--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -4114,17 +4114,17 @@ ScrollFrameHelper::FireScrollPortEvent()
   if (!vertChanged && !horizChanged) {
     return NS_OK;
   }
 
   // If both either overflowed or underflowed then we dispatch only one
   // DOM event.
   bool both = vertChanged && horizChanged &&
                 newVerticalOverflow == newHorizontalOverflow;
-  InternalScrollPortEvent::orientType orient;
+  InternalScrollPortEvent::OrientType orient;
   if (both) {
     orient = InternalScrollPortEvent::both;
     mHorizontalOverflow = newHorizontalOverflow;
     mVerticalOverflow = newVerticalOverflow;
   }
   else if (vertChanged) {
     orient = InternalScrollPortEvent::vertical;
     mVerticalOverflow = newVerticalOverflow;

--- a/widget/ContentEvents.h
+++ b/widget/ContentEvents.h
@@ -26,17 +26,17 @@ namespace mozilla {
 class InternalScrollPortEvent : public WidgetGUIEvent
 {
 public:
   virtual InternalScrollPortEvent* AsScrollPortEvent() override
   {
     return this;
   }
 
-  enum orientType
+  enum OrientType
   {
     vertical   = 0,
     horizontal = 1,
     both       = 2
   };
 
   InternalScrollPortEvent(bool aIsTrusted, EventMessage aMessage,
                           nsIWidget* aWidget)
@@ -52,17 +52,17 @@ public:
     // Not copying widget, it is a weak reference.
     InternalScrollPortEvent* result =
       new InternalScrollPortEvent(false, mMessage, nullptr);
     result->AssignScrollPortEventData(*this, true);
     result->mFlags = mFlags;
     return result;
   }
 
-  orientType orient;
+  OrientType orient;
 
   void AssignScrollPortEventData(const InternalScrollPortEvent& aEvent,
                                  bool aCopyTargets)
   {
     AssignGUIEventData(aEvent, aCopyTargets);
 
     orient = aEvent.orient;
   }