Rework compositor touch hit testing

Source/core/page/scrolling/ScrollingCoordinator.h

Index: Source/core/page/scrolling/ScrollingCoordinator.h
diff --git a/Source/core/page/scrolling/ScrollingCoordinator.h b/Source/core/page/scrolling/ScrollingCoordinator.h
index c446d3689b4dc32f4bc8425bc3d7067e927026c8..0f3f43fb0d46f1585b0f473e4d6c1b69275a9e47 100644
--- a/Source/core/page/scrolling/ScrollingCoordinator.h
+++ b/Source/core/page/scrolling/ScrollingCoordinator.h
@@ -98,12 +98,18 @@ public:
     void updateLayerPositionConstraint(RenderLayer*);
     void touchEventTargetRectsDidChange(const Document*);
 
-    void computeAbsoluteTouchEventTargetRects(const Document*, Vector<IntRect>&);
-
     static String mainThreadScrollingReasonsAsText(MainThreadScrollingReasons);
     String mainThreadScrollingReasonsAsText() const;
     Region computeShouldHandleScrollGestureOnMainThreadRegion(const Frame*, const IntPoint& frameLocation) const;
 
+    class TouchEventTargetRectsObserver {
+    public:
+        virtual void touchEventTargetRectsChanged(const LayerHitTestRects&) = 0;
+    };
+
+    void addTouchEventTargetRectsObserver(TouchEventTargetRectsObserver*);
+    void removeTouchEventTargetRectsObserver(TouchEventTargetRectsObserver*);
+
 protected:
     explicit ScrollingCoordinator(Page*);
 
@@ -128,7 +134,8 @@ private:
     static WebKit::WebLayer* scrollingWebLayerForScrollableArea(ScrollableArea*);
 
     void setShouldHandleScrollGestureOnMainThreadRegion(const Region&);
-    void setTouchEventTargetRects(const Vector<IntRect>&);
+    void setTouchEventTargetRects(const LayerHitTestRects&);
+    void computeTouchEventTargetRects(LayerHitTestRects&);
     void setWheelEventHandlerCount(unsigned);
 
     WebKit::WebScrollbarLayer* addWebScrollbarLayer(ScrollableArea*, ScrollbarOrientation, PassOwnPtr<WebKit::WebScrollbarLayer>);
@@ -139,6 +146,7 @@ private:
     ScrollbarMap m_horizontalScrollbars;
     ScrollbarMap m_verticalScrollbars;
 
+    HashSet<TouchEventTargetRectsObserver*> m_touchEventTargetRectsObservers;
 };
 
 } // namespace WebCore