+  if (!rootFrame) {
+    return nsSize(0, 0);
+  }
+  RefPtr<nsFontMetrics> fm =
+      nsLayoutUtils::GetInflatedFontMetricsForFrame(rootFrame);
+  NS_ENSURE_TRUE(fm, nsSize(0, 0));
+  return nsSize(fm->AveCharWidth(), fm->MaxHeight());
+}
+
+void EventStateManager::DoScrollText(nsIScrollableFrame* aScrollableFrame,
+                                     WidgetWheelEvent* aEvent) {
+  MOZ_ASSERT(aScrollableFrame);
+  MOZ_ASSERT(aEvent);
+
+  nsIFrame* scrollFrame = do_QueryFrame(aScrollableFrame);
+  MOZ_ASSERT(scrollFrame);
+
+  AutoWeakFrame scrollFrameWeak(scrollFrame);
+  if (!WheelTransaction::WillHandleDefaultAction(aEvent, scrollFrameWeak)) {
+    return;
+  }
+
+  // Default action's actual scroll amount should be computed from device
+  // pixels.
+  nsPresContext* pc = scrollFrame->PresContext();
+  nsSize scrollAmount = GetScrollAmount(pc, aEvent, aScrollableFrame);
+  nsIntSize scrollAmountInDevPixels(
+      pc->AppUnitsToDevPixels(scrollAmount.width),
+      pc->AppUnitsToDevPixels(scrollAmount.height));
+  nsIntPoint actualDevPixelScrollAmount =
+      DeltaAccumulator::GetInstance()->ComputeScrollAmountForDefaultAction(
+          aEvent, scrollAmountInDevPixels);
+
+  // Don't scroll around the axis whose overflow style is hidden.
+  ScrollStyles overflowStyle = aScrollableFrame->GetScrollStyles();
+  if (overflowStyle.mHorizontal == StyleOverflow::Hidden) {
+    actualDevPixelScrollAmount.x = 0;
+  }
+  if (overflowStyle.mVertical == StyleOverflow::Hidden) {
+    actualDevPixelScrollAmount.y = 0;
+  }
+
+  ScrollSnapFlags snapFlags = ScrollSnapFlags::Disabled;
+  mozilla::ScrollOrigin origin = mozilla::ScrollOrigin::NotSpecified;
+  switch (aEvent->mDeltaMode) {
+    case WheelEvent_Binding::DOM_DELTA_LINE:
+      origin = mozilla::ScrollOrigin::MouseWheel;
+      snapFlags = ScrollSnapFlags::IntendedDirection;
+      break;
+    case WheelEvent_Binding::DOM_DELTA_PAGE:
+      origin = mozilla::ScrollOrigin::Pages;
+      snapFlags = ScrollSnapFlags::IntendedDirection |
+                  ScrollSnapFlags::IntendedEndPosition;
+      break;
+    case WheelEvent_Binding::DOM_DELTA_PIXEL:
+      origin = mozilla::ScrollOrigin::Pixels;
+      break;
+    default:
+      MOZ_CRASH("Invalid deltaMode value comes");
+  }
+
+  // We shouldn't scroll more one page at once except when over one page scroll
+  // is allowed for the event.
+  nsSize pageSize = aScrollableFrame->GetPageScrollAmount();
+  nsIntSize devPixelPageSize(pc->AppUnitsToDevPixels(pageSize.width),
+                             pc->AppUnitsToDevPixels(pageSize.height));
+  if (!WheelPrefs::GetInstance()->IsOverOnePageScrollAllowedX(aEvent) &&
+      DeprecatedAbs(actualDevPixelScrollAmount.x.value) >
+          devPixelPageSize.width) {
+    actualDevPixelScrollAmount.x = (actualDevPixelScrollAmount.x >= 0)
+                                       ? devPixelPageSize.width
+                                       : -devPixelPageSize.width;
+  }
+
+  if (!WheelPrefs::GetInstance()->IsOverOnePageScrollAllowedY(aEvent) &&
+      DeprecatedAbs(actualDevPixelScrollAmount.y.value) >
+          devPixelPageSize.height) {
+    actualDevPixelScrollAmount.y = (actualDevPixelScrollAmount.y >= 0)
+                                       ? devPixelPageSize.height
+                                       : -devPixelPageSize.height;
+  }
+
+  bool isDeltaModePixel =
+      (aEvent->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL);
+
+  ScrollMode mode;
+  switch (aEvent->mScrollType) {
+    case WidgetWheelEvent::SCROLL_DEFAULT:
+      if (isDeltaModePixel) {
+        mode = ScrollMode::Normal;
+      } else if (aEvent->mFlags.mHandledByAPZ) {
+        mode = ScrollMode::SmoothMsd;
+      } else {
+        mode = ScrollMode::Smooth;
+      }
+      break;
+    case WidgetWheelEvent::SCROLL_SYNCHRONOUSLY:
+      mode = ScrollMode::Instant;
+      break;
+    case WidgetWheelEvent::SCROLL_ASYNCHRONOUSLY:
+      mode = ScrollMode::Normal;
+      break;
+    case WidgetWheelEvent::SCROLL_SMOOTHLY:
+      mode = ScrollMode::Smooth;
+      break;
+    default:
+      MOZ_CRASH("Invalid mScrollType value comes");
+  }
+
+  nsIScrollableFrame::ScrollMomentum momentum =
+      aEvent->mIsMomentum ? nsIScrollableFrame::SYNTHESIZED_MOMENTUM_EVENT
+                          : nsIScrollableFrame::NOT_MOMENTUM;
+
+  nsIntPoint overflow;
+  aScrollableFrame->ScrollBy(actualDevPixelScrollAmount,
+                             ScrollUnit::DEVICE_PIXELS, mode, &overflow, origin,
+                             momentum, snapFlags);
+
+  if (!scrollFrameWeak.IsAlive()) {
+    // If the scroll causes changing the layout, we can think that the event
+    // has been completely consumed by the content.  Then, users probably don't
+    // want additional action.
+    aEvent->mOverflowDeltaX = aEvent->mOverflowDeltaY = 0;
+  } else if (isDeltaModePixel) {
+    aEvent->mOverflowDeltaX = overflow.x;
+    aEvent->mOverflowDeltaY = overflow.y;
+  } else {
+    aEvent->mOverflowDeltaX =
+        static_cast<double>(overflow.x) / scrollAmountInDevPixels.width;
+    aEvent->mOverflowDeltaY =
+        static_cast<double>(overflow.y) / scrollAmountInDevPixels.height;
+  }
+
+  // If CSS overflow properties caused not to scroll, the overflowDelta* values
+  // should be same as delta* values since they may be used as gesture event by
+  // widget.  However, if there is another scrollable element in the ancestor
+  // along the axis, probably users don't want the operation to cause
+  // additional action such as moving history.  In such case, overflowDelta
+  // values should stay zero.
+  if (scrollFrameWeak.IsAlive()) {
+    if (aEvent->mDeltaX && overflowStyle.mHorizontal == StyleOverflow::Hidden &&
+        !ComputeScrollTargetAndMayAdjustWheelEvent(
+            scrollFrame, aEvent,
+            COMPUTE_SCROLLABLE_ANCESTOR_ALONG_X_AXIS_WITH_AUTO_DIR)) {
+      aEvent->mOverflowDeltaX = aEvent->mDeltaX;
+    }
+    if (aEvent->mDeltaY && overflowStyle.mVertical == StyleOverflow::Hidden &&
+        !ComputeScrollTargetAndMayAdjustWheelEvent(
+            scrollFrame, aEvent,
+            COMPUTE_SCROLLABLE_ANCESTOR_ALONG_Y_AXIS_WITH_AUTO_DIR)) {
+      aEvent->mOverflowDeltaY = aEvent->mDeltaY;
+    }
+  }
+
+  NS_ASSERTION(
+      aEvent->mOverflowDeltaX == 0 ||
+          (aEvent->mOverflowDeltaX > 0) == (aEvent->mDeltaX > 0),
+      "The sign of mOverflowDeltaX is different from the scroll direction");
+  NS_ASSERTION(
+      aEvent->mOverflowDeltaY == 0 ||
+          (aEvent->mOverflowDeltaY > 0) == (aEvent->mDeltaY > 0),
+      "The sign of mOverflowDeltaY is different from the scroll direction");
+
+  WheelPrefs::GetInstance()->CancelApplyingUserPrefsFromOverflowDelta(aEvent);
+}
+
+void EventStateManager::DecideGestureEvent(WidgetGestureNotifyEvent* aEvent,
+                                           nsIFrame* targetFrame) {
+  NS_ASSERTION(aEvent->mMessage == eGestureNotify,
+               "DecideGestureEvent called with a non-gesture event");
+
+  /* Check the ancestor tree to decide if any frame is willing* to receive
+   * a MozPixelScroll event. If that's the case, the current touch gesture
+   * will be used as a pan gesture; otherwise it will be a regular
+   * mousedown/mousemove/click event.
+   *
+   * *willing: determine if it makes sense to pan the element using scroll
+   * events:
+   *  - For web content: if there are any visible scrollbars on the touch point
+   *  - For XUL: if it's an scrollable element that can currently scroll in some
+   *    direction.
+   *
+   * Note: we'll have to one-off various cases to ensure a good usable behavior
+   */
+  WidgetGestureNotifyEvent::PanDirection panDirection =
+      WidgetGestureNotifyEvent::ePanNone;
+  bool displayPanFeedback = false;
+  for (nsIFrame* current = targetFrame; current;
+       current = nsLayoutUtils::GetCrossDocParentFrame(current)) {
+    // e10s - mark remote content as pannable. This is a work around since
+    // we don't have access to remote frame scroll info here. Apz data may
+    // assist is solving this.
+    if (current && IsTopLevelRemoteTarget(current->GetContent())) {
+      panDirection = WidgetGestureNotifyEvent::ePanBoth;
+      // We don't know when we reach bounds, so just disable feedback for now.
+      displayPanFeedback = false;
+      break;
+    }
+
+    LayoutFrameType currentFrameType = current->Type();
+
+    // Scrollbars should always be draggable
+    if (currentFrameType == LayoutFrameType::Scrollbar) {
+      panDirection = WidgetGestureNotifyEvent::ePanNone;
+      break;
+    }
+
+    // Special check for trees
+    nsTreeBodyFrame* treeFrame = do_QueryFrame(current);
+    if (treeFrame) {
+      if (treeFrame->GetHorizontalOverflow()) {
+        panDirection = WidgetGestureNotifyEvent::ePanHorizontal;
+      }
+      if (treeFrame->GetVerticalOverflow()) {
+        panDirection = WidgetGestureNotifyEvent::ePanVertical;
+      }
+      break;
+    }
+
+    if (nsIScrollableFrame* scrollableFrame = do_QueryFrame(current)) {
+      if (current->IsFrameOfType(nsIFrame::eXULBox)) {
+        displayPanFeedback = true;
+
+        nsRect scrollRange = scrollableFrame->GetScrollRange();
+        bool canScrollHorizontally = scrollRange.width > 0;
+
+        // Vertical panning has priority over horizontal panning, so
+        // when vertical movement is possible we can just finish the loop.
+        if (scrollRange.height > 0) {
+          panDirection = WidgetGestureNotifyEvent::ePanVertical;
+          break;
+        }
+
+        if (canScrollHorizontally) {
+          panDirection = WidgetGestureNotifyEvent::ePanHorizontal;
+          displayPanFeedback = false;
+        }
+      } else {  // Not a XUL box
+        layers::ScrollDirections scrollbarVisibility =
+            scrollableFrame->GetScrollbarVisibility();
+
+        // Check if we have visible scrollbars
+        if (scrollbarVisibility.contains(layers::ScrollDirection::eVertical)) {
+          panDirection = WidgetGestureNotifyEvent::ePanVertical;
+          displayPanFeedback = true;
+          break;
+        }
+
+        if (scrollbarVisibility.contains(
+                layers::ScrollDirection::eHorizontal)) {
+          panDirection = WidgetGestureNotifyEvent::ePanHorizontal;
+          displayPanFeedback = true;
+        }
+      }
+    }  // scrollableFrame
+  }    // ancestor chain
+  aEvent->mDisplayPanFeedback = displayPanFeedback;
+  aEvent->mPanDirection = panDirection;
+}
+
+#ifdef XP_MACOSX
+static nsINode* GetCrossDocParentNode(nsINode* aChild) {
+  MOZ_ASSERT(aChild, "The child is null!");
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  nsINode* parent = aChild->GetParentNode();
+  if (parent && parent->IsContent() && aChild->IsContent()) {
+    parent = aChild->AsContent()->GetFlattenedTreeParent();
+  }
+
+  if (parent || !aChild->IsDocument()) {
+    return parent;
+  }
+
+  return aChild->AsDocument()->GetEmbedderElement();
+}
+
+static bool NodeAllowsClickThrough(nsINode* aNode) {
+  while (aNode) {
+    if (aNode->IsXULElement(nsGkAtoms::browser)) {
+      return false;
+    }
+    if (aNode->IsXULElement()) {
+      mozilla::dom::Element* element = aNode->AsElement();
+      static Element::AttrValuesArray strings[] = {nsGkAtoms::always,
+                                                   nsGkAtoms::never, nullptr};
+      switch (element->FindAttrValueIn(
+          kNameSpaceID_None, nsGkAtoms::clickthrough, strings, eCaseMatters)) {
+        case 0:
+          return true;
+        case 1:
+          return false;
+      }
+    }
+    aNode = GetCrossDocParentNode(aNode);
+  }
+  return true;
+}
+#endif
+
+void EventStateManager::PostHandleKeyboardEvent(
+    WidgetKeyboardEvent* aKeyboardEvent, nsIFrame* aTargetFrame,
+    nsEventStatus& aStatus) {
+  if (aStatus == nsEventStatus_eConsumeNoDefault) {
+    return;
+  }
+
+  RefPtr<nsPresContext> presContext = mPresContext;
+
+  if (!aKeyboardEvent->HasBeenPostedToRemoteProcess()) {
+    if (aKeyboardEvent->IsWaitingReplyFromRemoteProcess()) {
+      RefPtr<BrowserParent> remote =
+          aTargetFrame ? BrowserParent::GetFrom(aTargetFrame->GetContent())
+                       : nullptr;
+      if (remote) {
+        // remote is null-checked above in order to let pre-existing event
+        // targeting code's chrome vs. content decision override in case of
+        // disagreement in order not to disrupt non-Fission e10s mode in case
+        // there are still bugs in the Fission-mode code. That is, if remote
+        // is nullptr, the pre-existing event targeting code has deemed this
+        // event to belong to chrome rather than content.
+        BrowserParent* preciseRemote = BrowserParent::GetFocused();
+        if (preciseRemote) {
+          remote = preciseRemote;
+        }
+        // else there was a race between layout and focus tracking
+      }
+      if (remote && !remote->IsReadyToHandleInputEvents()) {
+        // We need to dispatch the event to the browser element again if we were
+        // waiting for the key reply but the event wasn't sent to the content
+        // process due to the remote browser wasn't ready.
+        WidgetKeyboardEvent keyEvent(*aKeyboardEvent);
+        aKeyboardEvent->MarkAsHandledInRemoteProcess();
+        RefPtr<Element> ownerElement = remote->GetOwnerElement();
+        EventDispatcher::Dispatch(ownerElement, presContext, &keyEvent);
+        if (keyEvent.DefaultPrevented()) {
+          aKeyboardEvent->PreventDefault(!keyEvent.DefaultPreventedByContent());
+          aStatus = nsEventStatus_eConsumeNoDefault;
+          return;
+        }
+      }
+    }
+    // The widget expects a reply for every keyboard event. If the event wasn't
+    // dispatched to a content process (non-e10s or no content process
+    // running), we need to short-circuit here. Otherwise, we need to wait for
+    // the content process to handle the event.
+    if (aKeyboardEvent->mWidget) {
+      aKeyboardEvent->mWidget->PostHandleKeyEvent(aKeyboardEvent);
+    }
+    if (aKeyboardEvent->DefaultPrevented()) {
+      aStatus = nsEventStatus_eConsumeNoDefault;
+      return;
+    }
+  }
+
+  // XXX Currently, our automated tests don't support mKeyNameIndex.
+  //     Therefore, we still need to handle this with keyCode.
+  switch (aKeyboardEvent->mKeyCode) {
+    case NS_VK_TAB:
+    case NS_VK_F6:
+      // This is to prevent keyboard scrolling while alt modifier in use.
+      if (!aKeyboardEvent->IsAlt()) {
+        aStatus = nsEventStatus_eConsumeNoDefault;
+
+        // Handling the tab event after it was sent to content is bad,
+        // because to the FocusManager the remote-browser looks like one
+        // element, so we would just move the focus to the next element
+        // in chrome, instead of handling it in content.
+        if (aKeyboardEvent->HasBeenPostedToRemoteProcess()) {
+          break;
+        }
+
+        EnsureDocument(presContext);
+        nsFocusManager* fm = nsFocusManager::GetFocusManager();
+        if (fm && mDocument) {
+          // Shift focus forward or back depending on shift key
+          bool isDocMove = aKeyboardEvent->IsControl() ||
+                           aKeyboardEvent->mKeyCode == NS_VK_F6;
+          uint32_t dir =
+              aKeyboardEvent->IsShift()
+                  ? (isDocMove ? static_cast<uint32_t>(
+                                     nsIFocusManager::MOVEFOCUS_BACKWARDDOC)
+                               : static_cast<uint32_t>(
+                                     nsIFocusManager::MOVEFOCUS_BACKWARD))
+                  : (isDocMove ? static_cast<uint32_t>(
+                                     nsIFocusManager::MOVEFOCUS_FORWARDDOC)
+                               : static_cast<uint32_t>(
+                                     nsIFocusManager::MOVEFOCUS_FORWARD));
+          RefPtr<Element> result;
+          fm->MoveFocus(mDocument->GetWindow(), nullptr, dir,
+                        nsIFocusManager::FLAG_BYKEY, getter_AddRefs(result));
+        }
+      }
+      return;
+    case 0:
+      // We handle keys with no specific keycode value below.
+      break;
+    default:
+      return;
+  }
+
+  switch (aKeyboardEvent->mKeyNameIndex) {
+    case KEY_NAME_INDEX_ZoomIn:
+    case KEY_NAME_INDEX_ZoomOut:
+      ChangeZoom(aKeyboardEvent->mKeyNameIndex == KEY_NAME_INDEX_ZoomIn);
+      aStatus = nsEventStatus_eConsumeNoDefault;
+      break;
+    default:
+      break;
+  }
+}
+
+nsresult EventStateManager::PostHandleEvent(nsPresContext* aPresContext,
+                                            WidgetEvent* aEvent,
+                                            nsIFrame* aTargetFrame,
+                                            nsEventStatus* aStatus,
+                                            nsIContent* aOverrideClickTarget) {
+  NS_ENSURE_ARG(aPresContext);
+  NS_ENSURE_ARG_POINTER(aStatus);
+
+  mCurrentTarget = aTargetFrame;
+  mCurrentTargetContent = nullptr;
+
+  HandleCrossProcessEvent(aEvent, aStatus);
+  // NOTE: the above call may have destroyed aTargetFrame, please use
+  // mCurrentTarget henceforth.  This is to avoid using it accidentally:
+  aTargetFrame = nullptr;
+
+  // Most of the events we handle below require a frame.
+  // Add special cases here.
+  if (!mCurrentTarget && aEvent->mMessage != eMouseUp &&
+      aEvent->mMessage != eMouseDown && aEvent->mMessage != eDragEnter &&
+      aEvent->mMessage != eDragOver && aEvent->mMessage != ePointerUp &&
+      aEvent->mMessage != ePointerCancel) {
+    return NS_OK;
+  }
+
+  // Keep the prescontext alive, we might need it after event dispatch
+  RefPtr<nsPresContext> presContext = aPresContext;
+  nsresult ret = NS_OK;
+
+  switch (aEvent->mMessage) {
+    case eMouseDown: {
+      WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
+      if (mouseEvent->mButton == MouseButton::ePrimary &&
+          !sNormalLMouseEventInProcess) {
+        // We got a mouseup event while a mousedown event was being processed.
