import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

widget/MouseEvents.h

@@ -0,0 +1,724 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#ifndef mozilla_MouseEvents_h__
+#define mozilla_MouseEvents_h__
+
+#include <stdint.h>
+
+#include "mozilla/BasicEvents.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/dom/DataTransfer.h"
+#include "nsCOMPtr.h"
+#include "nsIDOMMouseEvent.h"
+#include "nsIDOMWheelEvent.h"
+
+/******************************************************************************
+ * nsDragDropEventStatus
+ ******************************************************************************/
+
+enum nsDragDropEventStatus
+{  
+  // The event is a enter
+  nsDragDropEventStatus_eDragEntered,
+  // The event is exit
+  nsDragDropEventStatus_eDragExited,
+  // The event is drop
+  nsDragDropEventStatus_eDrop
+};
+
+namespace mozilla {
+
+namespace dom {
+  class PBrowserParent;
+  class PBrowserChild;
+} // namespace dom
+
+/******************************************************************************
+ * mozilla::WidgetPointerHelper
+ ******************************************************************************/
+
+class WidgetPointerHelper
+{
+public:
+  bool convertToPointer;
+  uint32_t pointerId;
+  uint32_t tiltX;
+  uint32_t tiltY;
+  bool retargetedByPointerCapture;
+
+  WidgetPointerHelper() : convertToPointer(true), pointerId(0), tiltX(0), tiltY(0),
+                          retargetedByPointerCapture(false) {}
+
+  void AssignPointerHelperData(const WidgetPointerHelper& aEvent)
+  {
+    convertToPointer = aEvent.convertToPointer;
+    pointerId = aEvent.pointerId;
+    tiltX = aEvent.tiltX;
+    tiltY = aEvent.tiltY;
+    retargetedByPointerCapture = aEvent.retargetedByPointerCapture;
+  }
+};
+
+/******************************************************************************
+ * mozilla::WidgetMouseEventBase
+ ******************************************************************************/
+
+class WidgetMouseEventBase : public WidgetInputEvent
+{
+private:
+  friend class dom::PBrowserParent;
+  friend class dom::PBrowserChild;
+
+protected:
+  WidgetMouseEventBase()
+    : button(0)
+    , buttons(0)
+    , pressure(0)
+    , hitCluster(false)
+    , inputSource(nsIDOMMouseEvent::MOZ_SOURCE_MOUSE)
+  {
+  }
+
+  WidgetMouseEventBase(bool aIsTrusted, EventMessage aMessage,
+                       nsIWidget* aWidget, EventClassID aEventClassID)
+    : WidgetInputEvent(aIsTrusted, aMessage, aWidget, aEventClassID)
+    , button(0)
+    , buttons(0)
+    , pressure(0)
+    , hitCluster(false)
+    , inputSource(nsIDOMMouseEvent::MOZ_SOURCE_MOUSE)
+ {
+ }
+
+public:
+  virtual WidgetMouseEventBase* AsMouseEventBase() override { return this; }
+
+  virtual WidgetEvent* Duplicate() const override
+  {
+    MOZ_CRASH("WidgetMouseEventBase must not be most-subclass");
+  }
+
+  /// The possible related target
+  nsCOMPtr<nsISupports> relatedTarget;
+
+  enum buttonType
+  {
+    eLeftButton   = 0,
+    eMiddleButton = 1,
+    eRightButton  = 2
+  };
+  // Pressed button ID of mousedown or mouseup event.
+  // This is set only when pressing a button causes the event.
+  int16_t button;
+
+  enum buttonsFlag {
+    eNoButtonFlag     = 0x00,
+    eLeftButtonFlag   = 0x01,
+    eRightButtonFlag  = 0x02,
+    eMiddleButtonFlag = 0x04,
+    // typicall, "back" button being left side of 5-button
+    // mice, see "buttons" attribute document of DOM3 Events.
+    e4thButtonFlag    = 0x08,
+    // typicall, "forward" button being right side of 5-button
+    // mice, see "buttons" attribute document of DOM3 Events.
+    e5thButtonFlag    = 0x10
+  };
+
+  // Flags of all pressed buttons at the event fired.
+  // This is set at any mouse event, don't be confused with |button|.
+  int16_t buttons;
+
+  // Finger or touch pressure of event. It ranges between 0.0 and 1.0.
