--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -7788,17 +7788,17 @@ nsContentUtils::SendMouseEvent(nsCOMPtr<
   event.mTime = PR_IntervalNow();
   event.mFlags.mIsSynthesizedForTests = aIsSynthesized;
 
   nsPresContext* presContext = aPresShell->GetPresContext();
   if (!presContext)
     return NS_ERROR_FAILURE;
 
   event.mRefPoint = ToWidgetPoint(CSSPoint(aX, aY), offset, presContext);
-  event.ignoreRootScrollFrame = aIgnoreRootScrollFrame;
+  event.mIgnoreRootScrollFrame = aIgnoreRootScrollFrame;
 
   nsEventStatus status = nsEventStatus_eIgnore;
   if (aToWindow) {
     nsCOMPtr<nsIPresShell> presShell;
     nsView* view = GetViewToDispatchEvent(presContext, getter_AddRefs(presShell));
     if (!presShell || !view) {
       return NS_ERROR_FAILURE;
     }

--- a/dom/base/nsDOMWindowUtils.cpp
+++ b/dom/base/nsDOMWindowUtils.cpp
@@ -689,17 +689,17 @@ nsDOMWindowUtils::SendPointerEventCommon
 
   nsPresContext* presContext = GetPresContext();
   if (!presContext) {
     return NS_ERROR_FAILURE;
   }
 
   event.mRefPoint =
     nsContentUtils::ToWidgetPoint(CSSPoint(aX, aY), offset, presContext);
-  event.ignoreRootScrollFrame = aIgnoreRootScrollFrame;
+  event.mIgnoreRootScrollFrame = aIgnoreRootScrollFrame;
 
   nsEventStatus status;
   if (aToWindow) {
     nsCOMPtr<nsIPresShell> presShell;
     nsView* view = nsContentUtils::GetViewToDispatchEvent(presContext, getter_AddRefs(presShell));
     if (!presShell || !view) {
       return NS_ERROR_FAILURE;
     }

--- a/gfx/layers/apz/util/APZCCallbackHelper.cpp
+++ b/gfx/layers/apz/util/APZCCallbackHelper.cpp
@@ -482,17 +482,17 @@ APZCCallbackHelper::DispatchSynthesizedM
              aMsg == eMouseUp || aMsg == eMouseLongTap);
 
   WidgetMouseEvent event(true, aMsg, aWidget,
                          WidgetMouseEvent::eReal, WidgetMouseEvent::eNormal);
   event.mRefPoint = LayoutDeviceIntPoint(aRefPoint.x, aRefPoint.y);
   event.mTime = aTime;
   event.button = WidgetMouseEvent::eLeftButton;
   event.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_TOUCH;
-  event.ignoreRootScrollFrame = true;
+  event.mIgnoreRootScrollFrame = true;
   if (aMsg != eMouseMove) {
     event.clickCount = 1;
   }
   event.mModifiers = aModifiers;
 
   return DispatchWidgetEvent(event);
 }
 

--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -7663,17 +7663,17 @@ PresShell::HandleEvent(nsIFrame* aFrame,
               touch->SetTarget(oldTouch->mTarget);
             }
           }
         }
       } else {
         eventPoint = nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, frame);
       }
       if (mouseEvent && mouseEvent->mClass == eMouseEventClass &&
-          mouseEvent->ignoreRootScrollFrame) {
+          mouseEvent->mIgnoreRootScrollFrame) {
         flags |= INPUT_IGNORE_ROOT_SCROLL_FRAME;
       }
       nsIFrame* target =
         FindFrameTargetedByInputEvent(aEvent, frame, eventPoint, flags);
       if (target) {
         frame = target;
       }
     }