+        // Make sure that the capturing content is cleared.
+        PresShell::ReleaseCapturingContent();
+        break;
+      }
+
+      // For remote content, capture the event in the parent process at the
+      // <xul:browser remote> element. This will ensure that subsequent
+      // mousemove/mouseup events will continue to be dispatched to this element
+      // and therefore forwarded to the child.
+      if (aEvent->HasBeenPostedToRemoteProcess() &&
+          !PresShell::GetCapturingContent()) {
+        if (nsIContent* content =
+                mCurrentTarget ? mCurrentTarget->GetContent() : nullptr) {
+          PresShell::SetCapturingContent(content, CaptureFlags::None, aEvent);
+        } else {
+          PresShell::ReleaseCapturingContent();
+        }
+      }
+
+      // If MouseEvent::PreventClickEvent() was called by chrome script,
+      // we need to forget the clicking content and click count for the
+      // following eMouseUp event.
+      if (mouseEvent->mClickEventPrevented) {
+        RefPtr<EventStateManager> esm =
+            ESMFromContentOrThis(aOverrideClickTarget);
+        switch (mouseEvent->mButton) {
+          case MouseButton::ePrimary:
+            esm->mLastLeftMouseDownContent = nullptr;
+            esm->mLClickCount = 0;
+            break;
+          case MouseButton::eSecondary:
+            esm->mLastMiddleMouseDownContent = nullptr;
+            esm->mMClickCount = 0;
+            break;
+          case MouseButton::eMiddle:
+            esm->mLastRightMouseDownContent = nullptr;
+            esm->mRClickCount = 0;
+            break;
+          default:
+            break;
+        }
+      }
+
+      nsCOMPtr<nsIContent> activeContent;
+      // When content calls PreventDefault on pointerdown, we also call
+      // PreventDefault on the subsequent mouse events to suppress default
+      // behaviors. Normally, aStatus should be nsEventStatus_eConsumeNoDefault
+      // when the event is DefaultPrevented but it's reset to
+      // nsEventStatus_eIgnore in EventStateManager::PreHandleEvent. So we also
+      // check if the event is DefaultPrevented.
+      if (nsEventStatus_eConsumeNoDefault != *aStatus &&
+          !aEvent->DefaultPrevented()) {
+        nsCOMPtr<nsIContent> newFocus;
+        bool suppressBlur = false;
+        if (mCurrentTarget) {
+          mCurrentTarget->GetContentForEvent(aEvent, getter_AddRefs(newFocus));
+          activeContent = mCurrentTarget->GetContent();
+
+          // In some cases, we do not want to even blur the current focused
+          // element. Those cases are:
+          // 1. -moz-user-focus CSS property is set to 'ignore';
+          // 2. XUL control element has the disabled property set to 'true'.
+          //
+          // We can't use nsIFrame::IsFocusable() because we want to blur when
+          // we click on a visibility: none element.
+          // We can't use nsIContent::IsFocusable() because we want to blur when
+          // we click on a non-focusable element like a <div>.
+          // We have to use |aEvent->mTarget| to not make sure we do not check
+          // an anonymous node of the targeted element.
+          suppressBlur =
+              mCurrentTarget->StyleUI()->UserFocus() == StyleUserFocus::Ignore;
+
+          if (!suppressBlur) {
+            if (Element* element =
+                    Element::FromEventTargetOrNull(aEvent->mTarget)) {
+              if (nsCOMPtr<nsIDOMXULControlElement> xulControl =
+                      element->AsXULControl()) {
+                bool disabled = false;
+                xulControl->GetDisabled(&disabled);
+                suppressBlur = disabled;
+              }
+            }
+          }
+        }
+
+        // When a root content which isn't editable but has an editable HTML
+        // <body> element is clicked, we should redirect the focus to the
+        // the <body> element.  E.g., when an user click bottom of the editor
+        // where is outside of the <body> element, the <body> should be focused
+        // and the user can edit immediately after that.
+        //
+        // NOTE: The newFocus isn't editable that also means it's not in
+        // designMode.  In designMode, all contents are not focusable.
+        if (newFocus && !newFocus->IsEditable()) {
+          Document* doc = newFocus->GetComposedDoc();
+          if (doc && newFocus == doc->GetRootElement()) {
+            nsIContent* bodyContent =
+                nsLayoutUtils::GetEditableRootContentByContentEditable(doc);
+            if (bodyContent && bodyContent->GetPrimaryFrame()) {
+              newFocus = bodyContent;
+            }
+          }
+        }
+
+        // When the mouse is pressed, the default action is to focus the
+        // target. Look for the nearest enclosing focusable frame.
+        //
+        // TODO: Probably this should be moved to Element::PostHandleEvent.
+        for (; newFocus; newFocus = newFocus->GetFlattenedTreeParent()) {
+          if (!newFocus->IsElement()) {
+            continue;
+          }
+
+          nsIFrame* frame = newFocus->GetPrimaryFrame();
+          if (!frame) {
+            continue;
+          }
+
+          // If the mousedown happened inside a popup, don't try to set focus on
+          // one of its containing elements
+          if (frame->IsMenuPopupFrame()) {
+            newFocus = nullptr;
+            break;
+          }
+
+          if (frame->IsFocusable(/* aWithMouse = */ true)) {
+            break;
+          }
+
+          if (ShadowRoot* root = newFocus->GetShadowRoot()) {
+            if (root->DelegatesFocus()) {
+              if (Element* firstFocusable =
+                      root->GetFocusDelegate(/* aWithMouse */ true)) {
+                newFocus = firstFocusable;
+                break;
+              }
+            }
+          }
+        }
+
+        MOZ_ASSERT_IF(newFocus, newFocus->IsElement());
+
+        if (RefPtr<nsFocusManager> fm = nsFocusManager::GetFocusManager()) {
+          // if something was found to focus, focus it. Otherwise, if the
+          // element that was clicked doesn't have -moz-user-focus: ignore,
+          // clear the existing focus. For -moz-user-focus: ignore, the focus
+          // is just left as is.
+          // Another effect of mouse clicking, handled in Selection, is that
+          // it should update the caret position to where the mouse was
+          // clicked. Because the focus is cleared when clicking on a
+          // non-focusable node, the next press of the tab key will cause
+          // focus to be shifted from the caret position instead of the root.
+          if (newFocus) {
+            // use the mouse flag and the noscroll flag so that the content
+            // doesn't unexpectedly scroll when clicking an element that is
+            // only half visible
+            uint32_t flags =
+                nsIFocusManager::FLAG_BYMOUSE | nsIFocusManager::FLAG_NOSCROLL;
+            // If this was a touch-generated event, pass that information:
+            if (mouseEvent->mInputSource ==
+                MouseEvent_Binding::MOZ_SOURCE_TOUCH) {
+              flags |= nsIFocusManager::FLAG_BYTOUCH;
+            }
+            fm->SetFocus(MOZ_KnownLive(newFocus->AsElement()), flags);
+          } else if (!suppressBlur) {
+            // clear the focus within the frame and then set it as the
+            // focused frame
+            EnsureDocument(mPresContext);
+            if (mDocument) {
+              nsCOMPtr<nsPIDOMWindowOuter> outerWindow = mDocument->GetWindow();
+#ifdef XP_MACOSX
+              if (!activeContent || !activeContent->IsXULElement())
+#endif
+                fm->ClearFocus(outerWindow);
+              // Prevent switch frame if we're already not in the foreground tab
+              // and we're in a content process.
+              // TODO: If we were inactive frame in this tab, and now in
+              //       background tab, we shouldn't make the tab foreground, but
+              //       we should set focus to clicked document in the background
+              //       tab.  However, nsFocusManager does not have proper method
+              //       for doing this.  Therefore, we should skip setting focus
+              //       to clicked document for now.
+              if (XRE_IsParentProcess() || IsInActiveTab(mDocument)) {
+                fm->SetFocusedWindow(outerWindow);
+              }
+            }
+          }
+        }
+
+        // The rest is left button-specific.
+        if (mouseEvent->mButton != MouseButton::ePrimary) {
+          break;
+        }
+
+        // The nearest enclosing element goes into the :active state.  If we're
+        // not an element (so we're text or something) we need to obtain
+        // our parent element and put it into :active instead.
+        if (activeContent && !activeContent->IsElement()) {
+          if (nsIContent* par = activeContent->GetFlattenedTreeParent()) {
+            activeContent = par;
+          }
+        }
+      } else {
+        // if we're here, the event handler returned false, so stop
+        // any of our own processing of a drag. Workaround for bug 43258.
+        StopTrackingDragGesture(true);
+      }
+      // XXX Why do we always set this is active?  Active window may be changed
+      //     by a mousedown event listener.
+      SetActiveManager(this, activeContent);
+    } break;
+    case ePointerCancel:
+    case ePointerUp: {
+      WidgetPointerEvent* pointerEvent = aEvent->AsPointerEvent();
+      MOZ_ASSERT(pointerEvent);
+      // Implicitly releasing capture for given pointer. ePointerLostCapture
+      // should be send after ePointerUp or ePointerCancel.
+      PointerEventHandler::ImplicitlyReleasePointerCapture(pointerEvent);
+      PointerEventHandler::UpdateActivePointerState(pointerEvent);
+
+      if (pointerEvent->mMessage == ePointerCancel ||
+          pointerEvent->mInputSource == MouseEvent_Binding::MOZ_SOURCE_TOUCH) {
+        // After pointercancel, pointer becomes invalid so we can remove
+        // relevant helper from table. Regarding pointerup with non-hoverable
+        // device, the pointer also becomes invalid. Hoverable (mouse/pen)
+        // pointers are valid all the time (not only between down/up).
+        GenerateMouseEnterExit(pointerEvent);
+        mPointersEnterLeaveHelper.Remove(pointerEvent->pointerId);
+      }
+      break;
+    }
+    case eMouseUp: {
+      // We can unconditionally stop capturing because
+      // we should never be capturing when the mouse button is up
+      PresShell::ReleaseCapturingContent();
+
+      ClearGlobalActiveContent(this);
+      WidgetMouseEvent* mouseUpEvent = aEvent->AsMouseEvent();
+      if (mouseUpEvent && EventCausesClickEvents(*mouseUpEvent)) {
+        // Make sure to dispatch the click even if there is no frame for
+        // the current target element. This is required for Web compatibility.
+        RefPtr<EventStateManager> esm =
+            ESMFromContentOrThis(aOverrideClickTarget);
+        ret =
+            esm->PostHandleMouseUp(mouseUpEvent, aStatus, aOverrideClickTarget);
+      }
+
+      if (PresShell* presShell = presContext->GetPresShell()) {
+        RefPtr<nsFrameSelection> frameSelection = presShell->FrameSelection();
+        frameSelection->SetDragState(false);
+      }
+    } break;
+    case eWheelOperationEnd: {
+      MOZ_ASSERT(aEvent->IsTrusted());
+      ScrollbarsForWheel::MayInactivate();
+      WidgetWheelEvent* wheelEvent = aEvent->AsWheelEvent();
+      nsIScrollableFrame* scrollTarget =
+          do_QueryFrame(ComputeScrollTargetAndMayAdjustWheelEvent(
+              mCurrentTarget, wheelEvent,
+              COMPUTE_DEFAULT_ACTION_TARGET_WITH_AUTO_DIR));
+      if (scrollTarget) {
+        scrollTarget->ScrollSnap();
+      }
+    } break;
+    case eWheel:
+    case eWheelOperationStart: {
+      MOZ_ASSERT(aEvent->IsTrusted());
+
+      if (*aStatus == nsEventStatus_eConsumeNoDefault) {
+        ScrollbarsForWheel::Inactivate();
+        break;
+      }
+
+      WidgetWheelEvent* wheelEvent = aEvent->AsWheelEvent();
+      MOZ_ASSERT(wheelEvent);
+
+      // When APZ is enabled, the actual scroll animation might be handled by
+      // the compositor.
+      WheelPrefs::Action action =
+          wheelEvent->mFlags.mHandledByAPZ
+              ? WheelPrefs::ACTION_NONE
+              : WheelPrefs::GetInstance()->ComputeActionFor(wheelEvent);
+
+      WheelDeltaAdjustmentStrategy strategy =
+          GetWheelDeltaAdjustmentStrategy(*wheelEvent);
+      // Adjust the delta values of the wheel event if the current default
+      // action is to horizontalize scrolling. I.e., deltaY values are set to
+      // deltaX and deltaY and deltaZ values are set to 0.
+      // If horizontalized, the delta values will be restored and its overflow
+      // deltaX will become 0 when the WheelDeltaHorizontalizer instance is
+      // being destroyed.
+      WheelDeltaHorizontalizer horizontalizer(*wheelEvent);
+      if (WheelDeltaAdjustmentStrategy::eHorizontalize == strategy) {
+        horizontalizer.Horizontalize();
+      }
+
+      // Since ComputeScrollTargetAndMayAdjustWheelEvent() may adjust the delta
+      // if the event is auto-dir. So we use |ESMAutoDirWheelDeltaRestorer|
+      // here.
+      // An instance of |ESMAutoDirWheelDeltaRestorer| is used to monitor
+      // auto-dir adjustment which may happen during its lifetime. If the delta
+      // values is adjusted during its lifetime, the instance will restore the
+      // adjusted delta when it's being destrcuted.
+      ESMAutoDirWheelDeltaRestorer restorer(*wheelEvent);
+      nsIFrame* frameToScroll = ComputeScrollTargetAndMayAdjustWheelEvent(
+          mCurrentTarget, wheelEvent,
+          COMPUTE_DEFAULT_ACTION_TARGET_WITH_AUTO_DIR);
+
+      switch (action) {
+        case WheelPrefs::ACTION_SCROLL:
+        case WheelPrefs::ACTION_HORIZONTALIZED_SCROLL: {
+          // For scrolling of default action, we should honor the mouse wheel
+          // transaction.
+
+          ScrollbarsForWheel::PrepareToScrollText(this, mCurrentTarget,
+                                                  wheelEvent);
+
+          if (aEvent->mMessage != eWheel ||
+              (!wheelEvent->mDeltaX && !wheelEvent->mDeltaY)) {
+            break;
+          }
+
+          nsIScrollableFrame* scrollTarget = do_QueryFrame(frameToScroll);
+          ScrollbarsForWheel::SetActiveScrollTarget(scrollTarget);
+
+          nsIFrame* rootScrollFrame =
+              !mCurrentTarget
+                  ? nullptr
+                  : mCurrentTarget->PresShell()->GetRootScrollFrame();
+          nsIScrollableFrame* rootScrollableFrame = nullptr;
+          if (rootScrollFrame) {
+            rootScrollableFrame = do_QueryFrame(rootScrollFrame);
+          }
+          if (!scrollTarget || scrollTarget == rootScrollableFrame) {
+            wheelEvent->mViewPortIsOverscrolled = true;
+          }
+          wheelEvent->mOverflowDeltaX = wheelEvent->mDeltaX;
+          wheelEvent->mOverflowDeltaY = wheelEvent->mDeltaY;
+          WheelPrefs::GetInstance()->CancelApplyingUserPrefsFromOverflowDelta(
+              wheelEvent);
+          if (scrollTarget) {
+            DoScrollText(scrollTarget, wheelEvent);
+          } else {
+            WheelTransaction::EndTransaction();
+            ScrollbarsForWheel::Inactivate();
+          }
+          break;
+        }
+        case WheelPrefs::ACTION_HISTORY: {
+          // If this event doesn't cause eLegacyMouseLineOrPageScroll event or
+          // the direction is oblique, don't perform history back/forward.
+          int32_t intDelta = wheelEvent->GetPreferredIntDelta();
+          if (!intDelta) {
+            break;
+          }
+          DoScrollHistory(intDelta);
+          break;
+        }
+        case WheelPrefs::ACTION_ZOOM: {
+          // If this event doesn't cause eLegacyMouseLineOrPageScroll event or
+          // the direction is oblique, don't perform zoom in/out.
+          int32_t intDelta = wheelEvent->GetPreferredIntDelta();
+          if (!intDelta) {
+            break;
+          }
+          DoScrollZoom(mCurrentTarget, intDelta);
+          break;
+        }
+        case WheelPrefs::ACTION_NONE:
+        default:
+          bool allDeltaOverflown = false;
+          if (wheelEvent->mFlags.mHandledByAPZ) {
+            if (wheelEvent->mCanTriggerSwipe) {
+              // For events that can trigger swipes, APZ needs to know whether
+              // scrolling is possible in the requested direction. It does this
+              // by looking at the scroll overflow values on mCanTriggerSwipe
+              // events after they have been processed.
+              allDeltaOverflown = !ComputeScrollTarget(
+                  mCurrentTarget, wheelEvent, COMPUTE_DEFAULT_ACTION_TARGET);
+            }
+          } else {
+            // The event was processed neither by APZ nor by us, so all of the
+            // delta values must be overflown delta values.
+            allDeltaOverflown = true;
+          }
+
+          if (!allDeltaOverflown) {
+            break;
+          }
+          wheelEvent->mOverflowDeltaX = wheelEvent->mDeltaX;
+          wheelEvent->mOverflowDeltaY = wheelEvent->mDeltaY;
+          WheelPrefs::GetInstance()->CancelApplyingUserPrefsFromOverflowDelta(
+              wheelEvent);
+          wheelEvent->mViewPortIsOverscrolled = true;
+          break;
+      }
+      *aStatus = nsEventStatus_eConsumeNoDefault;
+    } break;
+
+    case eGestureNotify: {
+      if (nsEventStatus_eConsumeNoDefault != *aStatus) {
+        DecideGestureEvent(aEvent->AsGestureNotifyEvent(), mCurrentTarget);
+      }
+    } break;
+
+    case eDragEnter:
+    case eDragOver: {
+      NS_ASSERTION(aEvent->mClass == eDragEventClass, "Expected a drag event");
+
+      // Check if the drag is occurring inside a scrollable area. If so, scroll
+      // the area when the mouse is near the edges.
+      if (mCurrentTarget && aEvent->mMessage == eDragOver) {
+        nsIFrame* checkFrame = mCurrentTarget;
+        while (checkFrame) {
+          nsIScrollableFrame* scrollFrame = do_QueryFrame(checkFrame);
+          // Break out so only the innermost scrollframe is scrolled.
+          if (scrollFrame && scrollFrame->DragScroll(aEvent)) {
+            break;
+          }
+          checkFrame = checkFrame->GetParent();
+        }
+      }
+
+      nsCOMPtr<nsIDragSession> dragSession = nsContentUtils::GetDragSession();
+      if (!dragSession) break;
+
+      // Reset the flag.
+      dragSession->SetOnlyChromeDrop(false);
+      if (mPresContext) {
+        EnsureDocument(mPresContext);
+      }
+      bool isChromeDoc = nsContentUtils::IsChromeDoc(mDocument);
+
+      // the initial dataTransfer is the one from the dragstart event that
+      // was set on the dragSession when the drag began.
+      RefPtr<DataTransfer> dataTransfer;
+      RefPtr<DataTransfer> initialDataTransfer = dragSession->GetDataTransfer();
+
+      WidgetDragEvent* dragEvent = aEvent->AsDragEvent();
+
+      // collect any changes to moz cursor settings stored in the event's
+      // data transfer.
+      UpdateDragDataTransfer(dragEvent);
+
+      // cancelling a dragenter or dragover event means that a drop should be
+      // allowed, so update the dropEffect and the canDrop state to indicate
+      // that a drag is allowed. If the event isn't cancelled, a drop won't be
+      // allowed. Essentially, to allow a drop somewhere, specify the effects
+      // using the effectAllowed and dropEffect properties in a dragenter or
+      // dragover event and cancel the event. To not allow a drop somewhere,
+      // don't cancel the event or set the effectAllowed or dropEffect to
+      // "none". This way, if the event is just ignored, no drop will be
+      // allowed.
+      uint32_t dropEffect = nsIDragService::DRAGDROP_ACTION_NONE;
+      uint32_t action = nsIDragService::DRAGDROP_ACTION_NONE;
+      if (nsEventStatus_eConsumeNoDefault == *aStatus) {
+        // If the event has initialized its mDataTransfer, use it.
