diff --git a/widget/windows/nsWindow.cpp b/widget/windows/nsWindow.cpp
index 6192bf44a2c0..246d1ffe535d 100644
--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -186,6 +186,9 @@
 #define SM_CONVERTIBLESLATEMODE 0x2003
 #endif
 
+#include "mozilla/layers/CompositorParent.h"
+#include "InputData.h"
+
 using namespace mozilla;
 using namespace mozilla::dom;
 using namespace mozilla::gfx;
@@ -3736,10 +3739,50 @@ bool nsWindow::DispatchKeyboardEvent(WidgetGUIEvent* event)
   return ConvertStatus(status);
 }
 
-bool nsWindow::DispatchScrollEvent(WidgetGUIEvent* event)
+nsEventStatus nsWindow::MaybeDispatchAsyncWheelEvent(WidgetGUIEvent* aEvent)
 {
+  if (aEvent->mClass != eWheelEventClass) {
+    return nsEventStatus_eIgnore;
+  }
+
+  WidgetWheelEvent* event = aEvent->AsWheelEvent();
+
+  // Otherwise, scroll-zoom won't work.
+  if (event->IsControl()) {
+    return nsEventStatus_eIgnore;
+  }
+
+
+  // Other scrolling modes aren't supported yet.
+  if (event->deltaMode != nsIDOMWheelEvent::DOM_DELTA_LINE) {
+    return nsEventStatus_eIgnore;
+  }
+
+  ScrollWheelInput::ScrollMode scrollMode = ScrollWheelInput::SCROLLMODE_INSTANT;
+  if (Preferences::GetBool("general.smoothScroll"))
+    scrollMode = ScrollWheelInput::SCROLLMODE_SMOOTH;
+
+  ScreenPoint origin(event->refPoint.x, event->refPoint.y);
+  ScrollWheelInput input(event->time, event->timeStamp, 0,
+                         scrollMode,
+                         ScrollWheelInput::SCROLLDELTA_LINE,
+                         origin,
+                         event->lineOrPageDeltaX,
+                         event->lineOrPageDeltaY);
+
+  ScrollableLayerGuid ignoreGuid;
+  return mAPZC->ReceiveInputEvent(input, &ignoreGuid, nullptr);
+}
+
+bool nsWindow::DispatchScrollEvent(WidgetGUIEvent* aEvent)
+{
+  if (mAPZC) {
+    if (MaybeDispatchAsyncWheelEvent(aEvent) == nsEventStatus_eConsumeNoDefault)
+      return true;
+  }
+
   nsEventStatus status;
-  DispatchEvent(event, status);
+  DispatchEvent(aEvent, status);
   return ConvertStatus(status);
 }
 
@@ -7672,6 +7715,19 @@ void nsWindow::PickerClosed()
   }
 }
 
+CompositorParent* nsWindow::NewCompositorParent(int aSurfaceWidth,
+                                                int aSurfaceHeight)
+{
+  CompositorParent *compositor = new CompositorParent(this, false, aSurfaceWidth, aSurfaceHeight);
+
+  if (gfxPrefs::AsyncPanZoomEnabled()) {
+    mAPZC = CompositorParent::GetAPZCTreeManager(compositor->RootLayerTreeId());
+    APZCTreeManager::SetDPI(GetDPI());
+  }
+
+  return compositor;
+}
+
 /**************************************************************
  **************************************************************
  **
diff --git a/widget/windows/nsWindow.h b/widget/windows/nsWindow.h
index 872ab8828254..3d95f49c0c34 100644
--- a/widget/windows/nsWindow.h
+++ b/widget/windows/nsWindow.h
@@ -40,10 +40,9 @@
 #endif
 
 #include "nsUXThemeData.h"
-
 #include "nsIDOMMouseEvent.h"
-
 #include "nsIIdleServiceInternal.h"
+#include "mozilla/layers/APZCTreeManager.h"
 
 /**
  * Forward class definitions
@@ -75,6 +74,8 @@ class nsWindow : public nsWindowBase
   typedef mozilla::widget::TaskbarWindowPreview TaskbarWindowPreview;
   typedef mozilla::widget::NativeKey NativeKey;
   typedef mozilla::widget::MSGResult MSGResult;
+  typedef mozilla::layers::APZCTreeManager APZCTreeManager;
+
 public:
   nsWindow();
 
@@ -90,6 +91,7 @@ public:
   virtual bool DispatchScrollEvent(mozilla::WidgetGUIEvent* aEvent) MOZ_OVERRIDE;
   virtual nsWindowBase* GetParentWindowBase(bool aIncludeOwner) MOZ_OVERRIDE;
   virtual bool IsTopLevelWidget() MOZ_OVERRIDE { return mIsTopWidgetWindow; }
+  virtual CompositorParent* NewCompositorParent(int aSurfaceWidth, int aSurfaceHeight) MOZ_OVERRIDE;
 
   // nsIWidget interface
   NS_IMETHOD              Create(nsIWidget *aParent,
@@ -390,6 +392,8 @@ protected:
   void                    OnWindowPosChanging(LPWINDOWPOS& info);
   void                    OnSysColorChanged();
 
+  nsEventStatus           MaybeDispatchAsyncWheelEvent(mozilla::WidgetGUIEvent* aEvent);
+
   /**
    * Function that registers when the user has been active (used for detecting
    * when the user is idle).
@@ -591,6 +595,8 @@ protected:
 
   static bool sNeedsToInitMouseWheelSettings;
   static void InitMouseWheelScrollData();
+
+  nsRefPtr<APZCTreeManager> mAPZC;
 };
 
 /**