--- a/dom/base/nsDOMWindowUtils.cpp
+++ b/dom/base/nsDOMWindowUtils.cpp
@@ -763,17 +763,18 @@ nsDOMWindowUtils::SendPointerEventCommon
   event.buttons = nsContentUtils::GetButtonsFlagForButton(aButton);
   event.pressure = aPressure;
   event.inputSource = aInputSourceArg;
   event.pointerId = aPointerId;
   event.mWidth = aWidth;
   event.mHeight = aHeight;
   event.tiltX = aTiltX;
   event.tiltY = aTiltY;
-  event.isPrimary = (nsIDOMMouseEvent::MOZ_SOURCE_MOUSE == aInputSourceArg) ? true : aIsPrimary;
+  event.mIsPrimary =
+    (nsIDOMMouseEvent::MOZ_SOURCE_MOUSE == aInputSourceArg) ? true : aIsPrimary;
   event.mClickCount = aClickCount;
   event.mTime = PR_IntervalNow();
   event.mFlags.mIsSynthesizedForTests = aOptionalArgCount >= 10 ? aIsSynthesized : true;
 
   nsPresContext* presContext = GetPresContext();
   if (!presContext) {
     return NS_ERROR_FAILURE;
   }

--- a/dom/events/EventStateManager.cpp
+++ b/dom/events/EventStateManager.cpp
@@ -3829,17 +3829,17 @@ CreateMouseOrPointerWidgetEvent(WidgetMo
   if (sourcePointer) {
     PROFILER_LABEL("Input", "DispatchPointerEvent",
       js::ProfileEntry::Category::EVENTS);
 
     nsAutoPtr<WidgetPointerEvent> newPointerEvent;
     newPointerEvent =
       new WidgetPointerEvent(aMouseEvent->IsTrusted(), aMessage,
                              aMouseEvent->mWidget);
-    newPointerEvent->isPrimary = sourcePointer->isPrimary;
+    newPointerEvent->mIsPrimary = sourcePointer->mIsPrimary;
     newPointerEvent->pointerId = sourcePointer->pointerId;
     newPointerEvent->mWidth = sourcePointer->mWidth;
     newPointerEvent->mHeight = sourcePointer->mHeight;
     newPointerEvent->inputSource = sourcePointer->inputSource;
     newPointerEvent->relatedTarget =
       nsIPresShell::GetPointerCapturingContent(sourcePointer->pointerId)
         ? nullptr
         : aRelatedContent;

--- a/dom/events/PointerEvent.cpp
+++ b/dom/events/PointerEvent.cpp
@@ -88,17 +88,17 @@ PointerEvent::Constructor(EventTarget* a
   WidgetPointerEvent* widgetEvent = e->mEvent->AsPointerEvent();
   widgetEvent->pointerId = aParam.mPointerId;
   widgetEvent->mWidth = aParam.mWidth;
   widgetEvent->mHeight = aParam.mHeight;
   widgetEvent->pressure = aParam.mPressure;
   widgetEvent->tiltX = aParam.mTiltX;
   widgetEvent->tiltY = aParam.mTiltY;
   widgetEvent->inputSource = ConvertStringToPointerType(aParam.mPointerType);
-  widgetEvent->isPrimary = aParam.mIsPrimary;
+  widgetEvent->mIsPrimary = aParam.mIsPrimary;
   widgetEvent->buttons = aParam.mButtons;
 
   e->SetTrusted(trusted);
   return e.forget();
 }
 
 // static
 already_AddRefed<PointerEvent>
@@ -151,17 +151,17 @@ int32_t
 PointerEvent::TiltY()
 {
   return mEvent->AsPointerEvent()->tiltY;
 }
 
 bool
 PointerEvent::IsPrimary()
 {
-  return mEvent->AsPointerEvent()->isPrimary;
+  return mEvent->AsPointerEvent()->mIsPrimary;
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 

--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -6825,39 +6825,44 @@ nsIPresShell::GetPointerInfo(uint32_t aP
 void
 PresShell::UpdateActivePointerState(WidgetGUIEvent* aEvent)
 {
   switch (aEvent->mMessage) {
   case eMouseEnterIntoWidget:
     // In this case we have to know information about available mouse pointers
     if (WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent()) {
       gActivePointersIds->Put(mouseEvent->pointerId,
-                              new PointerInfo(false, mouseEvent->inputSource, true));
+                              new PointerInfo(false, mouseEvent->inputSource,
+                                              true));
     }
     break;
   case ePointerDown:
     // In this case we switch pointer to active state
     if (WidgetPointerEvent* pointerEvent = aEvent->AsPointerEvent()) {
       gActivePointersIds->Put(pointerEvent->pointerId,
-                              new PointerInfo(true, pointerEvent->inputSource, pointerEvent->isPrimary));
+                              new PointerInfo(true, pointerEvent->inputSource,
+                                              pointerEvent->mIsPrimary));
     }
     break;
   case ePointerUp:
     // In this case we remove information about pointer or turn off active state
     if (WidgetPointerEvent* pointerEvent = aEvent->AsPointerEvent()) {
       if(pointerEvent->inputSource != nsIDOMMouseEvent::MOZ_SOURCE_TOUCH) {
         gActivePointersIds->Put(pointerEvent->pointerId,
-                                new PointerInfo(false, pointerEvent->inputSource, pointerEvent->isPrimary));
+                                new PointerInfo(false,
+                                                pointerEvent->inputSource,
+                                                pointerEvent->mIsPrimary));
       } else {
         gActivePointersIds->Remove(pointerEvent->pointerId);
       }
     }
     break;
   case eMouseExitFromWidget:
-    // In this case we have to remove information about disappeared mouse pointers
+    // In this case we have to remove information about disappeared mouse
+    // pointers
     if (WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent()) {
       gActivePointersIds->Remove(mouseEvent->pointerId);
     }
     break;
   default:
     break;
   }
 }
@@ -7191,17 +7196,17 @@ DispatchPointerFromMouseOrTouch(PresShel
     for (uint32_t i = 0; i < touchEvent->mTouches.Length(); ++i) {
       mozilla::dom::Touch* touch = touchEvent->mTouches[i];
       if (!touch || !touch->convertToPointer) {
         continue;
       }
 