+        // Or the event has not been initialized its mDataTransfer, but
+        // it's set before dispatch because of synthesized, but without
+        // testing session (e.g., emulating drag from another app), use it
+        // coming from outside.
+        // XXX Perhaps, for the latter case, we need new API because we don't
+        //     have a chance to initialize allowed effects of the session.
+        if (dragEvent->mDataTransfer) {
+          // get the dataTransfer and the dropEffect that was set on it
+          dataTransfer = dragEvent->mDataTransfer;
+          dropEffect = dataTransfer->DropEffectInt();
+        } else {
+          // if dragEvent->mDataTransfer is null, it means that no attempt was
+          // made to access the dataTransfer during the event, yet the event
+          // was cancelled. Instead, use the initial data transfer available
+          // from the drag session. The drop effect would not have been
+          // initialized (which is done in DragEvent::GetDataTransfer),
+          // so set it from the drag action. We'll still want to filter it
+          // based on the effectAllowed below.
+          dataTransfer = initialDataTransfer;
+
+          dragSession->GetDragAction(&action);
+
+          // filter the drop effect based on the action. Use UNINITIALIZED as
+          // any effect is allowed.
+          dropEffect = nsContentUtils::FilterDropEffect(
+              action, nsIDragService::DRAGDROP_ACTION_UNINITIALIZED);
+        }
+
+        // At this point, if the dataTransfer is null, it means that the
+        // drag was originally started by directly calling the drag service.
+        // Just assume that all effects are allowed.
+        uint32_t effectAllowed = nsIDragService::DRAGDROP_ACTION_UNINITIALIZED;
+        if (dataTransfer) {
+          effectAllowed = dataTransfer->EffectAllowedInt();
+        }
+
+        // set the drag action based on the drop effect and effect allowed.
+        // The drop effect field on the drag transfer object specifies the
+        // desired current drop effect. However, it cannot be used if the
+        // effectAllowed state doesn't include that type of action. If the
+        // dropEffect is "none", then the action will be 'none' so a drop will
+        // not be allowed.
+        if (effectAllowed == nsIDragService::DRAGDROP_ACTION_UNINITIALIZED ||
+            dropEffect & effectAllowed)
+          action = dropEffect;
+
+        if (action == nsIDragService::DRAGDROP_ACTION_NONE)
+          dropEffect = nsIDragService::DRAGDROP_ACTION_NONE;
+
+        // inform the drag session that a drop is allowed on this node.
+        dragSession->SetDragAction(action);
+        dragSession->SetCanDrop(action != nsIDragService::DRAGDROP_ACTION_NONE);
+
+        // For now, do this only for dragover.
+        // XXXsmaug dragenter needs some more work.
+        if (aEvent->mMessage == eDragOver && !isChromeDoc) {
+          // Someone has called preventDefault(), check whether is was on
+          // content or chrome.
+          dragSession->SetOnlyChromeDrop(
+              !dragEvent->mDefaultPreventedOnContent);
+        }
+      } else if (aEvent->mMessage == eDragOver && !isChromeDoc) {
+        // No one called preventDefault(), so handle drop only in chrome.
+        dragSession->SetOnlyChromeDrop(true);
+      }
+      if (ContentChild* child = ContentChild::GetSingleton()) {
+        child->SendUpdateDropEffect(action, dropEffect);
+      }
+      if (aEvent->HasBeenPostedToRemoteProcess()) {
+        dragSession->SetCanDrop(true);
+      } else if (initialDataTransfer) {
+        // Now set the drop effect in the initial dataTransfer. This ensures
+        // that we can get the desired drop effect in the drop event. For events
+        // dispatched to content, the content process will take care of setting
+        // this.
+        initialDataTransfer->SetDropEffectInt(dropEffect);
+      }
+    } break;
+
+    case eDrop: {
+      if (aEvent->mFlags.mIsSynthesizedForTests) {
+        if (nsCOMPtr<nsIDragSession> dragSession =
+                nsContentUtils::GetDragSession()) {
+          MOZ_ASSERT(dragSession->IsSynthesizedForTests());
+          RefPtr<WindowContext> sourceWC;
+          DebugOnly<nsresult> rvIgnored =
+              dragSession->GetSourceWindowContext(getter_AddRefs(sourceWC));
+          NS_WARNING_ASSERTION(
+              NS_SUCCEEDED(rvIgnored),
+              "nsIDragSession::GetSourceDocument() failed, but ignored");
+          // If the drag source hasn't been initialized, i.e., dragstart was
+          // consumed by the test, the test needs to dispatch "dragend" event
+          // instead of the drag session.  Therefore, it does not make sense
+          // to set drag end point in such case (you hit assersion if you do
+          // it).
+          if (sourceWC) {
+            CSSIntPoint dropPointInScreen =
+                Event::GetScreenCoords(aPresContext, aEvent, aEvent->mRefPoint)
+                    .extract();
+            dragSession->SetDragEndPointForTests(dropPointInScreen.x,
+                                                 dropPointInScreen.y);
+          }
+        }
+      }
+      sLastDragOverFrame = nullptr;
+      ClearGlobalActiveContent(this);
+      break;
+    }
+    case eDragExit:
+      // make sure to fire the enter and exit_synth events after the
+      // eDragExit event, otherwise we'll clean up too early
+      GenerateDragDropEnterExit(presContext, aEvent->AsDragEvent());
+      if (ContentChild* child = ContentChild::GetSingleton()) {
+        // SendUpdateDropEffect to prevent nsIDragService from waiting for
+        // response of forwarded dragexit event.
+        child->SendUpdateDropEffect(nsIDragService::DRAGDROP_ACTION_NONE,
+                                    nsIDragService::DRAGDROP_ACTION_NONE);
+      }
+      break;
+
+    case eKeyUp:
+      // If space key is released, we need to inactivate the element which was
+      // activated by preceding space key down.
+      // XXX Currently, we don't store the reason of activation.  Therefore,
+      //     this may cancel what is activated by a mousedown, but it must not
+      //     cause actual problem in web apps in the wild since it must be
+      //     rare case that users release space key during a mouse click/drag.
+      if (aEvent->AsKeyboardEvent()->ShouldWorkAsSpaceKey()) {
+        ClearGlobalActiveContent(this);
+      }
+      break;
+
+    case eKeyPress: {
+      WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
+      PostHandleKeyboardEvent(keyEvent, mCurrentTarget, *aStatus);
+    } break;
+
+    case eMouseEnterIntoWidget:
+      if (mCurrentTarget) {
+        nsCOMPtr<nsIContent> targetContent;
+        mCurrentTarget->GetContentForEvent(aEvent,
+                                           getter_AddRefs(targetContent));
+        SetContentState(targetContent, ElementState::HOVER);
+      }
+      break;
+
+    case eMouseExitFromWidget:
+      PointerEventHandler::UpdateActivePointerState(aEvent->AsMouseEvent());
+      break;
+
+#ifdef XP_MACOSX
+    case eMouseActivate:
+      if (mCurrentTarget) {
+        nsCOMPtr<nsIContent> targetContent;
+        mCurrentTarget->GetContentForEvent(aEvent,
+                                           getter_AddRefs(targetContent));
+        if (!NodeAllowsClickThrough(targetContent)) {
+          *aStatus = nsEventStatus_eConsumeNoDefault;
+        }
+      }
+      break;
+#endif
+
+    default:
+      break;
+  }
+
+  // Reset target frame to null to avoid mistargeting after reentrant event
+  mCurrentTarget = nullptr;
+  mCurrentTargetContent = nullptr;
+
+  return ret;
+}
+
+BrowserParent* EventStateManager::GetCrossProcessTarget() {
+  return IMEStateManager::GetActiveBrowserParent();
+}
+
+bool EventStateManager::IsTargetCrossProcess(WidgetGUIEvent* aEvent) {
+  // Check to see if there is a focused, editable content in chrome,
+  // in that case, do not forward IME events to content
+  Element* focusedElement = GetFocusedElement();
+  if (focusedElement && focusedElement->IsEditable()) {
+    return false;
+  }
+  return IMEStateManager::GetActiveBrowserParent() != nullptr;
+}
+
+void EventStateManager::NotifyDestroyPresContext(nsPresContext* aPresContext) {
+  RefPtr<nsPresContext> presContext = aPresContext;
+  if (presContext) {
+    IMEStateManager::OnDestroyPresContext(*presContext);
+  }
+
+  // Bug 70855: Presentation is going away, possibly for a reframe.
+  // Reset the hover state so that if we're recreating the presentation,
+  // we won't have the old hover state still set in the new presentation,
+  // as if the new presentation is resized, a new element may be hovered.
+  ResetHoverState();
+
+  mPointersEnterLeaveHelper.Clear();
+  PointerEventHandler::NotifyDestroyPresContext(presContext);
+}
+
+void EventStateManager::ResetHoverState() {
+  if (mHoverContent) {
+    SetContentState(nullptr, ElementState::HOVER);
+  }
+}
+
+void EventStateManager::SetPresContext(nsPresContext* aPresContext) {
+  mPresContext = aPresContext;
+}
+
+void EventStateManager::ClearFrameRefs(nsIFrame* aFrame) {
+  if (aFrame && aFrame == mCurrentTarget) {
+    mCurrentTargetContent = aFrame->GetContent();
+  }
+}
+
+struct CursorImage {
+  gfx::IntPoint mHotspot;
+  nsCOMPtr<imgIContainer> mContainer;
+  ImageResolution mResolution;
+  bool mEarlierCursorLoading = false;
+};
+
+// Given the event that we're processing, and the computed cursor and hotspot,
+// determine whether the custom CSS cursor should be blocked (that is, not
+// honored).
+//
+// We will not honor it all of the following are true:
+//
+//  * layout.cursor.block.enabled is true.
+//  * the size of the custom cursor is bigger than layout.cursor.block.max-size.
+//  * the bounds of the cursor would end up outside of the viewport of the
+//    top-level content document.
+//
+// This is done in order to prevent hijacking the cursor, see bug 1445844 and
+// co.
+static bool ShouldBlockCustomCursor(nsPresContext* aPresContext,
+                                    WidgetEvent* aEvent,
+                                    const CursorImage& aCursor) {
+  if (!StaticPrefs::layout_cursor_block_enabled()) {
+    return false;
+  }
+
+  int32_t width = 0;
+  int32_t height = 0;
+  aCursor.mContainer->GetWidth(&width);
+  aCursor.mContainer->GetHeight(&height);
+  aCursor.mResolution.ApplyTo(width, height);
+
+  int32_t maxSize = StaticPrefs::layout_cursor_block_max_size();
+
+  if (width <= maxSize && height <= maxSize) {
+    return false;
+  }
+
+  auto input = DOMIntersectionObserver::ComputeInput(*aPresContext->Document(),
+                                                     nullptr, nullptr);
+
+  if (!input.mRootFrame) {
+    return false;
+  }
+
+  nsPoint point = nsLayoutUtils::GetEventCoordinatesRelativeTo(
+      aEvent, RelativeTo{input.mRootFrame});
+
+  // The cursor size won't be affected by our full zoom in the parent process,
+  // so undo that before checking the rect.
+  float zoom = aPresContext->GetFullZoom();
+
+  // Also adjust for accessibility cursor scaling factor.
+  zoom /= LookAndFeel::GetFloat(LookAndFeel::FloatID::CursorScale, 1.0f);
+
+  nsSize size(CSSPixel::ToAppUnits(width / zoom),
+              CSSPixel::ToAppUnits(height / zoom));
+  nsPoint hotspot(CSSPixel::ToAppUnits(aCursor.mHotspot.x / zoom),
+                  CSSPixel::ToAppUnits(aCursor.mHotspot.y / zoom));
+
+  const nsRect cursorRect(point - hotspot, size);
+  auto output = DOMIntersectionObserver::Intersect(input, cursorRect);
+  return !output.mIntersectionRect ||
+         !(*output.mIntersectionRect == cursorRect);
+}
+
+static gfx::IntPoint ComputeHotspot(imgIContainer* aContainer,
+                                    const Maybe<gfx::Point>& aHotspot) {
+  MOZ_ASSERT(aContainer);
+
+  // css3-ui says to use the CSS-specified hotspot if present,
+  // otherwise use the intrinsic hotspot, otherwise use the top left
+  // corner.
+  if (aHotspot) {
+    int32_t imgWidth, imgHeight;
+    aContainer->GetWidth(&imgWidth);
+    aContainer->GetHeight(&imgHeight);
+    auto hotspot = gfx::IntPoint::Round(*aHotspot);
+    return {std::max(std::min(hotspot.x.value, imgWidth - 1), 0),
+            std::max(std::min(hotspot.y.value, imgHeight - 1), 0)};
+  }
+
+  gfx::IntPoint hotspot;
+  aContainer->GetHotspotX(&hotspot.x.value);
+  aContainer->GetHotspotY(&hotspot.y.value);
+  return hotspot;
+}
+
+static CursorImage ComputeCustomCursor(nsPresContext* aPresContext,
+                                       WidgetEvent* aEvent,
+                                       const nsIFrame& aFrame,
+                                       const nsIFrame::Cursor& aCursor) {
+  if (aCursor.mAllowCustomCursor == nsIFrame::AllowCustomCursorImage::No) {
+    return {};
+  }
+  const ComputedStyle& style =
+      aCursor.mStyle ? *aCursor.mStyle : *aFrame.Style();
+
+  // If we are falling back because any cursor before us is loading, let the
+  // consumer know.
+  bool loading = false;
+  for (const auto& image : style.StyleUI()->Cursor().images.AsSpan()) {
+    MOZ_ASSERT(image.image.IsImageRequestType(),
+               "Cursor image should only parse url() types");
+    uint32_t status;
+    imgRequestProxy* req = image.image.GetImageRequest();
+    if (!req || NS_FAILED(req->GetImageStatus(&status))) {
+      continue;
+    }
+    if (!(status & imgIRequest::STATUS_LOAD_COMPLETE)) {
+      loading = true;
+      continue;
+    }
+    if (status & imgIRequest::STATUS_ERROR) {
+      continue;
+    }
+    nsCOMPtr<imgIContainer> container;
+    req->GetImage(getter_AddRefs(container));
+    if (!container) {
+      continue;
+    }
+    StyleImageOrientation orientation =
+        aFrame.StyleVisibility()->UsedImageOrientation(req);
+    container = nsLayoutUtils::OrientImage(container, orientation);
+    Maybe<gfx::Point> specifiedHotspot =
+        image.has_hotspot ? Some(gfx::Point{image.hotspot_x, image.hotspot_y})
+                          : Nothing();
+    gfx::IntPoint hotspot = ComputeHotspot(container, specifiedHotspot);
+    CursorImage result{hotspot, std::move(container),
+                       image.image.GetResolution(), loading};
+    if (ShouldBlockCustomCursor(aPresContext, aEvent, result)) {
+      continue;
+    }
+    // This is the one we want!
+    return result;
+  }
+  return {{}, nullptr, {}, loading};
+}
+
+void EventStateManager::UpdateCursor(nsPresContext* aPresContext,
+                                     WidgetEvent* aEvent,
+                                     nsIFrame* aTargetFrame,
+                                     nsEventStatus* aStatus) {
+  if (aTargetFrame && IsRemoteTarget(aTargetFrame->GetContent())) {
+    return;
+  }
+
+  auto cursor = StyleCursorKind::Default;
+  nsCOMPtr<imgIContainer> container;
+  ImageResolution resolution;
+  Maybe<gfx::IntPoint> hotspot;
+
+  // If cursor is locked just use the locked one
+  if (mLockCursor != kInvalidCursorKind) {
+    cursor = mLockCursor;
+  }
+  // If not locked, look for correct cursor
+  else if (aTargetFrame) {
+    nsPoint pt = nsLayoutUtils::GetEventCoordinatesRelativeTo(
+        aEvent, RelativeTo{aTargetFrame});
+    Maybe<nsIFrame::Cursor> framecursor = aTargetFrame->GetCursor(pt);
+    // Avoid setting cursor when the mouse is over a windowless plugin.
+    if (!framecursor) {
+      if (XRE_IsContentProcess()) {
+        mLastFrameConsumedSetCursor = true;
+      }
+      return;
+    }
+    // Make sure cursors get reset after the mouse leaves a
+    // windowless plugin frame.
+    if (mLastFrameConsumedSetCursor) {
+      ClearCachedWidgetCursor(aTargetFrame);
+      mLastFrameConsumedSetCursor = false;
+    }
+
+    const CursorImage customCursor =
+        ComputeCustomCursor(aPresContext, aEvent, *aTargetFrame, *framecursor);
+
+    // If the current cursor is from the same frame, and it is now
+    // loading some new image for the cursor, we should wait for a
+    // while rather than taking its fallback cursor directly.
+    if (customCursor.mEarlierCursorLoading &&
+        gLastCursorSourceFrame == aTargetFrame &&
+        TimeStamp::NowLoRes() - gLastCursorUpdateTime <
+            TimeDuration::FromMilliseconds(kCursorLoadingTimeout)) {
+      return;
+    }
+    cursor = framecursor->mCursor;
+    container = std::move(customCursor.mContainer);
+    resolution = customCursor.mResolution;
+    hotspot = Some(customCursor.mHotspot);
+  }
+
+  if (StaticPrefs::ui_use_activity_cursor()) {
+    // Check whether or not to show the busy cursor
+    nsCOMPtr<nsIDocShell> docShell(aPresContext->GetDocShell());
+    if (!docShell) return;
+    auto busyFlags = docShell->GetBusyFlags();
+
+    // Show busy cursor everywhere before page loads
+    // and just replace the arrow cursor after page starts loading
+    if (busyFlags & nsIDocShell::BUSY_FLAGS_BUSY &&
+        (cursor == StyleCursorKind::Auto ||
+         cursor == StyleCursorKind::Default)) {
+      cursor = StyleCursorKind::Progress;
+      container = nullptr;
+    }
+  }
+
+  if (aTargetFrame) {
+    SetCursor(cursor, container, resolution, hotspot,
+              aTargetFrame->GetNearestWidget(), false);
+    gLastCursorSourceFrame = aTargetFrame;
+    gLastCursorUpdateTime = TimeStamp::NowLoRes();
+  }
+
+  if (mLockCursor != kInvalidCursorKind || StyleCursorKind::Auto != cursor) {
+    *aStatus = nsEventStatus_eConsumeDoDefault;
+  }
+}
+
+void EventStateManager::ClearCachedWidgetCursor(nsIFrame* aTargetFrame) {
+  if (!aTargetFrame) {
+    return;
+  }
+  nsIWidget* aWidget = aTargetFrame->GetNearestWidget();
+  if (!aWidget) {
+    return;
+  }
+  aWidget->ClearCachedCursor();
+}
+
+nsresult EventStateManager::SetCursor(StyleCursorKind aCursor,
+                                      imgIContainer* aContainer,
+                                      const ImageResolution& aResolution,
+                                      const Maybe<gfx::IntPoint>& aHotspot,
+                                      nsIWidget* aWidget, bool aLockCursor) {
+  EnsureDocument(mPresContext);
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_FAILURE);
+  sMouseOverDocument = mDocument.get();
+
+  NS_ENSURE_TRUE(aWidget, NS_ERROR_FAILURE);
+  if (aLockCursor) {
+    if (StyleCursorKind::Auto != aCursor) {
+      mLockCursor = aCursor;
+    } else {
+      // If cursor style is set to auto we unlock the cursor again.