+  float pressure;
+  // Touch near a cluster of links (true)
+  bool hitCluster;
+
+  // Possible values at nsIDOMMouseEvent
+  uint16_t inputSource;
+
+  // ID of the canvas HitRegion
+  nsString region;
+
+  bool IsLeftButtonPressed() const { return !!(buttons & eLeftButtonFlag); }
+  bool IsRightButtonPressed() const { return !!(buttons & eRightButtonFlag); }
+  bool IsMiddleButtonPressed() const { return !!(buttons & eMiddleButtonFlag); }
+  bool Is4thButtonPressed() const { return !!(buttons & e4thButtonFlag); }
+  bool Is5thButtonPressed() const { return !!(buttons & e5thButtonFlag); }
+
+  void AssignMouseEventBaseData(const WidgetMouseEventBase& aEvent,
+                                bool aCopyTargets)
+  {
+    AssignInputEventData(aEvent, aCopyTargets);
+
+    relatedTarget = aCopyTargets ? aEvent.relatedTarget : nullptr;
+    button = aEvent.button;
+    buttons = aEvent.buttons;
+    pressure = aEvent.pressure;
+    hitCluster = aEvent.hitCluster;
+    inputSource = aEvent.inputSource;
+  }
+
+  /**
+   * Returns true if left click event.
+   */
+  bool IsLeftClickEvent() const
+  {
+    return mMessage == eMouseClick && button == eLeftButton;
+  }
+};
+
+/******************************************************************************
+ * mozilla::WidgetMouseEvent
+ ******************************************************************************/
+
+class WidgetMouseEvent : public WidgetMouseEventBase
+                       , public WidgetPointerHelper
+{
+private:
+  friend class dom::PBrowserParent;
+  friend class dom::PBrowserChild;
+
+public:
+  typedef bool ReasonType;
+  enum Reason : ReasonType
+  {
+    eReal,
+    eSynthesized
+  };
+
+  typedef bool ContextMenuTriggerType;
+  enum ContextMenuTrigger : ContextMenuTriggerType
+  {
+    eNormal,
+    eContextMenuKey
+  };
+
+  typedef bool ExitFromType;
+  enum ExitFrom : ExitFromType
+  {
+    eChild,
+    eTopLevel
+  };
+
+protected:
+  WidgetMouseEvent()
+    : mReason(eReal)
+    , mContextMenuTrigger(eNormal)
+    , mExitFrom(eChild)
+    , mIgnoreRootScrollFrame(false)
+    , mClickCount(0)
+  {
+  }
+
+  WidgetMouseEvent(bool aIsTrusted,
+                   EventMessage aMessage,
+                   nsIWidget* aWidget,
+                   EventClassID aEventClassID,
+                   Reason aReason)
+    : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, aEventClassID)
+    , mReason(aReason)
+    , mContextMenuTrigger(eNormal)
+    , mExitFrom(eChild)
+    , mIgnoreRootScrollFrame(false)
+    , mClickCount(0)
+  {
+  }
+
+public:
+  virtual WidgetMouseEvent* AsMouseEvent() override { return this; }
+
+  WidgetMouseEvent(bool aIsTrusted,
+                   EventMessage aMessage,
+                   nsIWidget* aWidget,
+                   Reason aReason,
+                   ContextMenuTrigger aContextMenuTrigger = eNormal)
+    : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, eMouseEventClass)
+    , mReason(aReason)
+    , mContextMenuTrigger(aContextMenuTrigger)
+    , mExitFrom(eChild)
+    , mIgnoreRootScrollFrame(false)
+    , mClickCount(0)
+  {
+    if (aMessage == eContextMenu) {
+      button = (mContextMenuTrigger == eNormal) ? eRightButton : eLeftButton;
+    }
+  }
+
+#ifdef DEBUG
+  virtual ~WidgetMouseEvent()
+  {
+    NS_WARNING_ASSERTION(
+      mMessage != eContextMenu ||
+      button == ((mContextMenuTrigger == eNormal) ? eRightButton : eLeftButton),
+      "Wrong button set to eContextMenu event?");
+  }
+#endif
+
+  virtual WidgetEvent* Duplicate() const override
+  {
+    MOZ_ASSERT(mClass == eMouseEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetMouseEvent* result =
+      new WidgetMouseEvent(false, mMessage, nullptr,
+                           mReason, mContextMenuTrigger);
+    result->AssignMouseEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  // mReason indicates the reason why the event is fired:
+  // - Representing mouse operation.
+  // - Synthesized for emulating mousemove event when the content under the
+  //   mouse cursor is scrolled.