--- a/widget/InputData.cpp
+++ b/widget/InputData.cpp
@@ -158,17 +158,17 @@ MouseInput::ToWidgetMouseEvent(nsIWidget
   event.mModifiers = modifiers;
   event.mTime = mTime;
   event.mTimeStamp = mTimeStamp;
   event.mRefPoint =
     RoundedToInt(ViewAs<LayoutDevicePixel>(mOrigin,
       PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent));
   event.clickCount = clickCount;
   event.inputSource = mInputSource;
-  event.ignoreRootScrollFrame = true;
+  event.mIgnoreRootScrollFrame = true;
 
   return event;
 }
 
 MultiTouchInput::MultiTouchInput(const WidgetTouchEvent& aTouchEvent)
   : InputData(MULTITOUCH_INPUT, aTouchEvent.mTime, aTouchEvent.mTimeStamp,
               aTouchEvent.mModifiers)
   , mHandledByAPZ(aTouchEvent.mFlags.mHandledByAPZ)

--- a/widget/MouseEvents.h
+++ b/widget/MouseEvents.h
@@ -202,45 +202,45 @@ public:
     eTopLevel
   };
 
 protected:
   WidgetMouseEvent()
     : mReason(eReal)
     , mContextMenuTrigger(eNormal)
     , mExitFrom(eChild)
-    , ignoreRootScrollFrame(false)
+    , mIgnoreRootScrollFrame(false)
     , clickCount(0)
   {
   }
 
   WidgetMouseEvent(bool aIsTrusted, EventMessage aMessage, nsIWidget* aWidget,
                    EventClassID aEventClassID, Reason aReason)
     : WidgetMouseEventBase(aIsTrusted, aMessage, aWidget, aEventClassID)
     , mReason(aReason)
     , mContextMenuTrigger(eNormal)
     , mExitFrom(eChild)
-    , ignoreRootScrollFrame(false)
+    , mIgnoreRootScrollFrame(false)
     , clickCount(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)
-    , ignoreRootScrollFrame(false)
+    , mIgnoreRootScrollFrame(false)
     , clickCount(0)
   {
     if (aMessage == eContextMenu) {
       button = (mContextMenuTrigger == eNormal) ? eRightButton : eLeftButton;
     }
   }
 
 #ifdef DEBUG
@@ -269,27 +269,27 @@ public:
 
   Reason mReason;
 
   ContextMenuTrigger mContextMenuTrigger;
 
   ExitFrom mExitFrom;
 
   // Whether the event should ignore scroll frame bounds during dispatch.
-  bool ignoreRootScrollFrame;
+  bool mIgnoreRootScrollFrame;
 
   /// The number of mouse clicks.
   uint32_t clickCount;
 
   void AssignMouseEventData(const WidgetMouseEvent& aEvent, bool aCopyTargets)
   {
     AssignMouseEventBaseData(aEvent, aCopyTargets);
     AssignPointerHelperData(aEvent);
 
-    ignoreRootScrollFrame = aEvent.ignoreRootScrollFrame;
+    mIgnoreRootScrollFrame = aEvent.mIgnoreRootScrollFrame;
     clickCount = aEvent.clickCount;
   }
 
   /**
    * Returns true if the event is a context menu event caused by key.
    */
   bool IsContextMenuKeyEvent() const
   {

--- a/widget/android/nsWindow.cpp
+++ b/widget/android/nsWindow.cpp
@@ -1965,17 +1965,17 @@ nsWindow::OnContextmenuEvent(AndroidGeck
         pt = CSSPoint(points[0].x, points[0].y);
     }
 
     // Send the contextmenu event.
     WidgetMouseEvent contextMenuEvent(true, eContextMenu, this,
                                       WidgetMouseEvent::eReal, WidgetMouseEvent::eNormal);
     contextMenuEvent.mRefPoint =
         RoundedToInt(pt * GetDefaultScale()) - WidgetToScreenOffset();
-    contextMenuEvent.ignoreRootScrollFrame = true;
+    contextMenuEvent.mIgnoreRootScrollFrame = true;
     contextMenuEvent.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_TOUCH;
 
     nsEventStatus contextMenuStatus;
     DispatchEvent(&contextMenuEvent, contextMenuStatus);
 