+      mLockCursor = kInvalidCursorKind;
+    }
+  }
+  nsCursor c;
+  switch (aCursor) {
+    case StyleCursorKind::Auto:
+    case StyleCursorKind::Default:
+      c = eCursor_standard;
+      break;
+    case StyleCursorKind::Pointer:
+      c = eCursor_hyperlink;
+      break;
+    case StyleCursorKind::Crosshair:
+      c = eCursor_crosshair;
+      break;
+    case StyleCursorKind::Move:
+      c = eCursor_move;
+      break;
+    case StyleCursorKind::Text:
+      c = eCursor_select;
+      break;
+    case StyleCursorKind::Wait:
+      c = eCursor_wait;
+      break;
+    case StyleCursorKind::Help:
+      c = eCursor_help;
+      break;
+    case StyleCursorKind::NResize:
+      c = eCursor_n_resize;
+      break;
+    case StyleCursorKind::SResize:
+      c = eCursor_s_resize;
+      break;
+    case StyleCursorKind::WResize:
+      c = eCursor_w_resize;
+      break;
+    case StyleCursorKind::EResize:
+      c = eCursor_e_resize;
+      break;
+    case StyleCursorKind::NwResize:
+      c = eCursor_nw_resize;
+      break;
+    case StyleCursorKind::SeResize:
+      c = eCursor_se_resize;
+      break;
+    case StyleCursorKind::NeResize:
+      c = eCursor_ne_resize;
+      break;
+    case StyleCursorKind::SwResize:
+      c = eCursor_sw_resize;
+      break;
+    case StyleCursorKind::Copy:  // CSS3
+      c = eCursor_copy;
+      break;
+    case StyleCursorKind::Alias:
+      c = eCursor_alias;
+      break;
+    case StyleCursorKind::ContextMenu:
+      c = eCursor_context_menu;
+      break;
+    case StyleCursorKind::Cell:
+      c = eCursor_cell;
+      break;
+    case StyleCursorKind::Grab:
+      c = eCursor_grab;
+      break;
+    case StyleCursorKind::Grabbing:
+      c = eCursor_grabbing;
+      break;
+    case StyleCursorKind::Progress:
+      c = eCursor_spinning;
+      break;
+    case StyleCursorKind::ZoomIn:
+      c = eCursor_zoom_in;
+      break;
+    case StyleCursorKind::ZoomOut:
+      c = eCursor_zoom_out;
+      break;
+    case StyleCursorKind::NotAllowed:
+      c = eCursor_not_allowed;
+      break;
+    case StyleCursorKind::ColResize:
+      c = eCursor_col_resize;
+      break;
+    case StyleCursorKind::RowResize:
+      c = eCursor_row_resize;
+      break;
+    case StyleCursorKind::NoDrop:
+      c = eCursor_no_drop;
+      break;
+    case StyleCursorKind::VerticalText:
+      c = eCursor_vertical_text;
+      break;
+    case StyleCursorKind::AllScroll:
+      c = eCursor_all_scroll;
+      break;
+    case StyleCursorKind::NeswResize:
+      c = eCursor_nesw_resize;
+      break;
+    case StyleCursorKind::NwseResize:
+      c = eCursor_nwse_resize;
+      break;
+    case StyleCursorKind::NsResize:
+      c = eCursor_ns_resize;
+      break;
+    case StyleCursorKind::EwResize:
+      c = eCursor_ew_resize;
+      break;
+    case StyleCursorKind::None:
+      c = eCursor_none;
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Unknown cursor kind");
+      c = eCursor_standard;
+      break;
+  }
+
+  uint32_t x = aHotspot ? aHotspot->x.value : 0;
+  uint32_t y = aHotspot ? aHotspot->y.value : 0;
+  aWidget->SetCursor(nsIWidget::Cursor{c, aContainer, x, y, aResolution});
+  return NS_OK;
+}
+
+class MOZ_STACK_CLASS ESMEventCB : public EventDispatchingCallback {
+ public:
+  explicit ESMEventCB(nsIContent* aTarget) : mTarget(aTarget) {}
+
+  MOZ_CAN_RUN_SCRIPT
+  void HandleEvent(EventChainPostVisitor& aVisitor) override {
+    if (aVisitor.mPresContext) {
+      nsIFrame* frame = aVisitor.mPresContext->GetPrimaryFrameFor(mTarget);
+      if (frame) {
+        frame->HandleEvent(aVisitor.mPresContext, aVisitor.mEvent->AsGUIEvent(),
+                           &aVisitor.mEventStatus);
+      }
+    }
+  }
+
+  nsCOMPtr<nsIContent> mTarget;
+};
+
+static UniquePtr<WidgetMouseEvent> CreateMouseOrPointerWidgetEvent(
+    WidgetMouseEvent* aMouseEvent, EventMessage aMessage,
+    EventTarget* aRelatedTarget) {
+  WidgetPointerEvent* sourcePointer = aMouseEvent->AsPointerEvent();
+  UniquePtr<WidgetMouseEvent> newEvent;
+  if (sourcePointer) {
+    AUTO_PROFILER_LABEL("CreateMouseOrPointerWidgetEvent", OTHER);
+
+    WidgetPointerEvent* newPointerEvent = new WidgetPointerEvent(
+        aMouseEvent->IsTrusted(), aMessage, aMouseEvent->mWidget);
+    newPointerEvent->mIsPrimary = sourcePointer->mIsPrimary;
+    newPointerEvent->mWidth = sourcePointer->mWidth;
+    newPointerEvent->mHeight = sourcePointer->mHeight;
+    newPointerEvent->mInputSource = sourcePointer->mInputSource;
+
+    newEvent = WrapUnique(newPointerEvent);
+  } else {
+    newEvent = MakeUnique<WidgetMouseEvent>(aMouseEvent->IsTrusted(), aMessage,
+                                            aMouseEvent->mWidget,
+                                            WidgetMouseEvent::eReal);
+  }
+  newEvent->mRelatedTarget = aRelatedTarget;
+  newEvent->mRefPoint = aMouseEvent->mRefPoint;
+  newEvent->mModifiers = aMouseEvent->mModifiers;
+  newEvent->mButton = aMouseEvent->mButton;
+  newEvent->mButtons = aMouseEvent->mButtons;
+  newEvent->mPressure = aMouseEvent->mPressure;
+  newEvent->mInputSource = aMouseEvent->mInputSource;
+  newEvent->pointerId = aMouseEvent->pointerId;
+
+  return newEvent;
+}
+
+nsIFrame* EventStateManager::DispatchMouseOrPointerEvent(
+    WidgetMouseEvent* aMouseEvent, EventMessage aMessage,
+    nsIContent* aTargetContent, nsIContent* aRelatedContent) {
+  // http://dvcs.w3.org/hg/webevents/raw-file/default/mouse-lock.html#methods
+  // "[When the mouse is locked on an element...e]vents that require the concept
+  // of a mouse cursor must not be dispatched (for example: mouseover,
+  // mouseout).
+  if (PointerLockManager::IsLocked() &&
+      (aMessage == eMouseLeave || aMessage == eMouseEnter ||
+       aMessage == eMouseOver || aMessage == eMouseOut)) {
+    mCurrentTargetContent = nullptr;
+    nsCOMPtr<Element> pointerLockedElement =
+        PointerLockManager::GetLockedElement();
+    if (!pointerLockedElement) {
+      NS_WARNING("Should have pointer locked element, but didn't.");
+      return nullptr;
+    }
+    return mPresContext->GetPrimaryFrameFor(pointerLockedElement);
+  }
+
+  mCurrentTargetContent = nullptr;
+
+  if (!aTargetContent) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIContent> targetContent = aTargetContent;
+  nsCOMPtr<nsIContent> relatedContent = aRelatedContent;
+
+  UniquePtr<WidgetMouseEvent> dispatchEvent =
+      CreateMouseOrPointerWidgetEvent(aMouseEvent, aMessage, relatedContent);
+
+  AutoWeakFrame previousTarget = mCurrentTarget;
+  mCurrentTargetContent = targetContent;
+
+  nsIFrame* targetFrame = nullptr;
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  ESMEventCB callback(targetContent);
+  RefPtr<nsPresContext> presContext = mPresContext;
+  EventDispatcher::Dispatch(targetContent, presContext, dispatchEvent.get(),
+                            nullptr, &status, &callback);
+
+  if (mPresContext) {
+    // Although the primary frame was checked in event callback, it may not be
+    // the same object after event dispatch and handling, so refetch it.
+    targetFrame = mPresContext->GetPrimaryFrameFor(targetContent);
+
+    // If we are entering/leaving remote content, dispatch a mouse enter/exit
+    // event to the remote frame.
+    if (IsTopLevelRemoteTarget(targetContent)) {
+      if (aMessage == eMouseOut) {
+        // For remote content, send a puppet widget mouse exit event.
+        UniquePtr<WidgetMouseEvent> remoteEvent =
+            CreateMouseOrPointerWidgetEvent(aMouseEvent, eMouseExitFromWidget,
+                                            relatedContent);
+        remoteEvent->mExitFrom = Some(WidgetMouseEvent::ePuppet);
+
+        // mCurrentTarget is set to the new target, so we must reset it to the
+        // old target and then dispatch a cross-process event. (mCurrentTarget
+        // will be set back below.) HandleCrossProcessEvent will query for the
+        // proper target via GetEventTarget which will return mCurrentTarget.
+        mCurrentTarget = targetFrame;
+        HandleCrossProcessEvent(remoteEvent.get(), &status);
+      } else if (aMessage == eMouseOver) {
+        UniquePtr<WidgetMouseEvent> remoteEvent =
+            CreateMouseOrPointerWidgetEvent(aMouseEvent, eMouseEnterIntoWidget,
+                                            relatedContent);
+        HandleCrossProcessEvent(remoteEvent.get(), &status);
+      }
+    }
+  }
+
+  mCurrentTargetContent = nullptr;
+  mCurrentTarget = previousTarget;
+
+  return targetFrame;
+}
+
+static nsIContent* FindCommonAncestor(nsIContent* aNode1, nsIContent* aNode2) {
+  if (!aNode1 || !aNode2) {
+    return nullptr;
+  }
+  return nsContentUtils::GetCommonFlattenedTreeAncestor(aNode1, aNode2);
+}
+
+class EnterLeaveDispatcher {
+ public:
+  EnterLeaveDispatcher(EventStateManager* aESM, nsIContent* aTarget,
+                       nsIContent* aRelatedTarget,
+                       WidgetMouseEvent* aMouseEvent,
+                       EventMessage aEventMessage)
+      : mESM(aESM), mMouseEvent(aMouseEvent), mEventMessage(aEventMessage) {
+    nsPIDOMWindowInner* win =
+        aTarget ? aTarget->OwnerDoc()->GetInnerWindow() : nullptr;
+    if (aMouseEvent->AsPointerEvent()
+            ? win && win->HasPointerEnterLeaveEventListeners()
+            : win && win->HasMouseEnterLeaveEventListeners()) {
+      mRelatedTarget =
+          aRelatedTarget ? aRelatedTarget->FindFirstNonChromeOnlyAccessContent()
+                         : nullptr;
+      nsINode* commonParent = FindCommonAncestor(aTarget, aRelatedTarget);
+      nsIContent* current = aTarget;
+      // Note, it is ok if commonParent is null!
+      while (current && current != commonParent) {
+        if (!current->ChromeOnlyAccess()) {
+          mTargets.AppendObject(current);
+        }
+        // mouseenter/leave is fired only on elements.
+        current = current->GetFlattenedTreeParent();
+      }
+    }
+  }
+
+  // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY void Dispatch() {
+    if (mEventMessage == eMouseEnter || mEventMessage == ePointerEnter) {
+      for (int32_t i = mTargets.Count() - 1; i >= 0; --i) {
+        mESM->DispatchMouseOrPointerEvent(mMouseEvent, mEventMessage,
+                                          MOZ_KnownLive(mTargets[i]),
+                                          mRelatedTarget);
+      }
+    } else {
+      for (int32_t i = 0; i < mTargets.Count(); ++i) {
+        mESM->DispatchMouseOrPointerEvent(mMouseEvent, mEventMessage,
+                                          MOZ_KnownLive(mTargets[i]),
+                                          mRelatedTarget);
+      }
+    }
+  }
+
+  // Nothing overwrites anything after constructor. Please remove MOZ_KnownLive
+  // and MOZ_KNOWN_LIVE if anything marked as such becomes mutable.
+  const RefPtr<EventStateManager> mESM;
+  nsCOMArray<nsIContent> mTargets;
+  MOZ_KNOWN_LIVE nsCOMPtr<nsIContent> mRelatedTarget;
+  WidgetMouseEvent* mMouseEvent;
+  EventMessage mEventMessage;
+};
+
+void EventStateManager::NotifyMouseOut(WidgetMouseEvent* aMouseEvent,
+                                       nsIContent* aMovingInto) {
+  RefPtr<OverOutElementsWrapper> wrapper = GetWrapperByEventID(aMouseEvent);
+
+  if (!wrapper || !wrapper->mLastOverElement) {
+    return;
+  }
+  // Before firing mouseout, check for recursion
+  if (wrapper->mLastOverElement == wrapper->mFirstOutEventElement) {
+    return;
+  }
+
+  if (RefPtr<nsFrameLoaderOwner> flo =
+          do_QueryObject(wrapper->mLastOverElement)) {
+    if (BrowsingContext* bc = flo->GetExtantBrowsingContext()) {
+      if (nsIDocShell* docshell = bc->GetDocShell()) {
+        if (RefPtr<nsPresContext> presContext = docshell->GetPresContext()) {
+          EventStateManager* kidESM = presContext->EventStateManager();
+          // Not moving into any element in this subdocument
+          kidESM->NotifyMouseOut(aMouseEvent, nullptr);
+        }
+      }
+    }
+  }
+  // That could have caused DOM events which could wreak havoc. Reverify
+  // things and be careful.
+  if (!wrapper->mLastOverElement) {
+    return;
+  }
+
+  // Store the first mouseOut event we fire and don't refire mouseOut
+  // to that element while the first mouseOut is still ongoing.
+  wrapper->mFirstOutEventElement = wrapper->mLastOverElement;
+
+  // Don't touch hover state if aMovingInto is non-null.  Caller will update
+  // hover state itself, and we have optimizations for hover switching between
+  // two nearby elements both deep in the DOM tree that would be defeated by
+  // switching the hover state to null here.
+  bool isPointer = aMouseEvent->mClass == ePointerEventClass;
+  if (!aMovingInto && !isPointer) {
+    // Unset :hover
+    SetContentState(nullptr, ElementState::HOVER);
+  }
+
+  EnterLeaveDispatcher leaveDispatcher(this, wrapper->mLastOverElement,
+                                       aMovingInto, aMouseEvent,
+                                       isPointer ? ePointerLeave : eMouseLeave);
+
+  // Fire mouseout
+  nsCOMPtr<nsIContent> lastOverElement = wrapper->mLastOverElement;
+  DispatchMouseOrPointerEvent(aMouseEvent, isPointer ? ePointerOut : eMouseOut,
+                              lastOverElement, aMovingInto);
+  leaveDispatcher.Dispatch();
+
+  wrapper->mLastOverFrame = nullptr;
+  wrapper->mLastOverElement = nullptr;
+
+  // Turn recursion protection back off
+  wrapper->mFirstOutEventElement = nullptr;
+}
+
+void EventStateManager::RecomputeMouseEnterStateForRemoteFrame(
+    Element& aElement) {
+  if (!mMouseEnterLeaveHelper ||
+      mMouseEnterLeaveHelper->mLastOverElement != &aElement) {
+    return;
+  }
+
+  if (BrowserParent* remote = BrowserParent::GetFrom(&aElement)) {
+    remote->MouseEnterIntoWidget();
+  }
+}
+
+void EventStateManager::NotifyMouseOver(WidgetMouseEvent* aMouseEvent,
+                                        nsIContent* aContent) {
+  NS_ASSERTION(aContent, "Mouse must be over something");
+
+  RefPtr<OverOutElementsWrapper> wrapper = GetWrapperByEventID(aMouseEvent);
+
+  if (!wrapper || wrapper->mLastOverElement == aContent) return;
+
+  // Before firing mouseover, check for recursion
+  if (aContent == wrapper->mFirstOverEventElement) return;
+
+  // Check to see if we're a subdocument and if so update the parent
+  // document's ESM state to indicate that the mouse is over the
+  // content associated with our subdocument.
+  EnsureDocument(mPresContext);
+  if (Document* parentDoc = mDocument->GetInProcessParentDocument()) {
+    if (nsCOMPtr<nsIContent> docContent = mDocument->GetEmbedderElement()) {
+      if (PresShell* parentPresShell = parentDoc->GetPresShell()) {
+        RefPtr<EventStateManager> parentESM =
+            parentPresShell->GetPresContext()->EventStateManager();
+        parentESM->NotifyMouseOver(aMouseEvent, docContent);
+      }
+    }
+  }
+  // Firing the DOM event in the parent document could cause all kinds
+  // of havoc.  Reverify and take care.
+  if (wrapper->mLastOverElement == aContent) return;
+
+  // Remember mLastOverElement as the related content for the
+  // DispatchMouseOrPointerEvent() call below, since NotifyMouseOut() resets it,
+  // bug 298477.
+  nsCOMPtr<nsIContent> lastOverElement = wrapper->mLastOverElement;
+
+  bool isPointer = aMouseEvent->mClass == ePointerEventClass;
+
+  EnterLeaveDispatcher enterDispatcher(this, aContent, lastOverElement,
+                                       aMouseEvent,
+                                       isPointer ? ePointerEnter : eMouseEnter);
+
+  if (!isPointer) {
+    SetContentState(aContent, ElementState::HOVER);
+  }
+
+  NotifyMouseOut(aMouseEvent, aContent);
+
+  // Store the first mouseOver event we fire and don't refire mouseOver
+  // to that element while the first mouseOver is still ongoing.
+  wrapper->mFirstOverEventElement = aContent;
+
+  // Fire mouseover
+  wrapper->mLastOverFrame = DispatchMouseOrPointerEvent(
+      aMouseEvent, isPointer ? ePointerOver : eMouseOver, aContent,
+      lastOverElement);
+  enterDispatcher.Dispatch();
+  wrapper->mLastOverElement = aContent;
+
+  // Turn recursion protection back off
+  wrapper->mFirstOverEventElement = nullptr;
+}
+
+// Returns the center point of the window's client area. This is
+// in widget coordinates, i.e. relative to the widget's top-left
+// corner, not in screen coordinates, the same units that UIEvent::
+// refpoint is in. It may not be the exact center of the window if
+// the platform requires rounding the coordinate.
+static LayoutDeviceIntPoint GetWindowClientRectCenter(nsIWidget* aWidget) {
+  NS_ENSURE_TRUE(aWidget, LayoutDeviceIntPoint(0, 0));
+
+  LayoutDeviceIntRect rect = aWidget->GetClientBounds();
+  LayoutDeviceIntPoint point(rect.x + rect.width / 2, rect.y + rect.height / 2);
+  int32_t round = aWidget->RoundsWidgetCoordinatesTo();
+  point.x = point.x / round * round;
+  point.y = point.y / round * round;
+  return point - aWidget->WidgetToScreenOffset();
+}
+
+void EventStateManager::GeneratePointerEnterExit(EventMessage aMessage,
+                                                 WidgetMouseEvent* aEvent) {
+  WidgetPointerEvent pointerEvent(*aEvent);
+  pointerEvent.mMessage = aMessage;
+  GenerateMouseEnterExit(&pointerEvent);
+}
+
+/* static */
+void EventStateManager::UpdateLastRefPointOfMouseEvent(
+    WidgetMouseEvent* aMouseEvent) {
+  if (aMouseEvent->mMessage != eMouseMove &&
+      aMouseEvent->mMessage != ePointerMove) {
+    return;
+  }
+
+  // Mouse movement is reported on the MouseEvent.movement{X,Y} fields.
+  // Movement is calculated in UIEvent::GetMovementPoint() as:
+  //   previous_mousemove_mRefPoint - current_mousemove_mRefPoint.
+  if (PointerLockManager::IsLocked() && aMouseEvent->mWidget) {
+    // The pointer is locked. If the pointer is not located at the center of
+    // the window, dispatch a synthetic mousemove to return the pointer there.
+    // Doing this between "real" pointer moves gives the impression that the
+    // (locked) pointer can continue moving and won't stop at the screen
+    // boundary. We cancel the synthetic event so that we don't end up
+    // dispatching the centering move event to content.
+    aMouseEvent->mLastRefPoint =
+        GetWindowClientRectCenter(aMouseEvent->mWidget);
+
+  } else if (sLastRefPoint == kInvalidRefPoint) {
+    // We don't have a valid previous mousemove mRefPoint. This is either
+    // the first move we've encountered, or the mouse has just re-entered
+    // the application window. We should report (0,0) movement for this
+    // case, so make the current and previous mRefPoints the same.