+  Reason mReason;
+
+  // mContextMenuTrigger is valid only when mMessage is eContextMenu.
+  // This indicates if the context menu event is caused by context menu key or
+  // other reasons (typically, a click of right mouse button).
+  ContextMenuTrigger mContextMenuTrigger;
+
+  // mExitFrom is valid only when mMessage is eMouseExitFromWidget.
+  // This indicates if the mouse cursor exits from a top level widget or
+  // a child widget.
+  ExitFrom mExitFrom;
+
+  // Whether the event should ignore scroll frame bounds during dispatch.
+  bool mIgnoreRootScrollFrame;
+
+  // mClickCount may be non-zero value when mMessage is eMouseDown, eMouseUp,
+  // eMouseClick or eMouseDoubleClick. The number is count of mouse clicks.
+  // Otherwise, this must be 0.
+  uint32_t mClickCount;
+
+  void AssignMouseEventData(const WidgetMouseEvent& aEvent, bool aCopyTargets)
+  {
+    AssignMouseEventBaseData(aEvent, aCopyTargets);
+    AssignPointerHelperData(aEvent);
+
+    mIgnoreRootScrollFrame = aEvent.mIgnoreRootScrollFrame;
+    mClickCount = aEvent.mClickCount;
+  }
+
+  /**
+   * Returns true if the event is a context menu event caused by key.
+   */
+  bool IsContextMenuKeyEvent() const
+  {
+    return mMessage == eContextMenu && mContextMenuTrigger == eContextMenuKey;
+  }
+
+  /**
+   * Returns true if the event is a real mouse event.  Otherwise, i.e., it's
+   * a synthesized event by scroll or something, returns false.
+   */
+  bool IsReal() const
+  {
+    return mReason == eReal;
+  }
+};
+
+/******************************************************************************
+ * mozilla::WidgetDragEvent
+ ******************************************************************************/
+
+class WidgetDragEvent : public WidgetMouseEvent
+{
+private:
+  friend class mozilla::dom::PBrowserParent;
+  friend class mozilla::dom::PBrowserChild;
+protected:
+  WidgetDragEvent()
+    : mUserCancelled(false)
+    , mDefaultPreventedOnContent(false)
+  {
+  }
+public:
+  virtual WidgetDragEvent* AsDragEvent() override { return this; }
+
+  WidgetDragEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget)
+    : WidgetMouseEvent(aIsTrusted, aMessage, aWidget, eDragEventClass, eReal)
+    , mUserCancelled(false)
+    , mDefaultPreventedOnContent(false)
+  {
+  }
+
+  virtual WidgetEvent* Duplicate() const override
+  {
+    MOZ_ASSERT(mClass == eDragEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetDragEvent* result = new WidgetDragEvent(false, mMessage, nullptr);
+    result->AssignDragEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  // The dragging data.
+  nsCOMPtr<dom::DataTransfer> mDataTransfer;
+
+  // If this is true, user has cancelled the drag operation.
+  bool mUserCancelled;
+  // If this is true, the drag event's preventDefault() is called on content.
+  bool mDefaultPreventedOnContent;
+
+  // XXX Not tested by test_assign_event_data.html
+  void AssignDragEventData(const WidgetDragEvent& aEvent, bool aCopyTargets)
+  {
+    AssignMouseEventData(aEvent, aCopyTargets);
+
+    mDataTransfer = aEvent.mDataTransfer;
+    // XXX mUserCancelled isn't copied, is this intentionally?
+    mUserCancelled = false;
+    mDefaultPreventedOnContent = aEvent.mDefaultPreventedOnContent;
+  }
+};
+
+/******************************************************************************
+ * mozilla::WidgetMouseScrollEvent
+ *
+ * This is used for legacy DOM mouse scroll events, i.e.,
+ * DOMMouseScroll and MozMousePixelScroll event.  These events are NOT hanbled
+ * by ESM even if widget dispatches them.  Use new WidgetWheelEvent instead.