     // If the contextmenu event was consumed (preventDefault issued), we follow with a
     // touchcancel event. This avoids followup touchend events passsing through and
     // triggering further element behaviour such as link-clicks.
@@ -2004,33 +2004,33 @@ nsWindow::OnLongTapEvent(AndroidGeckoEve
     WidgetMouseEvent event(true, eMouseLongTap, this,
         WidgetMouseEvent::eReal, WidgetMouseEvent::eNormal);
     event.button = WidgetMouseEvent::eLeftButton;
     event.mRefPoint =
         RoundedToInt(pt * GetDefaultScale()) - WidgetToScreenOffset();
     event.clickCount = 1;
     event.mTime = ae->Time();
     event.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_TOUCH;
-    event.ignoreRootScrollFrame = true;
+    event.mIgnoreRootScrollFrame = true;
 
     DispatchEvent(&event);
 }
 
 void
 nsWindow::DispatchHitTest(const WidgetTouchEvent& aEvent)
 {
     if (aEvent.mMessage == eTouchStart && aEvent.mTouches.Length() == 1) {
         // Since touch events don't get retargeted by PositionedEventTargeting.cpp
         // code on Fennec, we dispatch a dummy mouse event that *does* get
         // retargeted. The Fennec browser.js code can use this to activate the
         // highlight element in case the this touchstart is the start of a tap.
         WidgetMouseEvent hittest(true, eMouseHitTest, this,
                                  WidgetMouseEvent::eReal);
         hittest.mRefPoint = aEvent.mTouches[0]->mRefPoint;
-        hittest.ignoreRootScrollFrame = true;
+        hittest.mIgnoreRootScrollFrame = true;
         hittest.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_TOUCH;
         nsEventStatus status;
         DispatchEvent(&hittest, status);
 
         if (mAPZEventState && hittest.hitCluster) {
             mAPZEventState->ProcessClusterHit();
         }
     }

--- a/widget/nsGUIEventIPC.h
+++ b/widget/nsGUIEventIPC.h
@@ -225,33 +225,33 @@ struct ParamTraits<mozilla::WidgetWheelE
 template<>
 struct ParamTraits<mozilla::WidgetMouseEvent>
 {
   typedef mozilla::WidgetMouseEvent paramType;
 
   static void Write(Message* aMsg, const paramType& aParam)
   {
     WriteParam(aMsg, static_cast<mozilla::WidgetMouseEventBase>(aParam));
-    WriteParam(aMsg, aParam.ignoreRootScrollFrame);
+    WriteParam(aMsg, aParam.mIgnoreRootScrollFrame);
     WriteParam(aMsg, static_cast<paramType::ReasonType>(aParam.mReason));
     WriteParam(aMsg, static_cast<paramType::ContextMenuTriggerType>(
                        aParam.mContextMenuTrigger));
     WriteParam(aMsg, static_cast<paramType::ExitFromType>(aParam.mExitFrom));
     WriteParam(aMsg, aParam.clickCount);
   }
 
   static bool Read(const Message* aMsg, void** aIter, paramType* aResult)
   {
     bool rv;
     paramType::ReasonType reason = 0;
     paramType::ContextMenuTriggerType contextMenuTrigger = 0;
     paramType::ExitFromType exitFrom = 0;
     rv = ReadParam(aMsg, aIter,
                    static_cast<mozilla::WidgetMouseEventBase*>(aResult)) &&
-         ReadParam(aMsg, aIter, &aResult->ignoreRootScrollFrame) &&
+         ReadParam(aMsg, aIter, &aResult->mIgnoreRootScrollFrame) &&
          ReadParam(aMsg, aIter, &reason) &&
          ReadParam(aMsg, aIter, &contextMenuTrigger) &&
          ReadParam(aMsg, aIter, &exitFrom) &&
          ReadParam(aMsg, aIter, &aResult->clickCount);
     aResult->mReason = static_cast<paramType::Reason>(reason);
     aResult->mContextMenuTrigger =
       static_cast<paramType::ContextMenuTrigger>(contextMenuTrigger);
     aResult->mExitFrom = static_cast<paramType::ExitFrom>(exitFrom);