+    aMouseEvent->mLastRefPoint = aMouseEvent->mRefPoint;
+  } else {
+    aMouseEvent->mLastRefPoint = sLastRefPoint;
+  }
+}
+
+/* static */
+void EventStateManager::ResetPointerToWindowCenterWhilePointerLocked(
+    WidgetMouseEvent* aMouseEvent) {
+  MOZ_ASSERT(PointerLockManager::IsLocked());
+  if ((aMouseEvent->mMessage != eMouseMove &&
+       aMouseEvent->mMessage != ePointerMove) ||
+      !aMouseEvent->mWidget) {
+    return;
+  }
+
+  // We generate pointermove from mousemove event, so only synthesize native
+  // mouse move and update sSynthCenteringPoint by mousemove event.
+  bool updateSynthCenteringPoint = aMouseEvent->mMessage == eMouseMove;
+
+  // The pointer is locked. If the pointer is not located at the center of
+  // the window, dispatch a synthetic mousemove to return the pointer there.
+  // Doing this between "real" pointer moves gives the impression that the
+  // (locked) pointer can continue moving and won't stop at the screen
+  // boundary. We cancel the synthetic event so that we don't end up
+  // dispatching the centering move event to content.
+  LayoutDeviceIntPoint center = GetWindowClientRectCenter(aMouseEvent->mWidget);
+
+  if (aMouseEvent->mRefPoint != center && updateSynthCenteringPoint) {
+    // Mouse move doesn't finish at the center of the window. Dispatch a
+    // synthetic native mouse event to move the pointer back to the center
+    // of the window, to faciliate more movement. But first, record that
+    // we've dispatched a synthetic mouse movement, so we can cancel it
+    // in the other branch here.
+    sSynthCenteringPoint = center;
+    // XXX Once we fix XXX comments in SetPointerLock about this API, we could
+    //     restrict that this API works only in the automation mode or in the
+    //     pointer locked situation.
+    aMouseEvent->mWidget->SynthesizeNativeMouseMove(
+        center + aMouseEvent->mWidget->WidgetToScreenOffset(), nullptr);
+  } else if (aMouseEvent->mRefPoint == sSynthCenteringPoint) {
+    // This is the "synthetic native" event we dispatched to re-center the
+    // pointer. Cancel it so we don't expose the centering move to content.
+    aMouseEvent->StopPropagation();
+    // Clear sSynthCenteringPoint so we don't cancel other events
+    // targeted at the center.
+    if (updateSynthCenteringPoint) {
+      sSynthCenteringPoint = kInvalidRefPoint;
+    }
+  }
+}
+
+/* static */
+void EventStateManager::UpdateLastPointerPosition(
+    WidgetMouseEvent* aMouseEvent) {
+  if (aMouseEvent->mMessage != eMouseMove) {
+    return;
+  }
+  sLastRefPoint = aMouseEvent->mRefPoint;
+}
+
+void EventStateManager::GenerateMouseEnterExit(WidgetMouseEvent* aMouseEvent) {
+  EnsureDocument(mPresContext);
+  if (!mDocument) return;
+
+  // Hold onto old target content through the event and reset after.
+  nsCOMPtr<nsIContent> targetBeforeEvent = mCurrentTargetContent;
+
+  switch (aMouseEvent->mMessage) {
+    case eMouseMove:
+    case ePointerMove:
+    case ePointerDown:
+    case ePointerGotCapture: {
+      // Get the target content target (mousemove target == mouseover target)
+      nsCOMPtr<nsIContent> targetElement = GetEventTargetContent(aMouseEvent);
+      if (!targetElement) {
+        // We're always over the document root, even if we're only
+        // over dead space in a page (whose frame is not associated with
+        // any content) or in print preview dead space
+        targetElement = mDocument->GetRootElement();
+      }
+      if (targetElement) {
+        NotifyMouseOver(aMouseEvent, targetElement);
+      }
+    } break;
+    case ePointerUp: {
+      // Get the target content target (mousemove target == mouseover target)
+      nsCOMPtr<nsIContent> targetElement = GetEventTargetContent(aMouseEvent);
+      if (!targetElement) {
+        // We're always over the document root, even if we're only
+        // over dead space in a page (whose frame is not associated with
+        // any content) or in print preview dead space
+        targetElement = mDocument->GetRootElement();
+      }
+      if (targetElement) {
+        RefPtr<OverOutElementsWrapper> helper =
+            GetWrapperByEventID(aMouseEvent);
+        if (helper) {
+          helper->mLastOverElement = targetElement;
+        }
+        NotifyMouseOut(aMouseEvent, nullptr);
+      }
+    } break;
+    case ePointerLeave:
+    case ePointerCancel:
+    case eMouseExitFromWidget: {
+      // This is actually the window mouse exit or pointer leave event. We're
+      // not moving into any new element.
+
+      RefPtr<OverOutElementsWrapper> helper = GetWrapperByEventID(aMouseEvent);
+      if (helper && helper->mLastOverFrame &&
+          nsContentUtils::GetTopLevelWidget(aMouseEvent->mWidget) !=
+              nsContentUtils::GetTopLevelWidget(
+                  helper->mLastOverFrame->GetNearestWidget())) {
+        // the Mouse/PointerOut event widget doesn't have same top widget with
+        // mLastOverFrame, it's a spurious event for mLastOverFrame
+        break;
+      }
+
+      // Reset sLastRefPoint, so that we'll know not to report any
+      // movement the next time we re-enter the window.
+      sLastRefPoint = kInvalidRefPoint;
+
+      NotifyMouseOut(aMouseEvent, nullptr);
+    } break;
+    default:
+      break;
+  }
+
+  // reset mCurretTargetContent to what it was
+  mCurrentTargetContent = targetBeforeEvent;
+}
+
+OverOutElementsWrapper* EventStateManager::GetWrapperByEventID(
+    WidgetMouseEvent* aEvent) {
+  WidgetPointerEvent* pointer = aEvent->AsPointerEvent();
+  if (!pointer) {
+    MOZ_ASSERT(aEvent->AsMouseEvent() != nullptr);
+    if (!mMouseEnterLeaveHelper) {
+      mMouseEnterLeaveHelper = new OverOutElementsWrapper();
+    }
+    return mMouseEnterLeaveHelper;
+  }
+  return mPointersEnterLeaveHelper.GetOrInsertNew(pointer->pointerId);
+}
+
+/* static */
+void EventStateManager::SetPointerLock(nsIWidget* aWidget,
+                                       nsIContent* aElement) {
+  // Reset mouse wheel transaction
+  WheelTransaction::EndTransaction();
+
+  // Deal with DnD events
+  nsCOMPtr<nsIDragService> dragService =
+      do_GetService("@mozilla.org/widget/dragservice;1");
+
+  if (PointerLockManager::IsLocked()) {
+    MOZ_ASSERT(aWidget, "Locking pointer requires a widget");
+
+    // Release all pointer capture when a pointer lock is successfully applied
+    // on an element.
+    PointerEventHandler::ReleaseAllPointerCapture();
+
+    // Store the last known ref point so we can reposition the pointer after
+    // unlock.
+    sPreLockPoint = sLastRefPoint;
+
+    // Fire a synthetic mouse move to ensure event state is updated. We first
+    // set the mouse to the center of the window, so that the mouse event
+    // doesn't report any movement.
+    // XXX Cannot we do synthesize the native mousemove in the parent process
+    //     with calling LockNativePointer below?  Then, we could make this API
+    //     work only in the automation mode.
+    sLastRefPoint = GetWindowClientRectCenter(aWidget);
+    aWidget->SynthesizeNativeMouseMove(
+        sLastRefPoint + aWidget->WidgetToScreenOffset(), nullptr);
+
+    // Suppress DnD
+    if (dragService) {
+      dragService->Suppress();
+    }
+
+    // Activate native pointer lock on platforms where it is required (Wayland)
+    aWidget->LockNativePointer();
+  } else {
+    if (aWidget) {
+      // Deactivate native pointer lock on platforms where it is required
+      aWidget->UnlockNativePointer();
+    }
+
+    // Unlocking, so return pointer to the original position by firing a
+    // synthetic mouse event. We first reset sLastRefPoint to its
+    // pre-pointerlock position, so that the synthetic mouse event reports
+    // no movement.
+    sLastRefPoint = sPreLockPoint;
+    // Reset SynthCenteringPoint to invalid so that next time we start
+    // locking pointer, it has its initial value.
+    sSynthCenteringPoint = kInvalidRefPoint;
+    if (aWidget) {
+      // XXX Cannot we do synthesize the native mousemove in the parent process
+      //     with calling `UnlockNativePointer` above?  Then, we could make this
+      //     API work only in the automation mode.
+      aWidget->SynthesizeNativeMouseMove(
+          sPreLockPoint + aWidget->WidgetToScreenOffset(), nullptr);
+    }
+
+    // Unsuppress DnD
+    if (dragService) {
+      dragService->Unsuppress();
+    }
+  }
+}
+
+void EventStateManager::GenerateDragDropEnterExit(nsPresContext* aPresContext,
+                                                  WidgetDragEvent* aDragEvent) {
+  // Hold onto old target content through the event and reset after.
+  nsCOMPtr<nsIContent> targetBeforeEvent = mCurrentTargetContent;
+
+  switch (aDragEvent->mMessage) {
+    case eDragOver: {
+      // when dragging from one frame to another, events are fired in the
+      // order: dragexit, dragenter, dragleave
+      if (sLastDragOverFrame != mCurrentTarget) {
+        // We'll need the content, too, to check if it changed separately from
+        // the frames.
+        nsCOMPtr<nsIContent> lastContent;
+        nsCOMPtr<nsIContent> targetContent;
+        mCurrentTarget->GetContentForEvent(aDragEvent,
+                                           getter_AddRefs(targetContent));
+        if (targetContent && targetContent->IsText()) {
+          targetContent = targetContent->GetFlattenedTreeParent();
+        }
+
+        if (sLastDragOverFrame) {
+          // The frame has changed but the content may not have. Check before
+          // dispatching to content
+          sLastDragOverFrame->GetContentForEvent(aDragEvent,
+                                                 getter_AddRefs(lastContent));
+          if (lastContent && lastContent->IsText()) {
+            lastContent = lastContent->GetFlattenedTreeParent();
+          }
+
+          RefPtr<nsPresContext> presContext = sLastDragOverFrame->PresContext();
+          FireDragEnterOrExit(presContext, aDragEvent, eDragExit, targetContent,
+                              lastContent, sLastDragOverFrame);
+          nsIContent* target = sLastDragOverFrame
+                                   ? sLastDragOverFrame.GetFrame()->GetContent()
+                                   : nullptr;
+          // XXXedgar, look like we need to consider fission OOP iframe, too.
+          if (IsTopLevelRemoteTarget(target)) {
+            // Dragging something and moving from web content to chrome only
+            // fires dragexit and dragleave to xul:browser. We have to forward
+            // dragexit to sLastDragOverFrame when its content is a remote
+            // target. We don't forward dragleave since it's generated from
+            // dragexit.
+            WidgetDragEvent remoteEvent(aDragEvent->IsTrusted(), eDragExit,
+                                        aDragEvent->mWidget);
+            remoteEvent.AssignDragEventData(*aDragEvent, true);
+            remoteEvent.mFlags.mIsSynthesizedForTests =
+                aDragEvent->mFlags.mIsSynthesizedForTests;
+            nsEventStatus remoteStatus = nsEventStatus_eIgnore;
+            HandleCrossProcessEvent(&remoteEvent, &remoteStatus);
+          }
+        }
+
+        AutoWeakFrame currentTraget = mCurrentTarget;
+        FireDragEnterOrExit(aPresContext, aDragEvent, eDragEnter, lastContent,
+                            targetContent, currentTraget);
+
+        if (sLastDragOverFrame) {
+          RefPtr<nsPresContext> presContext = sLastDragOverFrame->PresContext();
+          FireDragEnterOrExit(presContext, aDragEvent, eDragLeave,
+                              targetContent, lastContent, sLastDragOverFrame);
+        }
+
+        sLastDragOverFrame = mCurrentTarget;
+      }
+    } break;
+
+    case eDragExit: {
+      // This is actually the window mouse exit event.
+      if (sLastDragOverFrame) {
+        nsCOMPtr<nsIContent> lastContent;
+        sLastDragOverFrame->GetContentForEvent(aDragEvent,
+                                               getter_AddRefs(lastContent));
+
+        RefPtr<nsPresContext> lastDragOverFramePresContext =
+            sLastDragOverFrame->PresContext();
+        FireDragEnterOrExit(lastDragOverFramePresContext, aDragEvent, eDragExit,
+                            nullptr, lastContent, sLastDragOverFrame);
+        FireDragEnterOrExit(lastDragOverFramePresContext, aDragEvent,
+                            eDragLeave, nullptr, lastContent,
+                            sLastDragOverFrame);
+
+        sLastDragOverFrame = nullptr;
+      }
+    } break;
+
+    default:
+      break;
+  }
+
+  // reset mCurretTargetContent to what it was
+  mCurrentTargetContent = targetBeforeEvent;
+
+  // Now flush all pending notifications, for better responsiveness.
+  FlushLayout(aPresContext);
+}
+
+void EventStateManager::FireDragEnterOrExit(nsPresContext* aPresContext,
+                                            WidgetDragEvent* aDragEvent,
+                                            EventMessage aMessage,
+                                            nsIContent* aRelatedTarget,
+                                            nsIContent* aTargetContent,
+                                            AutoWeakFrame& aTargetFrame) {
+  MOZ_ASSERT(aMessage == eDragLeave || aMessage == eDragExit ||
+             aMessage == eDragEnter);
+  nsEventStatus status = nsEventStatus_eIgnore;
+  WidgetDragEvent event(aDragEvent->IsTrusted(), aMessage, aDragEvent->mWidget);
+  event.AssignDragEventData(*aDragEvent, false);
+  event.mFlags.mIsSynthesizedForTests =
+      aDragEvent->mFlags.mIsSynthesizedForTests;
+  event.mRelatedTarget = aRelatedTarget;
+  if (aMessage == eDragExit && !StaticPrefs::dom_event_dragexit_enabled()) {
+    event.mFlags.mOnlyChromeDispatch = true;
+  }
+
+  mCurrentTargetContent = aTargetContent;
+
+  if (aTargetContent != aRelatedTarget) {
+    // XXX This event should still go somewhere!!
+    if (aTargetContent) {
+      EventDispatcher::Dispatch(aTargetContent, aPresContext, &event, nullptr,
+                                &status);
+    }
+
+    // adjust the drag hover if the dragenter event was cancelled or this is a
+    // drag exit
+    if (status == nsEventStatus_eConsumeNoDefault || aMessage == eDragExit) {
+      SetContentState((aMessage == eDragEnter) ? aTargetContent : nullptr,
+                      ElementState::DRAGOVER);
+    }
+
+    // collect any changes to moz cursor settings stored in the event's
+    // data transfer.
+    UpdateDragDataTransfer(&event);
+  }
+
+  // Finally dispatch the event to the frame
+  if (aTargetFrame) {
+    aTargetFrame->HandleEvent(aPresContext, &event, &status);
+  }
+}
+
+void EventStateManager::UpdateDragDataTransfer(WidgetDragEvent* dragEvent) {
+  NS_ASSERTION(dragEvent, "drag event is null in UpdateDragDataTransfer!");
+  if (!dragEvent->mDataTransfer) {
+    return;
+  }
+
+  nsCOMPtr<nsIDragSession> dragSession = nsContentUtils::GetDragSession();
+
+  if (dragSession) {
+    // the initial dataTransfer is the one from the dragstart event that
+    // was set on the dragSession when the drag began.
+    RefPtr<DataTransfer> initialDataTransfer = dragSession->GetDataTransfer();
+    if (initialDataTransfer) {
+      // retrieve the current moz cursor setting and save it.
+      nsAutoString mozCursor;
+      dragEvent->mDataTransfer->GetMozCursor(mozCursor);
+      initialDataTransfer->SetMozCursor(mozCursor);
+    }
+  }
+}
+
+nsresult EventStateManager::SetClickCount(WidgetMouseEvent* aEvent,
+                                          nsEventStatus* aStatus,
+                                          nsIContent* aOverrideClickTarget) {
+  nsCOMPtr<nsIContent> mouseContent = aOverrideClickTarget;
+  if (!mouseContent && mCurrentTarget) {
+    mCurrentTarget->GetContentForEvent(aEvent, getter_AddRefs(mouseContent));
+  }
+  if (mouseContent && mouseContent->IsText()) {
+    nsINode* parent = mouseContent->GetFlattenedTreeParentNode();
+    if (parent && parent->IsContent()) {
+      mouseContent = parent->AsContent();
+    }
+  }
+
+  switch (aEvent->mButton) {
+    case MouseButton::ePrimary:
+      if (aEvent->mMessage == eMouseDown) {
+        mLastLeftMouseDownContent =
+            !aEvent->mClickEventPrevented ? mouseContent : nullptr;
+      } else if (aEvent->mMessage == eMouseUp) {
+        aEvent->mClickTarget =
+            !aEvent->mClickEventPrevented
+                ? nsContentUtils::GetCommonAncestorUnderInteractiveContent(
+                      mouseContent, mLastLeftMouseDownContent)
+                : nullptr;
+        if (aEvent->mClickTarget) {
+          aEvent->mClickCount = mLClickCount;
+          mLClickCount = 0;
+        } else {
+          aEvent->mClickCount = 0;
+        }
+        mLastLeftMouseDownContent = nullptr;
+      }
+      break;
+
+    case MouseButton::eMiddle:
+      if (aEvent->mMessage == eMouseDown) {
+        mLastMiddleMouseDownContent =
+            !aEvent->mClickEventPrevented ? mouseContent : nullptr;
+      } else if (aEvent->mMessage == eMouseUp) {
+        aEvent->mClickTarget =
+            !aEvent->mClickEventPrevented
+                ? nsContentUtils::GetCommonAncestorUnderInteractiveContent(
+                      mouseContent, mLastMiddleMouseDownContent)
+                : nullptr;
+        if (aEvent->mClickTarget) {
+          aEvent->mClickCount = mMClickCount;
+          mMClickCount = 0;
+        } else {
+          aEvent->mClickCount = 0;
+        }
+        mLastMiddleMouseDownContent = nullptr;
+      }
+      break;
+
+    case MouseButton::eSecondary:
+      if (aEvent->mMessage == eMouseDown) {
+        mLastRightMouseDownContent =
+            !aEvent->mClickEventPrevented ? mouseContent : nullptr;
+      } else if (aEvent->mMessage == eMouseUp) {
+        aEvent->mClickTarget =
+            !aEvent->mClickEventPrevented
+                ? nsContentUtils::GetCommonAncestorUnderInteractiveContent(
+                      mouseContent, mLastRightMouseDownContent)
+                : nullptr;
+        if (aEvent->mClickTarget) {
+          aEvent->mClickCount = mRClickCount;
+          mRClickCount = 0;
+        } else {
+          aEvent->mClickCount = 0;
+        }
+        mLastRightMouseDownContent = nullptr;
+      }
+      break;
+  }
+
+  return NS_OK;
+}
+
+// static
+bool EventStateManager::EventCausesClickEvents(
+    const WidgetMouseEvent& aMouseEvent) {
+  if (NS_WARN_IF(aMouseEvent.mMessage != eMouseUp)) {
+    return false;
+  }
+  // If the mouseup event is synthesized event, we don't need to dispatch
+  // click events.
+  if (!aMouseEvent.IsReal()) {
+    return false;
+  }
+  // If mouse is still over same element, clickcount will be > 1.
+  // If it has moved it will be zero, so no click.
+  if (!aMouseEvent.mClickCount || !aMouseEvent.mClickTarget) {
+    return false;
+  }
+  // If click event was explicitly prevented, we shouldn't dispatch it.
+  if (aMouseEvent.mClickEventPrevented) {
+    return false;
+  }
+  // Check that the window isn't disabled before firing a click
+  // (see bug 366544).