+ ******************************************************************************/
+
+class WidgetMouseScrollEvent : public WidgetMouseEventBase
+{
+private:
+  WidgetMouseScrollEvent()
+    : mDelta(0)
+    , mIsHorizontal(false)
+  {
+  }
+
+public:
+  virtual WidgetMouseScrollEvent* AsMouseScrollEvent() override
+  {
+    return this;
+  }
+
+  WidgetMouseScrollEvent(bool aIsTrusted, EventMessage aMessage,
+                         nsIWidget* aWidget)
+    : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget,
+                           eMouseScrollEventClass)
+    , mDelta(0)
+    , mIsHorizontal(false)
+  {
+  }
+
+  virtual WidgetEvent* Duplicate() const override
+  {
+    MOZ_ASSERT(mClass == eMouseScrollEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetMouseScrollEvent* result =
+      new WidgetMouseScrollEvent(false, mMessage, nullptr);
+    result->AssignMouseScrollEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  // The delta value of mouse scroll event.
+  // If the event message is eLegacyMouseLineOrPageScroll, the value indicates
+  // scroll amount in lines.  However, if the value is
+  // nsIDOMUIEvent::SCROLL_PAGE_UP or nsIDOMUIEvent::SCROLL_PAGE_DOWN, the
+  // value inducates one page scroll.  If the event message is
+  // eLegacyMousePixelScroll, the value indicates scroll amount in pixels.
+  int32_t mDelta;
+
+  // If this is true, it may cause to scroll horizontally.
+  // Otherwise, vertically.
+  bool mIsHorizontal;
+
+  void AssignMouseScrollEventData(const WidgetMouseScrollEvent& aEvent,
+                                  bool aCopyTargets)
+  {
+    AssignMouseEventBaseData(aEvent, aCopyTargets);
+
+    mDelta = aEvent.mDelta;
+    mIsHorizontal = aEvent.mIsHorizontal;
+  }
+};
+
+/******************************************************************************
+ * mozilla::WidgetWheelEvent
+ ******************************************************************************/
+
+class WidgetWheelEvent : public WidgetMouseEventBase
+{
+private:
+  friend class mozilla::dom::PBrowserParent;
+  friend class mozilla::dom::PBrowserChild;
+
+  WidgetWheelEvent()
+    : mDeltaX(0.0)
+    , mDeltaY(0.0)
+    , mDeltaZ(0.0)
+    , mOverflowDeltaX(0.0)
+    , mOverflowDeltaY(0.0)
+    , mDeltaMode(nsIDOMWheelEvent::DOM_DELTA_PIXEL)
+    , mLineOrPageDeltaX(0)
+    , mLineOrPageDeltaY(0)
+    , mScrollType(SCROLL_DEFAULT)
+    , mCustomizedByUserPrefs(false)
+    , mIsMomentum(false)
+    , mIsNoLineOrPageDelta(false)
+    , mViewPortIsOverscrolled(false)
+    , mCanTriggerSwipe(false)
+    , mAllowToOverrideSystemScrollSpeed(false)
+  {
+  }
+
+public:
+  virtual WidgetWheelEvent* AsWheelEvent() override { return this; }
+
+  WidgetWheelEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget)
+    : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, eWheelEventClass)
+    , mDeltaX(0.0)
+    , mDeltaY(0.0)
+    , mDeltaZ(0.0)
+    , mOverflowDeltaX(0.0)
+    , mOverflowDeltaY(0.0)
+    , mDeltaMode(nsIDOMWheelEvent::DOM_DELTA_PIXEL)
+    , mLineOrPageDeltaX(0)
+    , mLineOrPageDeltaY(0)
+    , mScrollType(SCROLL_DEFAULT)
+    , mCustomizedByUserPrefs(false)
+    , mMayHaveMomentum(false)
+    , mIsMomentum(false)
+    , mIsNoLineOrPageDelta(false)
+    , mViewPortIsOverscrolled(false)
+    , mCanTriggerSwipe(false)
+    , mAllowToOverrideSystemScrollSpeed(true)
+  {
+  }
+
+  virtual WidgetEvent* Duplicate() const override
+  {
+    MOZ_ASSERT(mClass == eWheelEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetWheelEvent* result = new WidgetWheelEvent(false, mMessage, nullptr);
+    result->AssignWheelEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  // On OS X, scroll gestures that start at the edge of the scrollable range
+  // can result in a swipe gesture. For the first wheel event of such a
+  // gesture, call TriggersSwipe() after the event has been processed
+  // in order to find out whether a swipe should be started.
+  bool TriggersSwipe() const
+  {
+    return mCanTriggerSwipe && mViewPortIsOverscrolled &&
+           this->mOverflowDeltaX != 0.0;
+  }
+
+  // NOTE: mDeltaX, mDeltaY and mDeltaZ may be customized by
+  //       mousewheel.*.delta_multiplier_* prefs which are applied by
+  //       EventStateManager.  So, after widget dispatches this event,
+  //       these delta values may have different values than before.
