Report accurate Overscroll on handleWheel.

Source/core/input/EventHandler.cpp

Index: Source/core/input/EventHandler.cpp
diff --git a/Source/core/input/EventHandler.cpp b/Source/core/input/EventHandler.cpp
index ed72ddf7134747ec0f7302532c2da5e16c164a68..2b1e20404e5a1d6134a5796865e02517a60d7731 100644
--- a/Source/core/input/EventHandler.cpp
+++ b/Source/core/input/EventHandler.cpp
@@ -1782,7 +1782,12 @@ bool EventHandler::handleWheelEvent(const PlatformWheelEvent& event)
     if (!view)
         return false;
 
-    if (view->scrollableArea()->handleWheel(event).didScroll())
+    ScrollResult scrollResult = view->scrollableArea()->handleWheel(event);
+#if defined(WTF_OS_MACOSX)

[bokan, 2015/06/23 16:20:45]

This should be based on a setting rather than an #ifdef and the setting should
be turned on only for Mac. #ifdefs make testing more complicated.

+    handleOverscroll(scrollResult);
+#endif
+
+    if (scrollResult.didScroll())
         RETURN_WHEEL_EVENT_HANDLED();
 
     return false;
@@ -2255,7 +2260,7 @@ void EventHandler::resetOverscroll(bool didScrollX, bool didScrollY)
         m_accumulatedRootOverscroll.setHeight(0);
 }
 
-void EventHandler::handleOverscroll(const ScrollResult& scrollResult, const PlatformGestureEvent& gestureEvent)
+void EventHandler::handleOverscroll(const ScrollResult& scrollResult, const FloatPoint& position, const FloatSize& velocity)
 {
     if (m_frame->isMainFrame() && m_frame->view() && m_frame->view()->scrollableArea()) {
         ScrollableArea* scrollablearea = m_frame->view()->scrollableArea();
@@ -2264,8 +2269,6 @@ void EventHandler::handleOverscroll(const ScrollResult& scrollResult, const Plat
         resetOverscroll(scrollResult.didScrollX, scrollResult.didScrollY);
         if (unusedDelta != FloatSize()) {
             m_accumulatedRootOverscroll += unusedDelta;
-            FloatPoint position = FloatPoint(gestureEvent.position().x(), gestureEvent.position().y());
-            FloatSize velocity = FloatSize(gestureEvent.velocityX(), gestureEvent.velocityY());
             m_frame->chromeClient().didOverscroll(unusedDelta, m_accumulatedRootOverscroll, position, velocity);
         }
     }
@@ -2354,7 +2357,9 @@ bool EventHandler::handleGestureScrollUpdate(const PlatformGestureEvent& gesture
 
     // Try to scroll the frame view.
     ScrollResult scrollResult = m_frame->applyScrollDelta(delta, false);
-    handleOverscroll(scrollResult, gestureEvent);
+    FloatPoint position = FloatPoint(gestureEvent.position().x(), gestureEvent.position().y());
+    FloatSize velocity = FloatSize(gestureEvent.velocityX(), gestureEvent.velocityY());
+    handleOverscroll(scrollResult, position, velocity);
     if (scrollResult.didScroll()) {
         setFrameWasScrolledByUser();
         return true;