+  return !(aMouseEvent.mWidget && !aMouseEvent.mWidget->IsEnabled());
+}
+
+nsresult EventStateManager::InitAndDispatchClickEvent(
+    WidgetMouseEvent* aMouseUpEvent, nsEventStatus* aStatus,
+    EventMessage aMessage, PresShell* aPresShell, nsIContent* aMouseUpContent,
+    AutoWeakFrame aCurrentTarget, bool aNoContentDispatch,
+    nsIContent* aOverrideClickTarget) {
+  MOZ_ASSERT(aMouseUpEvent);
+  MOZ_ASSERT(EventCausesClickEvents(*aMouseUpEvent));
+  MOZ_ASSERT(aMouseUpContent || aCurrentTarget || aOverrideClickTarget);
+
+  WidgetMouseEvent event(aMouseUpEvent->IsTrusted(), aMessage,
+                         aMouseUpEvent->mWidget, WidgetMouseEvent::eReal);
+
+  event.mRefPoint = aMouseUpEvent->mRefPoint;
+  event.mClickCount = aMouseUpEvent->mClickCount;
+  event.mModifiers = aMouseUpEvent->mModifiers;
+  event.mButtons = aMouseUpEvent->mButtons;
+  event.mTimeStamp = aMouseUpEvent->mTimeStamp;
+  event.mFlags.mOnlyChromeDispatch =
+      aNoContentDispatch && !aMouseUpEvent->mUseLegacyNonPrimaryDispatch;
+  event.mFlags.mNoContentDispatch = aNoContentDispatch;
+  event.mButton = aMouseUpEvent->mButton;
+  event.pointerId = aMouseUpEvent->pointerId;
+  event.mInputSource = aMouseUpEvent->mInputSource;
+  nsIContent* target = aMouseUpContent;
+  nsIFrame* targetFrame = aCurrentTarget;
+  if (aOverrideClickTarget) {
+    target = aOverrideClickTarget;
+    targetFrame = aOverrideClickTarget->GetPrimaryFrame();
+  }
+
+  if (!target->IsInComposedDoc()) {
+    return NS_OK;
+  }
+
+  // Use local event status for each click event dispatching since it'll be
+  // cleared by EventStateManager::PreHandleEvent().  Therefore, dispatching
+  // an event means that previous event status will be ignored.
+  nsEventStatus status = nsEventStatus_eIgnore;
+  nsresult rv = aPresShell->HandleEventWithTarget(
+      &event, targetFrame, MOZ_KnownLive(target), &status);
+
+  // Copy mMultipleActionsPrevented flag from a click event to the mouseup
+  // event only when it's set to true.  It may be set to true if an editor has
+  // already handled it.  This is important to avoid two or more default
+  // actions handled here.
+  aMouseUpEvent->mFlags.mMultipleActionsPrevented |=
+      event.mFlags.mMultipleActionsPrevented;
+  // If current status is nsEventStatus_eConsumeNoDefault, we don't need to
+  // overwrite it.
+  if (*aStatus == nsEventStatus_eConsumeNoDefault) {
+    return rv;
+  }
+  // If new status is nsEventStatus_eConsumeNoDefault or
+  // nsEventStatus_eConsumeDoDefault, use it.
+  if (status == nsEventStatus_eConsumeNoDefault ||
+      status == nsEventStatus_eConsumeDoDefault) {
+    *aStatus = status;
+    return rv;
+  }
+  // Otherwise, keep the original status.
+  return rv;
+}
+
+nsresult EventStateManager::PostHandleMouseUp(
+    WidgetMouseEvent* aMouseUpEvent, nsEventStatus* aStatus,
+    nsIContent* aOverrideClickTarget) {
+  MOZ_ASSERT(aMouseUpEvent);
+  MOZ_ASSERT(EventCausesClickEvents(*aMouseUpEvent));
+  MOZ_ASSERT(aStatus);
+
+  RefPtr<PresShell> presShell = mPresContext->GetPresShell();
+  if (!presShell) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIContent> clickTarget =
+      nsIContent::FromEventTargetOrNull(aMouseUpEvent->mClickTarget);
+  NS_ENSURE_STATE(clickTarget);
+
+  // Fire click events if the event target is still available.
+  // Note that do not include the eMouseUp event's status since we ignore it
+  // for compatibility with the other browsers.
+  nsEventStatus status = nsEventStatus_eIgnore;
+  nsresult rv = DispatchClickEvents(presShell, aMouseUpEvent, &status,
+                                    clickTarget, aOverrideClickTarget);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Do not do anything if preceding click events are consumed.
+  // Note that Chromium dispatches "paste" event and actually pates clipboard
+  // text into focused editor even if the preceding click events are consumed.
+  // However, this is different from our traditional behavior and does not
+  // conform to DOM events.  If we need to keep compatibility with Chromium,
+  // we should change it later.
+  if (status == nsEventStatus_eConsumeNoDefault) {
+    *aStatus = nsEventStatus_eConsumeNoDefault;
+    return NS_OK;
+  }
+
+  // Handle middle click paste if it's enabled and the mouse button is middle.
+  if (aMouseUpEvent->mButton != MouseButton::eMiddle ||
+      !WidgetMouseEvent::IsMiddleClickPasteEnabled()) {
+    return NS_OK;
+  }
+  DebugOnly<nsresult> rvIgnored =
+      HandleMiddleClickPaste(presShell, aMouseUpEvent, &status, nullptr);
+  NS_WARNING_ASSERTION(NS_SUCCEEDED(rvIgnored),
+                       "Failed to paste for a middle click");
+
+  // If new status is nsEventStatus_eConsumeNoDefault or
+  // nsEventStatus_eConsumeDoDefault, use it.
+  if (*aStatus != nsEventStatus_eConsumeNoDefault &&
+      (status == nsEventStatus_eConsumeNoDefault ||
+       status == nsEventStatus_eConsumeDoDefault)) {
+    *aStatus = status;
+  }
+
+  // Don't return error even if middle mouse paste fails since we haven't
+  // handled it here.
+  return NS_OK;
+}
+
+nsresult EventStateManager::DispatchClickEvents(
+    PresShell* aPresShell, WidgetMouseEvent* aMouseUpEvent,
+    nsEventStatus* aStatus, nsIContent* aClickTarget,
+    nsIContent* aOverrideClickTarget) {
+  MOZ_ASSERT(aPresShell);
+  MOZ_ASSERT(aMouseUpEvent);
+  MOZ_ASSERT(EventCausesClickEvents(*aMouseUpEvent));
+  MOZ_ASSERT(aStatus);
+  MOZ_ASSERT(aClickTarget || aOverrideClickTarget);
+
+  bool notDispatchToContents =
+      (aMouseUpEvent->mButton == MouseButton::eMiddle ||
+       aMouseUpEvent->mButton == MouseButton::eSecondary);
+
+  bool fireAuxClick = notDispatchToContents;
+
+  AutoWeakFrame currentTarget = aClickTarget->GetPrimaryFrame();
+  nsresult rv = InitAndDispatchClickEvent(
+      aMouseUpEvent, aStatus, eMouseClick, aPresShell, aClickTarget,
+      currentTarget, notDispatchToContents, aOverrideClickTarget);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Fire auxclick event if necessary.
+  if (fireAuxClick && *aStatus != nsEventStatus_eConsumeNoDefault &&
+      aClickTarget && aClickTarget->IsInComposedDoc()) {
+    rv = InitAndDispatchClickEvent(aMouseUpEvent, aStatus, eMouseAuxClick,
+                                   aPresShell, aClickTarget, currentTarget,
+                                   false, aOverrideClickTarget);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Failed to dispatch eMouseAuxClick");
+  }
+
+  // Fire double click event if click count is 2.
+  if (aMouseUpEvent->mClickCount == 2 && !fireAuxClick && aClickTarget &&
+      aClickTarget->IsInComposedDoc()) {
+    rv = InitAndDispatchClickEvent(aMouseUpEvent, aStatus, eMouseDoubleClick,
+                                   aPresShell, aClickTarget, currentTarget,
+                                   notDispatchToContents, aOverrideClickTarget);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  return rv;
+}
+
+nsresult EventStateManager::HandleMiddleClickPaste(
+    PresShell* aPresShell, WidgetMouseEvent* aMouseEvent,
+    nsEventStatus* aStatus, EditorBase* aEditorBase) {
+  MOZ_ASSERT(aPresShell);
+  MOZ_ASSERT(aMouseEvent);
+  MOZ_ASSERT((aMouseEvent->mMessage == eMouseAuxClick &&
+              aMouseEvent->mButton == MouseButton::eMiddle) ||
+             EventCausesClickEvents(*aMouseEvent));
+  MOZ_ASSERT(aStatus);
+  MOZ_ASSERT(*aStatus != nsEventStatus_eConsumeNoDefault);
+
+  // Even if we're called twice or more for a mouse operation, we should
+  // handle only once.  Although mMultipleActionsPrevented may be set to
+  // true by different event handler in the future, we can use it for now.
+  if (aMouseEvent->mFlags.mMultipleActionsPrevented) {
+    return NS_OK;
+  }
+  aMouseEvent->mFlags.mMultipleActionsPrevented = true;
+
+  RefPtr<Selection> selection;
+  if (aEditorBase) {
+    selection = aEditorBase->GetSelection();
+    if (NS_WARN_IF(!selection)) {
+      return NS_ERROR_FAILURE;
+    }
+  } else {
+    Document* document = aPresShell->GetDocument();
+    if (NS_WARN_IF(!document)) {
+      return NS_ERROR_FAILURE;
+    }
+    selection = nsCopySupport::GetSelectionForCopy(document);
+    if (NS_WARN_IF(!selection)) {
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  // Don't modify selection here because we've already set caret to the point
+  // at "mousedown" event.
+
+  int32_t clipboardType = nsIClipboard::kGlobalClipboard;
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIClipboard> clipboardService =
+      do_GetService("@mozilla.org/widget/clipboard;1", &rv);
+  if (NS_SUCCEEDED(rv)) {
+    bool selectionSupported;
+    rv = clipboardService->SupportsSelectionClipboard(&selectionSupported);
+    if (NS_SUCCEEDED(rv) && selectionSupported) {
+      clipboardType = nsIClipboard::kSelectionClipboard;
+    }
+  }
+
+  // Fire ePaste event by ourselves since we need to dispatch "paste" event
+  // even if the middle click event was consumed for compatibility with
+  // Chromium.
+  if (!nsCopySupport::FireClipboardEvent(ePaste, clipboardType, aPresShell,
+                                         selection)) {
+    *aStatus = nsEventStatus_eConsumeNoDefault;
+    return NS_OK;
+  }
+
+  // Although we've fired "paste" event, there is no editor to accept the
+  // clipboard content.
+  if (!aEditorBase) {
+    return NS_OK;
+  }
+
+  // Check if the editor is still the good target to paste.
+  if (aEditorBase->Destroyed() || aEditorBase->IsReadonly()) {
+    // XXX Should we consume the event when the editor is readonly and/or
+    //     disabled?
+    return NS_OK;
+  }
+
+  // The selection may have been modified during reflow.  Therefore, we
+  // should adjust event target to pass IsAcceptableInputEvent().
+  const nsRange* range = selection->GetRangeAt(0);
+  if (!range) {
+    return NS_OK;
+  }
+  WidgetMouseEvent mouseEvent(*aMouseEvent);
+  mouseEvent.mOriginalTarget = range->GetStartContainer();
+  if (NS_WARN_IF(!mouseEvent.mOriginalTarget) ||
+      !aEditorBase->IsAcceptableInputEvent(&mouseEvent)) {
+    return NS_OK;
+  }
+
+  // If Control key is pressed, we should paste clipboard content as
+  // quotation.  Otherwise, paste it as is.
+  if (aMouseEvent->IsControl()) {
+    DebugOnly<nsresult> rv =
+        aEditorBase->PasteAsQuotationAsAction(clipboardType, false);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Failed to paste as quotation");
+  } else {
+    DebugOnly<nsresult> rv = aEditorBase->PasteAsAction(clipboardType, false);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Failed to paste");
+  }
+  *aStatus = nsEventStatus_eConsumeNoDefault;
+
+  return NS_OK;
+}
+
+void EventStateManager::ConsumeInteractionData(
+    Record<nsString, dom::InteractionData>& aInteractions) {
+  OnTypingInteractionEnded();
+
+  aInteractions.Entries().Clear();
+  auto newEntry = aInteractions.Entries().AppendElement();
+  newEntry->mKey = u"Typing"_ns;
+  newEntry->mValue = gTypingInteraction;
+  gTypingInteraction = {};
+}
+
+nsIFrame* EventStateManager::GetEventTarget() {
+  PresShell* presShell;
+  if (mCurrentTarget || !mPresContext ||
+      !(presShell = mPresContext->GetPresShell())) {
+    return mCurrentTarget;
+  }
+
+  if (mCurrentTargetContent) {
+    mCurrentTarget = mPresContext->GetPrimaryFrameFor(mCurrentTargetContent);
+    if (mCurrentTarget) {
+      return mCurrentTarget;
+    }
+  }
+
+  nsIFrame* frame = presShell->GetCurrentEventFrame();
+  return (mCurrentTarget = frame);
+}
+
+already_AddRefed<nsIContent> EventStateManager::GetEventTargetContent(
+    WidgetEvent* aEvent) {
+  if (aEvent && (aEvent->mMessage == eFocus || aEvent->mMessage == eBlur)) {
+    nsCOMPtr<nsIContent> content = GetFocusedElement();
+    return content.forget();
+  }
+
+  if (mCurrentTargetContent) {
+    nsCOMPtr<nsIContent> content = mCurrentTargetContent;
+    return content.forget();
+  }
+
+  nsCOMPtr<nsIContent> content;
+  if (PresShell* presShell = mPresContext->GetPresShell()) {
+    content = presShell->GetEventTargetContent(aEvent);
+  }
+
+  // Some events here may set mCurrentTarget but not set the corresponding
+  // event target in the PresShell.
+  if (!content && mCurrentTarget) {
+    mCurrentTarget->GetContentForEvent(aEvent, getter_AddRefs(content));
+  }
+
+  return content.forget();
+}
+
+static Element* GetLabelTarget(nsIContent* aPossibleLabel) {
+  mozilla::dom::HTMLLabelElement* label =
+      mozilla::dom::HTMLLabelElement::FromNode(aPossibleLabel);
+  if (!label) return nullptr;
+
+  return label->GetLabeledElement();
+}
+
+/* static */
+inline void EventStateManager::DoStateChange(Element* aElement,
+                                             ElementState aState,
+                                             bool aAddState) {
+  if (aAddState) {
+    aElement->AddStates(aState);
+  } else {
+    aElement->RemoveStates(aState);
+  }
+}
+
+/* static */
+inline void EventStateManager::DoStateChange(nsIContent* aContent,
+                                             ElementState aState,
+                                             bool aStateAdded) {
+  if (aContent->IsElement()) {
+    DoStateChange(aContent->AsElement(), aState, aStateAdded);
+  }
+}
+
+/* static */
+void EventStateManager::UpdateAncestorState(nsIContent* aStartNode,
+                                            nsIContent* aStopBefore,
+                                            ElementState aState,
+                                            bool aAddState) {
+  for (; aStartNode && aStartNode != aStopBefore;
+       aStartNode = aStartNode->GetFlattenedTreeParent()) {
+    // We might be starting with a non-element (e.g. a text node) and
+    // if someone is doing something weird might be ending with a
+    // non-element too (e.g. a document fragment)
+    if (!aStartNode->IsElement()) {
+      continue;
+    }
+    Element* element = aStartNode->AsElement();
+    DoStateChange(element, aState, aAddState);
+    Element* labelTarget = GetLabelTarget(element);
+    if (labelTarget) {
+      DoStateChange(labelTarget, aState, aAddState);
+    }
+  }
+
+  if (aAddState) {
+    // We might be in a situation where a node was in hover both
+    // because it was hovered and because the label for it was
+    // hovered, and while we stopped hovering the node the label is
+    // still hovered.  Or we might have had two nested labels for the
+    // same node, and while one is no longer hovered the other still
+    // is.  In that situation, the label that's still hovered will be
+    // aStopBefore or some ancestor of it, and the call we just made
+    // to UpdateAncestorState with aAddState = false would have
+    // removed the hover state from the node.  But the node should
+    // still be in hover state.  To handle this situation we need to
+    // keep walking up the tree and any time we find a label mark its
+    // corresponding node as still in our state.
+    for (; aStartNode; aStartNode = aStartNode->GetFlattenedTreeParent()) {
+      if (!aStartNode->IsElement()) {
+        continue;
+      }
+
+      Element* labelTarget = GetLabelTarget(aStartNode->AsElement());
+      if (labelTarget && !labelTarget->State().HasState(aState)) {
+        DoStateChange(labelTarget, aState, true);
+      }
+    }
+  }
+}
+
+// static
+bool CanContentHaveActiveState(nsIContent& aContent) {
+  // Editable content can never become active since their default actions
+  // are disabled.  Watch out for editable content in native anonymous
+  // subtrees though, as they belong to text controls.
+  return !aContent.IsEditable() || aContent.IsInNativeAnonymousSubtree();
+}
+
+bool EventStateManager::SetContentState(nsIContent* aContent,
+                                        ElementState aState) {
+  MOZ_ASSERT(ManagesState(aState), "Unexpected state");
+
+  nsCOMPtr<nsIContent> notifyContent1;
+  nsCOMPtr<nsIContent> notifyContent2;
+  bool updateAncestors;
+
+  if (aState == ElementState::HOVER || aState == ElementState::ACTIVE) {
+    // Hover and active are hierarchical
+    updateAncestors = true;
+
+    // check to see that this state is allowed by style. Check dragover too?
+    // XXX Is this even what we want?
+    if (mCurrentTarget &&
+        mCurrentTarget->StyleUI()->UserInput() == StyleUserInput::None) {
+      return false;
+    }
+
+    if (aState == ElementState::ACTIVE) {
+      if (aContent && !CanContentHaveActiveState(*aContent)) {
+        aContent = nullptr;
+      }
+      if (aContent != mActiveContent) {
+        notifyContent1 = aContent;
+        notifyContent2 = mActiveContent;
+        mActiveContent = aContent;
+      }
+    } else {
+      NS_ASSERTION(aState == ElementState::HOVER, "How did that happen?");
+      nsIContent* newHover;
+
+      if (mPresContext->IsDynamic()) {
+        newHover = aContent;
+      } else {
+        NS_ASSERTION(!aContent || aContent->GetComposedDoc() ==
+                                      mPresContext->PresShell()->GetDocument(),
+                     "Unexpected document");
+        nsIFrame* frame = aContent ? aContent->GetPrimaryFrame() : nullptr;
+        if (frame && nsLayoutUtils::IsViewportScrollbarFrame(frame)) {
+          // The scrollbars of viewport should not ignore the hover state.
+          // Because they are *not* the content of the web page.
+          newHover = aContent;
+        } else {
+          // All contents of the web page should ignore the hover state.
+          newHover = nullptr;
+        }
+      }
+
+      if (newHover != mHoverContent) {
+        notifyContent1 = newHover;
+        notifyContent2 = mHoverContent;
+        mHoverContent = newHover;
+      }
+    }
+  } else {
+    updateAncestors = false;
+    if (aState == ElementState::DRAGOVER) {
+      if (aContent != sDragOverContent) {
+        notifyContent1 = aContent;
+        notifyContent2 = sDragOverContent;
+        sDragOverContent = aContent;
+      }
+    } else if (aState == ElementState::URLTARGET) {
+      if (aContent != mURLTargetContent) {
+        notifyContent1 = aContent;
+        notifyContent2 = mURLTargetContent;
+        mURLTargetContent = aContent;
+      }
+    }
+  }
+
+  // We need to keep track of which of notifyContent1 and notifyContent2 is
+  // getting the state set and which is getting it unset.  If both are
+  // non-null, then notifyContent1 is having the state set and notifyContent2
+  // is having it unset.  But if one of them is null, we need to keep track of
+  // the right thing for notifyContent1 explicitly.
+  bool content1StateSet = true;
+  if (!notifyContent1) {
+    // This is ok because FindCommonAncestor wouldn't find anything
+    // anyway if notifyContent1 is null.