+  double mDeltaX;
+  double mDeltaY;
+  double mDeltaZ;
+
+  // overflowed delta values for scroll, these values are set by
+  // nsEventStateManger.  If the default action of the wheel event isn't scroll,
+  // these values always zero.  Otherwise, remaning delta values which are
+  // not used by scroll are set.
+  // NOTE: mDeltaX, mDeltaY and mDeltaZ may be modified by EventStateManager.
+  //       However, mOverflowDeltaX and mOverflowDeltaY indicate unused original
+  //       delta values which are not applied the delta_multiplier prefs.
+  //       So, if widget wanted to know the actual direction to be scrolled,
+  //       it would need to check the mDeltaX and mDeltaY.
+  double mOverflowDeltaX;
+  double mOverflowDeltaY;
+
+  // Should be one of nsIDOMWheelEvent::DOM_DELTA_*
+  uint32_t mDeltaMode;
+
+  // If widget sets mLineOrPageDelta, EventStateManager will dispatch
+  // eLegacyMouseLineOrPageScroll event for compatibility.  Note that the delta
+  // value means pages if the mDeltaMode is DOM_DELTA_PAGE, otherwise, lines.
+  int32_t mLineOrPageDeltaX;
+  int32_t mLineOrPageDeltaY;
+
+  // When the default action for an wheel event is moving history or zooming,
+  // need to chose a delta value for doing it.
+  int32_t GetPreferredIntDelta()
+  {
+    if (!mLineOrPageDeltaX && !mLineOrPageDeltaY) {
+      return 0;
+    }
+    if (mLineOrPageDeltaY && !mLineOrPageDeltaX) {
+      return mLineOrPageDeltaY;
+    }
+    if (mLineOrPageDeltaX && !mLineOrPageDeltaY) {
+      return mLineOrPageDeltaX;
+    }
+    if ((mLineOrPageDeltaX < 0 && mLineOrPageDeltaY > 0) ||
+        (mLineOrPageDeltaX > 0 && mLineOrPageDeltaY < 0)) {
+      return 0; // We cannot guess the answer in this case.
+    }
+    return (Abs(mLineOrPageDeltaX) > Abs(mLineOrPageDeltaY)) ?
+             mLineOrPageDeltaX : mLineOrPageDeltaY;
+  }
+
+  // Scroll type
+  // The default value is SCROLL_DEFAULT, which means EventStateManager will
+  // select preferred scroll type automatically.
+  enum ScrollType : uint8_t
+  {
+    SCROLL_DEFAULT,
+    SCROLL_SYNCHRONOUSLY,
+    SCROLL_ASYNCHRONOUSELY,
+    SCROLL_SMOOTHLY
+  };
+  ScrollType mScrollType;
+
+  // If the delta values are computed from prefs, this value is true.
+  // Otherwise, i.e., they are computed from native events, false.
+  bool mCustomizedByUserPrefs;
+
+  // true if the momentum events directly tied to this event may follow it.
+  bool mMayHaveMomentum;
+  // true if the event is caused by momentum.
+  bool mIsMomentum;
+
+  // If device event handlers don't know when they should set mLineOrPageDeltaX
+  // and mLineOrPageDeltaY, this is true.  Otherwise, false.
+  // If mIsNoLineOrPageDelta is true, ESM will generate
+  // eLegacyMouseLineOrPageScroll events when accumulated delta values reach
+  // a line height.
+  bool mIsNoLineOrPageDelta;
+
+  // Whether or not the parent of the currently overscrolled frame is the
+  // ViewPort. This is false in situations when an element on the page is being
+  // overscrolled (such as a text field), but true when the 'page' is being
+  // overscrolled.
+  bool mViewPortIsOverscrolled;
+
+  // The wheel event can trigger a swipe to start if it's overscrolling the
+  // viewport.
+  bool mCanTriggerSwipe;
+
+  // If mAllowToOverrideSystemScrollSpeed is true, the scroll speed may be
+  // overridden.  Otherwise, the scroll speed won't be overridden even if
+  // it's enabled by the pref.
