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 925583bf4ee1157d9bd1b9828cda54672eb71a64..cd2acf5f0b1cd760173a43377b5dade9f2ccd23f 100644
--- a/Source/core/page/scrolling/ScrollingCoordinator.h
+++ b/Source/core/page/scrolling/ScrollingCoordinator.h
@@ -96,12 +96,18 @@ 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*);
 
@@ -125,7 +131,8 @@ 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>);
@@ -136,6 +143,7 @@ private:
     ScrollbarMap m_horizontalScrollbars;
     ScrollbarMap m_verticalScrollbars;
 
+    HashSet<TouchEventTargetRectsObserver*> m_touchEventTargetRectsObservers;
 };
 
 } // namespace WebCore