+    notifyContent1 = notifyContent2;
+    notifyContent2 = nullptr;
+    content1StateSet = false;
+  }
+
+  if (notifyContent1 && mPresContext) {
+    EnsureDocument(mPresContext);
+    if (mDocument) {
+      nsAutoScriptBlocker scriptBlocker;
+
+      if (updateAncestors) {
+        nsCOMPtr<nsIContent> commonAncestor =
+            FindCommonAncestor(notifyContent1, notifyContent2);
+        if (notifyContent2) {
+          // It's very important to first notify the state removal and
+          // then the state addition, because due to labels it's
+          // possible that we're removing state from some element but
+          // then adding it again (say because mHoverContent changed
+          // from a control to its label).
+          UpdateAncestorState(notifyContent2, commonAncestor, aState, false);
+        }
+        UpdateAncestorState(notifyContent1, commonAncestor, aState,
+                            content1StateSet);
+      } else {
+        if (notifyContent2) {
+          DoStateChange(notifyContent2, aState, false);
+        }
+        DoStateChange(notifyContent1, aState, content1StateSet);
+      }
+    }
+  }
+
+  return true;
+}
+
+void EventStateManager::ResetLastOverForContent(
+    const uint32_t& aIdx, const RefPtr<OverOutElementsWrapper>& aElemWrapper,
+    nsIContent* aContent) {
+  if (aElemWrapper && aElemWrapper->mLastOverElement &&
+      nsContentUtils::ContentIsFlattenedTreeDescendantOf(
+          aElemWrapper->mLastOverElement, aContent)) {
+    aElemWrapper->mLastOverElement = nullptr;
+  }
+}
+
+void EventStateManager::RemoveNodeFromChainIfNeeded(ElementState aState,
+                                                    nsIContent* aContentRemoved,
+                                                    bool aNotify) {
+  MOZ_ASSERT(aState == ElementState::HOVER || aState == ElementState::ACTIVE);
+  if (!aContentRemoved->IsElement() ||
+      !aContentRemoved->AsElement()->State().HasState(aState)) {
+    return;
+  }
+
+  nsCOMPtr<nsIContent>& leaf =
+      aState == ElementState::HOVER ? mHoverContent : mActiveContent;
+
+  MOZ_ASSERT(leaf);
+  // These two NS_ASSERTIONS below can fail for Shadow DOM sometimes, and it's
+  // not clear how to best handle it, see
+  // https://github.com/whatwg/html/issues/4795 and bug 1551621.
+  NS_ASSERTION(
+      nsContentUtils::ContentIsFlattenedTreeDescendantOf(leaf, aContentRemoved),
+      "Flat tree and active / hover chain got out of sync");
+
+  nsIContent* newLeaf = aContentRemoved->GetFlattenedTreeParent();
+  MOZ_ASSERT(!newLeaf || newLeaf->IsElement());
+  NS_ASSERTION(!newLeaf || newLeaf->AsElement()->State().HasState(aState),
+               "State got out of sync because of shadow DOM");
+  if (aNotify) {
+    SetContentState(newLeaf, aState);
+  } else {
+    // We don't update the removed content's state here, since removing NAC
+    // happens from layout and we don't really want to notify at that point or
+    // what not.
+    //
+    // Also, NAC is not observable and NAC being removed will go away soon.
+    leaf = newLeaf;
+  }
+  MOZ_ASSERT(leaf == newLeaf || (aState == ElementState::ACTIVE && !leaf &&
+                                 !CanContentHaveActiveState(*newLeaf)));
+}
+
+void EventStateManager::NativeAnonymousContentRemoved(nsIContent* aContent) {
+  MOZ_ASSERT(aContent->IsRootOfNativeAnonymousSubtree());
+  RemoveNodeFromChainIfNeeded(ElementState::HOVER, aContent, false);
+  RemoveNodeFromChainIfNeeded(ElementState::ACTIVE, aContent, false);
+
+  if (mLastLeftMouseDownContent &&
+      nsContentUtils::ContentIsFlattenedTreeDescendantOf(
+          mLastLeftMouseDownContent, aContent)) {
+    mLastLeftMouseDownContent = aContent->GetFlattenedTreeParent();
+  }
+
+  if (mLastMiddleMouseDownContent &&
+      nsContentUtils::ContentIsFlattenedTreeDescendantOf(
+          mLastMiddleMouseDownContent, aContent)) {
+    mLastMiddleMouseDownContent = aContent->GetFlattenedTreeParent();
+  }
+
+  if (mLastRightMouseDownContent &&
+      nsContentUtils::ContentIsFlattenedTreeDescendantOf(
+          mLastRightMouseDownContent, aContent)) {
+    mLastRightMouseDownContent = aContent->GetFlattenedTreeParent();
+  }
+}
+
+void EventStateManager::ContentRemoved(Document* aDocument,
+                                       nsIContent* aContent) {
+  /*
+   * Anchor and area elements when focused or hovered might make the UI to show
+   * the current link. We want to make sure that the UI gets informed when they
+   * are actually removed from the DOM.
+   */
+  if (aContent->IsAnyOfHTMLElements(nsGkAtoms::a, nsGkAtoms::area) &&
+      (aContent->AsElement()->State().HasAtLeastOneOfStates(
+          ElementState::FOCUS | ElementState::HOVER))) {
+    Element* element = aContent->AsElement();
+    element->LeaveLink(element->GetPresContext(Element::eForComposedDoc));
+  }
+
+  if (aContent->IsElement()) {
+    if (RefPtr<nsPresContext> presContext = mPresContext) {
+      IMEStateManager::OnRemoveContent(*presContext,
+                                       MOZ_KnownLive(*aContent->AsElement()));
+    }
+  }
+
+  // inform the focus manager that the content is being removed. If this
+  // content is focused, the focus will be removed without firing events.
+  if (RefPtr<nsFocusManager> fm = nsFocusManager::GetFocusManager()) {
+    fm->ContentRemoved(aDocument, aContent);
+  }
+
+  RemoveNodeFromChainIfNeeded(ElementState::HOVER, aContent, true);
+  RemoveNodeFromChainIfNeeded(ElementState::ACTIVE, aContent, true);
+
+  if (sDragOverContent &&
+      sDragOverContent->OwnerDoc() == aContent->OwnerDoc() &&
+      nsContentUtils::ContentIsFlattenedTreeDescendantOf(sDragOverContent,
+                                                         aContent)) {
+    sDragOverContent = nullptr;
+  }
+
+  PointerEventHandler::ReleaseIfCaptureByDescendant(aContent);
+
+  // See bug 292146 for why we want to null this out
+  ResetLastOverForContent(0, mMouseEnterLeaveHelper, aContent);
+  for (const auto& entry : mPointersEnterLeaveHelper) {
+    ResetLastOverForContent(entry.GetKey(), entry.GetData(), aContent);
+  }
+}
+
+void EventStateManager::TextControlRootWillBeRemoved(
+    TextControlElement& aTextControlElement) {
+  if (!mGestureDownInTextControl || !mGestureDownFrameOwner ||
+      !mGestureDownFrameOwner->IsInNativeAnonymousSubtree()) {
+    return;
+  }
+  // If we track gesture to start drag in aTextControlElement, we should keep
+  // tracking it with aTextContrlElement itself for now because this may be
+  // caused by reframing aTextControlElement which may not be intended by the
+  // user.
+  if (&aTextControlElement ==
+      mGestureDownFrameOwner->GetClosestNativeAnonymousSubtreeRootParent()) {
+    mGestureDownFrameOwner = &aTextControlElement;
+  }
+}
+
+void EventStateManager::TextControlRootAdded(
+    Element& aAnonymousDivElement, TextControlElement& aTextControlElement) {
+  if (!mGestureDownInTextControl ||
+      mGestureDownFrameOwner != &aTextControlElement) {
+    return;
+  }
+  // If we track gesture to start drag in aTextControlElement, but the frame
+  // owner is the text control element itself, the anonymous nodes in it are
+  // recreated by a reframe.  If so, we should keep tracking it with the
+  // recreated native anonymous node.
+  mGestureDownFrameOwner =
+      aAnonymousDivElement.GetFirstChild()
+          ? aAnonymousDivElement.GetFirstChild()
+          : static_cast<nsIContent*>(&aAnonymousDivElement);
+}
+
+bool EventStateManager::EventStatusOK(WidgetGUIEvent* aEvent) {
+  return !(aEvent->mMessage == eMouseDown &&
+           aEvent->AsMouseEvent()->mButton == MouseButton::ePrimary &&
+           !sNormalLMouseEventInProcess);
+}
+
+//-------------------------------------------
+// Access Key Registration
+//-------------------------------------------
+void EventStateManager::RegisterAccessKey(Element* aElement, uint32_t aKey) {
+  if (aElement && !mAccessKeys.Contains(aElement)) {
+    mAccessKeys.AppendObject(aElement);
+  }
+}
+
+void EventStateManager::UnregisterAccessKey(Element* aElement, uint32_t aKey) {
+  if (aElement) {
+    mAccessKeys.RemoveObject(aElement);
+  }
+}
+
+uint32_t EventStateManager::GetRegisteredAccessKey(Element* aElement) {
+  MOZ_ASSERT(aElement);
+
+  if (!mAccessKeys.Contains(aElement)) {
+    return 0;
+  }
+
+  nsAutoString accessKey;
+  aElement->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, accessKey);
+  return accessKey.First();
+}
+
+void EventStateManager::EnsureDocument(nsPresContext* aPresContext) {
+  if (!mDocument) mDocument = aPresContext->Document();
+}
+
+void EventStateManager::FlushLayout(nsPresContext* aPresContext) {
+  MOZ_ASSERT(aPresContext, "nullptr ptr");
+  if (RefPtr<PresShell> presShell = aPresContext->GetPresShell()) {
+    presShell->FlushPendingNotifications(FlushType::InterruptibleLayout);
+  }
+}
+
+Element* EventStateManager::GetFocusedElement() {
+  nsFocusManager* fm = nsFocusManager::GetFocusManager();
+  EnsureDocument(mPresContext);
+  if (!fm || !mDocument) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsPIDOMWindowOuter> focusedWindow;
+  return nsFocusManager::GetFocusedDescendant(
+      mDocument->GetWindow(), nsFocusManager::eOnlyCurrentWindow,
+      getter_AddRefs(focusedWindow));
+}
+
+//-------------------------------------------------------
+// Return true if the docshell is visible
+
+bool EventStateManager::IsShellVisible(nsIDocShell* aShell) {
+  NS_ASSERTION(aShell, "docshell is null");
+
+  nsCOMPtr<nsIBaseWindow> basewin = do_QueryInterface(aShell);
+  if (!basewin) return true;
+
+  bool isVisible = true;
+  basewin->GetVisibility(&isVisible);
+
+  // We should be doing some additional checks here so that
+  // we don't tab into hidden tabs of tabbrowser.  -bryner
+
+  return isVisible;
+}
+
+nsresult EventStateManager::DoContentCommandEvent(
+    WidgetContentCommandEvent* aEvent) {
+  EnsureDocument(mPresContext);
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_FAILURE);
+  nsCOMPtr<nsPIDOMWindowOuter> window(mDocument->GetWindow());
+  NS_ENSURE_TRUE(window, NS_ERROR_FAILURE);
+
+  nsCOMPtr<nsPIWindowRoot> root = window->GetTopWindowRoot();
+  NS_ENSURE_TRUE(root, NS_ERROR_FAILURE);
+  const char* cmd;
+  switch (aEvent->mMessage) {
+    case eContentCommandCut:
+      cmd = "cmd_cut";
+      break;
+    case eContentCommandCopy:
+      cmd = "cmd_copy";
+      break;
+    case eContentCommandPaste:
+      cmd = "cmd_paste";
+      break;
+    case eContentCommandDelete:
+      cmd = "cmd_delete";
+      break;
+    case eContentCommandUndo:
+      cmd = "cmd_undo";
+      break;
+    case eContentCommandRedo:
+      cmd = "cmd_redo";
+      break;
+    case eContentCommandPasteTransferable:
+      cmd = "cmd_pasteTransferable";
+      break;
+    case eContentCommandLookUpDictionary:
+      cmd = "cmd_lookUpDictionary";
+      break;
+    default:
+      return NS_ERROR_NOT_IMPLEMENTED;
+  }
+  // If user tries to do something, user must try to do it in visible window.
+  // So, let's retrieve controller of visible window.
+  nsCOMPtr<nsIController> controller;
+  nsresult rv =
+      root->GetControllerForCommand(cmd, true, getter_AddRefs(controller));
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (!controller) {
+    // When GetControllerForCommand succeeded but there is no controller, the
+    // command isn't supported.
+    aEvent->mIsEnabled = false;
+  } else {
+    bool canDoIt;
+    rv = controller->IsCommandEnabled(cmd, &canDoIt);
+    NS_ENSURE_SUCCESS(rv, rv);
+    aEvent->mIsEnabled = canDoIt;
+    if (canDoIt && !aEvent->mOnlyEnabledCheck) {
+      switch (aEvent->mMessage) {
+        case eContentCommandPasteTransferable: {
+          BrowserParent* remote = BrowserParent::GetFocused();
+          if (remote) {
+            nsCOMPtr<nsITransferable> transferable = aEvent->mTransferable;
+            IPCDataTransfer ipcDataTransfer;
+            nsContentUtils::TransferableToIPCTransferable(
+                transferable, &ipcDataTransfer, false, nullptr,
+                remote->Manager());
+            bool isPrivateData = transferable->GetIsPrivateData();
+            nsCOMPtr<nsIPrincipal> requestingPrincipal =
+                transferable->GetRequestingPrincipal();
+            nsContentPolicyType contentPolicyType =
+                transferable->GetContentPolicyType();
+            remote->SendPasteTransferable(std::move(ipcDataTransfer),
+                                          isPrivateData, requestingPrincipal,
+                                          contentPolicyType);
+            rv = NS_OK;
+          } else {
+            nsCOMPtr<nsICommandController> commandController =
+                do_QueryInterface(controller);
+            NS_ENSURE_STATE(commandController);
+
+            RefPtr<nsCommandParams> params = new nsCommandParams();
+            rv = params->SetISupports("transferable", aEvent->mTransferable);
+            if (NS_WARN_IF(NS_FAILED(rv))) {
+              return rv;
+            }
+            rv = commandController->DoCommandWithParams(cmd, params);
+          }
+          break;
+        }
+
+        case eContentCommandLookUpDictionary: {
+          nsCOMPtr<nsICommandController> commandController =
+              do_QueryInterface(controller);
+          if (NS_WARN_IF(!commandController)) {
+            return NS_ERROR_FAILURE;
+          }
+
+          RefPtr<nsCommandParams> params = new nsCommandParams();
+          rv = params->SetInt("x", aEvent->mRefPoint.x);
+          if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+          }
+
+          rv = params->SetInt("y", aEvent->mRefPoint.y);
+          if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+          }
+
+          rv = commandController->DoCommandWithParams(cmd, params);
+          break;
+        }
+
+        default:
+          rv = controller->DoCommand(cmd);
+          break;
+      }
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+  }
+  aEvent->mSucceeded = true;
+  return NS_OK;
+}
+
+nsresult EventStateManager::DoContentCommandInsertTextEvent(
+    WidgetContentCommandEvent* aEvent) {
+  MOZ_ASSERT(aEvent);
+  MOZ_ASSERT(aEvent->mMessage == eContentCommandInsertText);
+  MOZ_DIAGNOSTIC_ASSERT(aEvent->mString.isSome());
+  MOZ_DIAGNOSTIC_ASSERT(!aEvent->mString.ref().IsEmpty());
+
+  aEvent->mIsEnabled = false;
+  aEvent->mSucceeded = false;
+
+  NS_ENSURE_TRUE(mPresContext, NS_ERROR_NOT_AVAILABLE);
+
+  if (XRE_IsParentProcess()) {
+    // Handle it in focused content process if there is.
+    if (BrowserParent* remote = BrowserParent::GetFocused()) {
+      remote->SendInsertText(aEvent->mString.ref());
+      aEvent->mIsEnabled = true;  // XXX it can be a lie...
+      aEvent->mSucceeded = true;
+      return NS_OK;
+    }
+  }
+
+  // If there is no active editor in this process, we should treat the command
+  // is disabled.
+  RefPtr<EditorBase> activeEditor =
+      nsContentUtils::GetActiveEditor(mPresContext);
+  if (!activeEditor) {
+    aEvent->mSucceeded = true;
+    return NS_OK;
+  }
+
+  nsresult rv = activeEditor->InsertTextAsAction(aEvent->mString.ref());
+  aEvent->mIsEnabled = rv != NS_SUCCESS_DOM_NO_OPERATION;
+  aEvent->mSucceeded = NS_SUCCEEDED(rv);
+  return NS_OK;
+}
+
+nsresult EventStateManager::DoContentCommandScrollEvent(
+    WidgetContentCommandEvent* aEvent) {
+  NS_ENSURE_TRUE(mPresContext, NS_ERROR_NOT_AVAILABLE);
+  PresShell* presShell = mPresContext->GetPresShell();
+  NS_ENSURE_TRUE(presShell, NS_ERROR_NOT_AVAILABLE);
+  NS_ENSURE_TRUE(aEvent->mScroll.mAmount != 0, NS_ERROR_INVALID_ARG);
+
+  ScrollUnit scrollUnit;
+  switch (aEvent->mScroll.mUnit) {
+    case WidgetContentCommandEvent::eCmdScrollUnit_Line:
+      scrollUnit = ScrollUnit::LINES;
+      break;
+    case WidgetContentCommandEvent::eCmdScrollUnit_Page:
+      scrollUnit = ScrollUnit::PAGES;
+      break;
+    case WidgetContentCommandEvent::eCmdScrollUnit_Whole:
+      scrollUnit = ScrollUnit::WHOLE;
+      break;
+    default:
+      return NS_ERROR_INVALID_ARG;
+  }
+
+  aEvent->mSucceeded = true;
+
+  nsIScrollableFrame* sf =
+      presShell->GetScrollableFrameToScroll(layers::EitherScrollDirection);
+  aEvent->mIsEnabled =
+      sf ? (aEvent->mScroll.mIsHorizontal ? WheelHandlingUtils::CanScrollOn(
+                                                sf, aEvent->mScroll.mAmount, 0)
+                                          : WheelHandlingUtils::CanScrollOn(
+                                                sf, 0, aEvent->mScroll.mAmount))
+         : false;
+
+  if (!aEvent->mIsEnabled || aEvent->mOnlyEnabledCheck) {
+    return NS_OK;
+  }
+
+  nsIntPoint pt(0, 0);
+  if (aEvent->mScroll.mIsHorizontal) {
+    pt.x = aEvent->mScroll.mAmount;
+  } else {
+    pt.y = aEvent->mScroll.mAmount;
+  }
+
+  // The caller may want synchronous scrolling.
+  sf->ScrollBy(pt, scrollUnit, ScrollMode::Instant);
+  return NS_OK;
+}
+
+void EventStateManager::SetActiveManager(EventStateManager* aNewESM,
+                                         nsIContent* aContent) {
+  if (sActiveESM && aNewESM != sActiveESM) {
+    sActiveESM->SetContentState(nullptr, ElementState::ACTIVE);
+  }
+  sActiveESM = aNewESM;
+  if (sActiveESM && aContent) {
+    sActiveESM->SetContentState(aContent, ElementState::ACTIVE);
+  }
+}
+
+void EventStateManager::ClearGlobalActiveContent(EventStateManager* aClearer) {
+  if (aClearer) {
+    aClearer->SetContentState(nullptr, ElementState::ACTIVE);
+    if (sDragOverContent) {
+      aClearer->SetContentState(nullptr, ElementState::DRAGOVER);
+    }
+  }
+  if (sActiveESM && aClearer != sActiveESM) {
+    sActiveESM->SetContentState(nullptr, ElementState::ACTIVE);
+  }
+  sActiveESM = nullptr;
+}
+
+/******************************************************************/
+/* mozilla::EventStateManager::DeltaAccumulator                   */
+/******************************************************************/
+
+void EventStateManager::DeltaAccumulator::InitLineOrPageDelta(
+    nsIFrame* aTargetFrame, EventStateManager* aESM, WidgetWheelEvent* aEvent) {
+  MOZ_ASSERT(aESM);
+  MOZ_ASSERT(aEvent);
+
+  // Reset if the previous wheel event is too old.