+  bool mAllowToOverrideSystemScrollSpeed;
+
+  void AssignWheelEventData(const WidgetWheelEvent& aEvent, bool aCopyTargets)
+  {
+    AssignMouseEventBaseData(aEvent, aCopyTargets);
+
+    mDeltaX = aEvent.mDeltaX;
+    mDeltaY = aEvent.mDeltaY;
+    mDeltaZ = aEvent.mDeltaZ;
+    mDeltaMode = aEvent.mDeltaMode;
+    mCustomizedByUserPrefs = aEvent.mCustomizedByUserPrefs;
+    mMayHaveMomentum = aEvent.mMayHaveMomentum;
+    mIsMomentum = aEvent.mIsMomentum;
+    mIsNoLineOrPageDelta = aEvent.mIsNoLineOrPageDelta;
+    mLineOrPageDeltaX = aEvent.mLineOrPageDeltaX;
+    mLineOrPageDeltaY = aEvent.mLineOrPageDeltaY;
+    mScrollType = aEvent.mScrollType;
+    mOverflowDeltaX = aEvent.mOverflowDeltaX;
+    mOverflowDeltaY = aEvent.mOverflowDeltaY;
+    mViewPortIsOverscrolled = aEvent.mViewPortIsOverscrolled;
+    mCanTriggerSwipe = aEvent.mCanTriggerSwipe;
+    mAllowToOverrideSystemScrollSpeed =
+      aEvent.mAllowToOverrideSystemScrollSpeed;
+  }
+
+  // System scroll speed settings may be too slow at using Gecko.  In such
+  // case, we should override the scroll speed computed with system settings.
+  // Following methods return preferred delta values which are multiplied by
+  // factors specified by prefs.  If system scroll speed shouldn't be
+  // overridden (e.g., this feature is disabled by pref), they return raw
+  // delta values.
+  double OverriddenDeltaX() const;
+  double OverriddenDeltaY() const;
+
+  // Compute the overridden delta value.  This may be useful for suppressing
+  // too fast scroll by system scroll speed overriding when widget sets
+  // mAllowToOverrideSystemScrollSpeed.
+  static double ComputeOverriddenDelta(double aDelta, bool aIsForVertical);
+
+private:
+  static bool sInitialized;
+  static bool sIsSystemScrollSpeedOverrideEnabled;
+  static int32_t sOverrideFactorX;
+  static int32_t sOverrideFactorY;
+  static void Initialize();
+};
+
+/******************************************************************************
+ * mozilla::WidgetPointerEvent
+ ******************************************************************************/
+
+class WidgetPointerEvent : public WidgetMouseEvent
+{
+  friend class mozilla::dom::PBrowserParent;
+  friend class mozilla::dom::PBrowserChild;
+
+  WidgetPointerEvent()
+    : mWidth(1)
+    , mHeight(1)
+    , mIsPrimary(true)
+  {
+  }
+
+public:
+  virtual WidgetPointerEvent* AsPointerEvent() override { return this; }
+
+  WidgetPointerEvent(bool aIsTrusted, EventMessage aMsg, nsIWidget* w)
+    : WidgetMouseEvent(aIsTrusted, aMsg, w, ePointerEventClass, eReal)
+    , mWidth(1)
+    , mHeight(1)
+    , mIsPrimary(true)
+  {
+  }
+
+  explicit WidgetPointerEvent(const WidgetMouseEvent& aEvent)
+    : WidgetMouseEvent(aEvent)
+    , mWidth(1)
+    , mHeight(1)
+    , mIsPrimary(true)
+  {
+    mClass = ePointerEventClass;
+  }
+
+  virtual WidgetEvent* Duplicate() const override
+  {
+    MOZ_ASSERT(mClass == ePointerEventClass,
+               "Duplicate() must be overridden by sub class");
+    // Not copying widget, it is a weak reference.
+    WidgetPointerEvent* result =
+      new WidgetPointerEvent(false, mMessage, nullptr);
+    result->AssignPointerEventData(*this, true);
+    result->mFlags = mFlags;
+    return result;
+  }
+
+  uint32_t mWidth;
+  uint32_t mHeight;
+  bool mIsPrimary;
+
+  // XXX Not tested by test_assign_event_data.html
+  void AssignPointerEventData(const WidgetPointerEvent& aEvent,
+                              bool aCopyTargets)
+  {
+    AssignMouseEventData(aEvent, aCopyTargets);
+
+    mWidth = aEvent.mWidth;
+    mHeight = aEvent.mHeight;
+    mIsPrimary = aEvent.mIsPrimary;
+  }
+};
+
+} // namespace mozilla
+
+#endif // mozilla_MouseEvents_h__