       WidgetPointerEvent event(touchEvent->IsTrusted(), pointerMessage,
                                touchEvent->mWidget);
-      event.isPrimary = i == 0;
+      event.mIsPrimary = i == 0;
       event.pointerId = touch->Identifier();
       event.mRefPoint = touch->mRefPoint;
       event.mModifiers = touchEvent->mModifiers;
       event.mWidth = touch->RadiusX();
       event.mHeight = touch->RadiusY();
       event.tiltX = touch->tiltX;
       event.tiltY = touch->tiltY;
       event.mTime = touchEvent->mTime;

--- a/widget/MouseEvents.h
+++ b/widget/MouseEvents.h
@@ -663,36 +663,36 @@ private:
 class WidgetPointerEvent : public WidgetMouseEvent
 {
   friend class mozilla::dom::PBrowserParent;
   friend class mozilla::dom::PBrowserChild;
 
   WidgetPointerEvent()
     : mWidth(0)
     , mHeight(0)
-    , isPrimary(true)
+    , mIsPrimary(true)
   {
   }
 
 public:
   virtual WidgetPointerEvent* AsPointerEvent() override { return this; }
 
   WidgetPointerEvent(bool aIsTrusted, EventMessage aMsg, nsIWidget* w)
     : WidgetMouseEvent(aIsTrusted, aMsg, w, ePointerEventClass, eReal)
     , mWidth(0)
     , mHeight(0)
-    , isPrimary(true)
+    , mIsPrimary(true)
   {
   }
 
   explicit WidgetPointerEvent(const WidgetMouseEvent& aEvent)
     : WidgetMouseEvent(aEvent)
     , mWidth(0)
     , mHeight(0)
-    , isPrimary(true)
+    , mIsPrimary(true)
   {
     mClass = ePointerEventClass;
   }
 
   virtual WidgetEvent* Duplicate() const override
   {
     MOZ_ASSERT(mClass == ePointerEventClass,
                "Duplicate() must be overridden by sub class");
@@ -701,25 +701,25 @@ public:
       new WidgetPointerEvent(false, mMessage, nullptr);
     result->AssignPointerEventData(*this, true);
     result->mFlags = mFlags;
     return result;
   }
 
   uint32_t mWidth;
   uint32_t mHeight;
-  bool isPrimary;
+  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;
-    isPrimary = aEvent.isPrimary;
+    mIsPrimary = aEvent.mIsPrimary;
   }
 };
 
 } // namespace mozilla
 
 #endif // mozilla_MouseEvents_h__

--- a/widget/nsGUIEventIPC.h
+++ b/widget/nsGUIEventIPC.h
@@ -286,29 +286,29 @@ struct ParamTraits<mozilla::WidgetPointe
   static void Write(Message* aMsg, const paramType& aParam)
   {
     WriteParam(aMsg, static_cast<mozilla::WidgetMouseEvent>(aParam));
     WriteParam(aMsg, aParam.pointerId);
     WriteParam(aMsg, aParam.mWidth);
     WriteParam(aMsg, aParam.mHeight);
     WriteParam(aMsg, aParam.tiltX);
     WriteParam(aMsg, aParam.tiltY);
-    WriteParam(aMsg, aParam.isPrimary);
+    WriteParam(aMsg, aParam.mIsPrimary);
   }
 
   static bool Read(const Message* aMsg, PickleIterator* aIter, paramType* aResult)
   {
     bool rv =
       ReadParam(aMsg, aIter, static_cast<mozilla::WidgetMouseEvent*>(aResult)) &&
       ReadParam(aMsg, aIter, &aResult->pointerId) &&
       ReadParam(aMsg, aIter, &aResult->mWidth) &&
       ReadParam(aMsg, aIter, &aResult->mHeight) &&
       ReadParam(aMsg, aIter, &aResult->tiltX) &&
       ReadParam(aMsg, aIter, &aResult->tiltY) &&
-      ReadParam(aMsg, aIter, &aResult->isPrimary);
+      ReadParam(aMsg, aIter, &aResult->mIsPrimary);
     return rv;
   }
 };
 
 template<>
 struct ParamTraits<mozilla::WidgetTouchEvent>
 {
   typedef mozilla::WidgetTouchEvent paramType;