+  if (!mLastTime.IsNull()) {
+    TimeDuration duration = TimeStamp::Now() - mLastTime;
+    if (duration.ToMilliseconds() >
+        StaticPrefs::mousewheel_transaction_timeout()) {
+      Reset();
+    }
+  }
+  // If we have accumulated delta,  we may need to reset it.
+  if (IsInTransaction()) {
+    // If wheel event type is changed, reset the values.
+    if (mHandlingDeltaMode != aEvent->mDeltaMode ||
+        mIsNoLineOrPageDeltaDevice != aEvent->mIsNoLineOrPageDelta) {
+      Reset();
+    } else {
+      // If the delta direction is changed, we should reset only the
+      // accumulated values.
+      if (mX && aEvent->mDeltaX && ((aEvent->mDeltaX > 0.0) != (mX > 0.0))) {
+        mX = mPendingScrollAmountX = 0.0;
+      }
+      if (mY && aEvent->mDeltaY && ((aEvent->mDeltaY > 0.0) != (mY > 0.0))) {
+        mY = mPendingScrollAmountY = 0.0;
+      }
+    }
+  }
+
+  mHandlingDeltaMode = aEvent->mDeltaMode;
+  mIsNoLineOrPageDeltaDevice = aEvent->mIsNoLineOrPageDelta;
+
+  {
+    nsIFrame* frame = aESM->ComputeScrollTarget(aTargetFrame, aEvent,
+                                                COMPUTE_DEFAULT_ACTION_TARGET);
+    nsPresContext* pc =
+        frame ? frame->PresContext() : aTargetFrame->PresContext();
+    nsIScrollableFrame* scrollTarget = do_QueryFrame(frame);
+    aEvent->mScrollAmount = aESM->GetScrollAmount(pc, aEvent, scrollTarget);
+  }
+
+  // If it's handling neither a device that does not provide line or page deltas
+  // nor delta values multiplied by prefs, we must not modify lineOrPageDelta
+  // values.
+  // TODO(emilio): Does this care about overridden scroll speed?
+  if (!mIsNoLineOrPageDeltaDevice &&
+      !EventStateManager::WheelPrefs::GetInstance()
+           ->NeedToComputeLineOrPageDelta(aEvent)) {
+    // Set the delta values to mX and mY.  They would be used when above block
+    // resets mX/mY/mPendingScrollAmountX/mPendingScrollAmountY if the direction
+    // is changed.
+    // NOTE: We shouldn't accumulate the delta values, it might could cause
+    //       overflow even though it's not a realistic situation.
+    if (aEvent->mDeltaX) {
+      mX = aEvent->mDeltaX;
+    }
+    if (aEvent->mDeltaY) {
+      mY = aEvent->mDeltaY;
+    }
+    mLastTime = TimeStamp::Now();
+    return;
+  }
+
+  mX += aEvent->mDeltaX;
+  mY += aEvent->mDeltaY;
+
+  if (mHandlingDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL) {
+    // Records pixel delta values and init mLineOrPageDeltaX and
+    // mLineOrPageDeltaY for wheel events which are caused by pixel only
+    // devices.  Ignore mouse wheel transaction for computing this.  The
+    // lineOrPageDelta values will be used by dispatching legacy
+    // eMouseScrollEventClass (DOMMouseScroll) but not be used for scrolling
+    // of default action.  The transaction should be used only for the default
+    // action.
+    auto scrollAmountInCSSPixels =
+        CSSIntSize::FromAppUnitsRounded(aEvent->mScrollAmount);
+
+    aEvent->mLineOrPageDeltaX = RoundDown(mX) / scrollAmountInCSSPixels.width;
+    aEvent->mLineOrPageDeltaY = RoundDown(mY) / scrollAmountInCSSPixels.height;
+
+    mX -= aEvent->mLineOrPageDeltaX * scrollAmountInCSSPixels.width;
+    mY -= aEvent->mLineOrPageDeltaY * scrollAmountInCSSPixels.height;
+  } else {
+    aEvent->mLineOrPageDeltaX = RoundDown(mX);
+    aEvent->mLineOrPageDeltaY = RoundDown(mY);
+    mX -= aEvent->mLineOrPageDeltaX;
+    mY -= aEvent->mLineOrPageDeltaY;
+  }
+
+  mLastTime = TimeStamp::Now();
+}
+
+void EventStateManager::DeltaAccumulator::Reset() {
+  mX = mY = 0.0;
+  mPendingScrollAmountX = mPendingScrollAmountY = 0.0;
+  mHandlingDeltaMode = UINT32_MAX;
+  mIsNoLineOrPageDeltaDevice = false;
+}
+
+nsIntPoint
+EventStateManager::DeltaAccumulator::ComputeScrollAmountForDefaultAction(
+    WidgetWheelEvent* aEvent, const nsIntSize& aScrollAmountInDevPixels) {
+  MOZ_ASSERT(aEvent);
+
+  DeltaValues acceleratedDelta = WheelTransaction::AccelerateWheelDelta(aEvent);
+
+  nsIntPoint result(0, 0);
+  if (aEvent->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL) {
+    mPendingScrollAmountX += acceleratedDelta.deltaX;
+    mPendingScrollAmountY += acceleratedDelta.deltaY;
+  } else {
+    mPendingScrollAmountX +=
+        aScrollAmountInDevPixels.width * acceleratedDelta.deltaX;
+    mPendingScrollAmountY +=
+        aScrollAmountInDevPixels.height * acceleratedDelta.deltaY;
+  }
+  result.x = RoundDown(mPendingScrollAmountX);
+  result.y = RoundDown(mPendingScrollAmountY);
+  mPendingScrollAmountX -= result.x;
+  mPendingScrollAmountY -= result.y;
+
+  return result;
+}
+
+/******************************************************************/
+/* mozilla::EventStateManager::WheelPrefs                         */
+/******************************************************************/
+
+// static
+EventStateManager::WheelPrefs* EventStateManager::WheelPrefs::GetInstance() {
+  if (!sInstance) {
+    sInstance = new WheelPrefs();
+  }
+  return sInstance;
+}
+
+// static
+void EventStateManager::WheelPrefs::Shutdown() {
+  delete sInstance;
+  sInstance = nullptr;
+}
+
+// static
+void EventStateManager::WheelPrefs::OnPrefChanged(const char* aPrefName,
+                                                  void* aClosure) {
+  // forget all prefs, it's not problem for performance.
+  sInstance->Reset();
+  DeltaAccumulator::GetInstance()->Reset();
+}
+
+EventStateManager::WheelPrefs::WheelPrefs() {
+  Reset();
+  Preferences::RegisterPrefixCallback(OnPrefChanged, "mousewheel.");
+}
+
+EventStateManager::WheelPrefs::~WheelPrefs() {
+  Preferences::UnregisterPrefixCallback(OnPrefChanged, "mousewheel.");
+}
+
+void EventStateManager::WheelPrefs::Reset() { memset(mInit, 0, sizeof(mInit)); }
+
+EventStateManager::WheelPrefs::Index EventStateManager::WheelPrefs::GetIndexFor(
+    const WidgetWheelEvent* aEvent) {
+  if (!aEvent) {
+    return INDEX_DEFAULT;
+  }
+
+  Modifiers modifiers =
+      (aEvent->mModifiers & (MODIFIER_ALT | MODIFIER_CONTROL | MODIFIER_META |
+                             MODIFIER_SHIFT | MODIFIER_OS));
+
+  switch (modifiers) {
+    case MODIFIER_ALT:
+      return INDEX_ALT;
+    case MODIFIER_CONTROL:
+      return INDEX_CONTROL;
+    case MODIFIER_META:
+      return INDEX_META;
+    case MODIFIER_SHIFT:
+      return INDEX_SHIFT;
+    case MODIFIER_OS:
+      return INDEX_OS;
+    default:
+      // If two or more modifier keys are pressed, we should use default
+      // settings.
+      return INDEX_DEFAULT;
+  }
+}
+
+void EventStateManager::WheelPrefs::GetBasePrefName(
+    EventStateManager::WheelPrefs::Index aIndex, nsACString& aBasePrefName) {
+  aBasePrefName.AssignLiteral("mousewheel.");
+  switch (aIndex) {
+    case INDEX_ALT:
+      aBasePrefName.AppendLiteral("with_alt.");
+      break;
+    case INDEX_CONTROL:
+      aBasePrefName.AppendLiteral("with_control.");
+      break;
+    case INDEX_META:
+      aBasePrefName.AppendLiteral("with_meta.");
+      break;
+    case INDEX_SHIFT:
+      aBasePrefName.AppendLiteral("with_shift.");
+      break;
+    case INDEX_OS:
+      aBasePrefName.AppendLiteral("with_win.");
+      break;
+    case INDEX_DEFAULT:
+    default:
+      aBasePrefName.AppendLiteral("default.");
+      break;
+  }
+}
+
+void EventStateManager::WheelPrefs::Init(
+    EventStateManager::WheelPrefs::Index aIndex) {
+  if (mInit[aIndex]) {
+    return;
+  }
+  mInit[aIndex] = true;
+
+  nsAutoCString basePrefName;
+  GetBasePrefName(aIndex, basePrefName);
+
+  nsAutoCString prefNameX(basePrefName);
+  prefNameX.AppendLiteral("delta_multiplier_x");
+  mMultiplierX[aIndex] =
+      static_cast<double>(Preferences::GetInt(prefNameX.get(), 100)) / 100;
+
+  nsAutoCString prefNameY(basePrefName);
+  prefNameY.AppendLiteral("delta_multiplier_y");
+  mMultiplierY[aIndex] =
+      static_cast<double>(Preferences::GetInt(prefNameY.get(), 100)) / 100;
+
+  nsAutoCString prefNameZ(basePrefName);
+  prefNameZ.AppendLiteral("delta_multiplier_z");
+  mMultiplierZ[aIndex] =
+      static_cast<double>(Preferences::GetInt(prefNameZ.get(), 100)) / 100;
+
+  nsAutoCString prefNameAction(basePrefName);
+  prefNameAction.AppendLiteral("action");
+  int32_t action = Preferences::GetInt(prefNameAction.get(), ACTION_SCROLL);
+  if (action < int32_t(ACTION_NONE) || action > int32_t(ACTION_LAST)) {
+    NS_WARNING("Unsupported action pref value, replaced with 'Scroll'.");
+    action = ACTION_SCROLL;
+  }
+  mActions[aIndex] = static_cast<Action>(action);
+
+  // Compute action values overridden by .override_x pref.
+  // At present, override is possible only for the x-direction
+  // because this pref is introduced mainly for tilt wheels.
+  // Note that ACTION_HORIZONTALIZED_SCROLL isn't a valid value for this pref
+  // because it affects only to deltaY.
+  prefNameAction.AppendLiteral(".override_x");
+  int32_t actionOverrideX = Preferences::GetInt(prefNameAction.get(), -1);
+  if (actionOverrideX < -1 || actionOverrideX > int32_t(ACTION_LAST) ||
+      actionOverrideX == ACTION_HORIZONTALIZED_SCROLL) {
+    NS_WARNING("Unsupported action override pref value, didn't override.");
+    actionOverrideX = -1;
+  }
+  mOverriddenActionsX[aIndex] = (actionOverrideX == -1)
+                                    ? static_cast<Action>(action)
+                                    : static_cast<Action>(actionOverrideX);
+}
+
+void EventStateManager::WheelPrefs::GetMultiplierForDeltaXAndY(
+    const WidgetWheelEvent* aEvent, Index aIndex, double* aMultiplierForDeltaX,
+    double* aMultiplierForDeltaY) {
+  *aMultiplierForDeltaX = mMultiplierX[aIndex];
+  *aMultiplierForDeltaY = mMultiplierY[aIndex];
+  // If the event has been horizontalized(I.e. treated as a horizontal wheel
+  // scroll for a vertical wheel scroll), then we should swap mMultiplierX and
+  // mMultiplierY. By doing this, multipliers will still apply to the delta
+  // values they origianlly corresponded to.
+  if (aEvent->mDeltaValuesHorizontalizedForDefaultHandler &&
+      ComputeActionFor(aEvent) == ACTION_HORIZONTALIZED_SCROLL) {
+    std::swap(*aMultiplierForDeltaX, *aMultiplierForDeltaY);
+  }
+}
+
+void EventStateManager::WheelPrefs::ApplyUserPrefsToDelta(
+    WidgetWheelEvent* aEvent) {
+  if (aEvent->mCustomizedByUserPrefs) {
+    return;
+  }
+
+  Index index = GetIndexFor(aEvent);
+  Init(index);
+
+  double multiplierForDeltaX = 1.0, multiplierForDeltaY = 1.0;
+  GetMultiplierForDeltaXAndY(aEvent, index, &multiplierForDeltaX,
+                             &multiplierForDeltaY);
+  aEvent->mDeltaX *= multiplierForDeltaX;
+  aEvent->mDeltaY *= multiplierForDeltaY;
+  aEvent->mDeltaZ *= mMultiplierZ[index];
+
+  // If the multiplier is 1.0 or -1.0, i.e., it doesn't change the absolute
+  // value, we should use lineOrPageDelta values which were set by widget.
+  // Otherwise, we need to compute them from accumulated delta values.
+  if (!NeedToComputeLineOrPageDelta(aEvent)) {
+    aEvent->mLineOrPageDeltaX *= static_cast<int32_t>(multiplierForDeltaX);
+    aEvent->mLineOrPageDeltaY *= static_cast<int32_t>(multiplierForDeltaY);
+  } else {
+    aEvent->mLineOrPageDeltaX = 0;
+    aEvent->mLineOrPageDeltaY = 0;
+  }
+
+  aEvent->mCustomizedByUserPrefs =
+      ((mMultiplierX[index] != 1.0) || (mMultiplierY[index] != 1.0) ||
+       (mMultiplierZ[index] != 1.0));
+}
+
+void EventStateManager::WheelPrefs::CancelApplyingUserPrefsFromOverflowDelta(
+    WidgetWheelEvent* aEvent) {
+  Index index = GetIndexFor(aEvent);
+  Init(index);
+
+  // XXX If the multiplier pref value is negative, the scroll direction was
+  //     changed and caused to scroll different direction.  In such case,
+  //     this method reverts the sign of overflowDelta.  Does it make widget
+  //     happy?  Although, widget can know the pref applied delta values by
+  //     referrencing the deltaX and deltaY of the event.
+
+  double multiplierForDeltaX = 1.0, multiplierForDeltaY = 1.0;
+  GetMultiplierForDeltaXAndY(aEvent, index, &multiplierForDeltaX,
+                             &multiplierForDeltaY);
+  if (multiplierForDeltaX) {
+    aEvent->mOverflowDeltaX /= multiplierForDeltaX;
+  }
+  if (multiplierForDeltaY) {
+    aEvent->mOverflowDeltaY /= multiplierForDeltaY;
+  }
+}
+
+EventStateManager::WheelPrefs::Action
+EventStateManager::WheelPrefs::ComputeActionFor(
+    const WidgetWheelEvent* aEvent) {
+  Index index = GetIndexFor(aEvent);
+  Init(index);
+
+  bool deltaXPreferred = (Abs(aEvent->mDeltaX) > Abs(aEvent->mDeltaY) &&
+                          Abs(aEvent->mDeltaX) > Abs(aEvent->mDeltaZ));
+  Action* actions = deltaXPreferred ? mOverriddenActionsX : mActions;
+  if (actions[index] == ACTION_NONE || actions[index] == ACTION_SCROLL ||
+      actions[index] == ACTION_HORIZONTALIZED_SCROLL) {
+    return actions[index];
+  }
+
+  // Momentum events shouldn't run special actions.
+  if (aEvent->mIsMomentum) {
+    // Use the default action.  Note that user might kill the wheel scrolling.
+    Init(INDEX_DEFAULT);
+    if (actions[INDEX_DEFAULT] == ACTION_SCROLL ||
+        actions[INDEX_DEFAULT] == ACTION_HORIZONTALIZED_SCROLL) {
+      return actions[INDEX_DEFAULT];
+    }
+    return ACTION_NONE;
+  }
+
+  return actions[index];
+}
+
+bool EventStateManager::WheelPrefs::NeedToComputeLineOrPageDelta(
+    const WidgetWheelEvent* aEvent) {
+  Index index = GetIndexFor(aEvent);
+  Init(index);
+
+  return (mMultiplierX[index] != 1.0 && mMultiplierX[index] != -1.0) ||
+         (mMultiplierY[index] != 1.0 && mMultiplierY[index] != -1.0);
+}
+
+void EventStateManager::WheelPrefs::GetUserPrefsForEvent(
+    const WidgetWheelEvent* aEvent, double* aOutMultiplierX,
+    double* aOutMultiplierY) {
+  Index index = GetIndexFor(aEvent);
+  Init(index);
+
+  double multiplierForDeltaX = 1.0, multiplierForDeltaY = 1.0;
+  GetMultiplierForDeltaXAndY(aEvent, index, &multiplierForDeltaX,
+                             &multiplierForDeltaY);
+  *aOutMultiplierX = multiplierForDeltaX;
+  *aOutMultiplierY = multiplierForDeltaY;
+}
+
+// static
+Maybe<layers::APZWheelAction> EventStateManager::APZWheelActionFor(
+    const WidgetWheelEvent* aEvent) {
+  if (aEvent->mMessage != eWheel) {
+    return Nothing();
+  }
+  WheelPrefs::Action action =
+      WheelPrefs::GetInstance()->ComputeActionFor(aEvent);
+  switch (action) {
+    case WheelPrefs::ACTION_SCROLL:
+    case WheelPrefs::ACTION_HORIZONTALIZED_SCROLL:
+      return Some(layers::APZWheelAction::Scroll);
+    case WheelPrefs::ACTION_PINCH_ZOOM:
+      return Some(layers::APZWheelAction::PinchZoom);
+    default:
+      return Nothing();
+  }
+}
+
+// static
+WheelDeltaAdjustmentStrategy EventStateManager::GetWheelDeltaAdjustmentStrategy(
+    const WidgetWheelEvent& aEvent) {
+  if (aEvent.mMessage != eWheel) {
+    return WheelDeltaAdjustmentStrategy::eNone;
+  }
+  switch (WheelPrefs::GetInstance()->ComputeActionFor(&aEvent)) {
+    case WheelPrefs::ACTION_SCROLL:
+      if (StaticPrefs::mousewheel_autodir_enabled() && 0 == aEvent.mDeltaZ) {
+        if (StaticPrefs::mousewheel_autodir_honourroot()) {
+          return WheelDeltaAdjustmentStrategy::eAutoDirWithRootHonour;
+        }
+        return WheelDeltaAdjustmentStrategy::eAutoDir;
+      }
+      return WheelDeltaAdjustmentStrategy::eNone;
+    case WheelPrefs::ACTION_HORIZONTALIZED_SCROLL:
+      return WheelDeltaAdjustmentStrategy::eHorizontalize;
+    default:
+      break;
+  }
+  return WheelDeltaAdjustmentStrategy::eNone;
+}
+
+void EventStateManager::GetUserPrefsForWheelEvent(
+    const WidgetWheelEvent* aEvent, double* aOutMultiplierX,
+    double* aOutMultiplierY) {
+  WheelPrefs::GetInstance()->GetUserPrefsForEvent(aEvent, aOutMultiplierX,
+                                                  aOutMultiplierY);
+}
+
+bool EventStateManager::WheelPrefs::IsOverOnePageScrollAllowedX(
+    const WidgetWheelEvent* aEvent) {
+  Index index = GetIndexFor(aEvent);
+  Init(index);
+  return Abs(mMultiplierX[index]) >=
+         MIN_MULTIPLIER_VALUE_ALLOWING_OVER_ONE_PAGE_SCROLL;
+}
+
+bool EventStateManager::WheelPrefs::IsOverOnePageScrollAllowedY(
+    const WidgetWheelEvent* aEvent) {
+  Index index = GetIndexFor(aEvent);
+  Init(index);
+  return Abs(mMultiplierY[index]) >=
+         MIN_MULTIPLIER_VALUE_ALLOWING_OVER_ONE_PAGE_SCROLL;
+}
+
+}  // namespace mozilla