Expose scroll customization for touch to JS (behind REF).

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 188 matching lines @@
 {
     scrollChain.clear();
 
     ASSERT(startNode.layoutObject());
     LayoutBox* curBox = startNode.layoutObject()->enclosingBox();
 
     // Scrolling propagates along the containing block chain.
     while (curBox && !curBox->isLayoutView()) {
         Node* curNode = curBox->node();
         // FIXME: this should reject more elements, as part of crbug.com/410974.
-        if (curNode && curNode->isElementNode())
-            scrollChain.prepend(toElement(curNode));
+        if (curNode && curNode->isElementNode()) {
+            Element* curElement = toElement(curNode);
+            if (curElement == frame.document()->documentElement())

[Rick Byers, 2015/04/10 14:51:44]

why doesn't the documentElement get put on the scroll chain?  You can customize
both the documentElement and body, right?

[tdresser, 2015/05/08 18:23:02]

I've clarified this in a comment. This only matters in quirks mode.

+                break;
+            scrollChain.prepend(curElement);
+        }
         curBox = curBox->containingBlock();
     }
 
     // FIXME: we should exclude the document in some cases, as part
     // of crbug.com/410974.
     scrollChain.prepend(frame.document()->documentElement());
 }
 
 EventHandler::EventHandler(LocalFrame* frame)
     : m_frame(frame)
@@ skipping 83 matching lines @@
     m_lastMouseDownUserGestureToken.clear();
     m_mousePressNode = nullptr;
     m_mousePressed = false;
     m_capturesDragging = false;
     m_capturingMouseEventsNode = nullptr;
     m_latchedWheelEventNode = nullptr;
     m_previousWheelScrolledNode = nullptr;
     m_targetForTouchID.clear();
     m_touchSequenceDocument.clear();
     m_touchSequenceUserGestureToken.clear();
-    m_scrollGestureHandlingNode = nullptr;
+    clearGestureScrollState();
     m_lastGestureScrollOverWidget = false;
-    m_previousGestureScrolledNode = nullptr;
     m_scrollbarHandlingScrollGesture = nullptr;
     m_maxMouseMovedDuration = 0;
     m_touchPressed = false;
     m_mouseDownMayStartSelect = false;
     m_mouseDownMayStartDrag = false;
     m_lastShowPressTimestamp = 0;
     m_lastDeferredTapElement = nullptr;
     m_eventHandlerWillResetCapturingMouseEventsNode = false;
     m_mouseDownWasSingleClickInSelection = false;
     m_selectionInitiationState = HaveNotStartedSelection;
@@ skipping 2270 matching lines @@
     if (node) {
         passScrollGestureEventToWidget(gestureEvent, node->layoutObject());
         if (RuntimeEnabledFeatures::scrollCustomizationEnabled()) {
             RefPtrWillBeRawPtr<ScrollState> scrollState = ScrollState::create(
                 0, 0, 0, 0, 0, gestureEvent.inertial(), /* isBeginning */
                 false, /* isEnding */ true, /* fromUserInput */ true);
             customizedScroll(*node.get(), *scrollState);
         }
     }
 
-    clearGestureScrollNodes();
+    clearGestureScrollState();
     return false;
 }
 
 bool EventHandler::handleGestureScrollBegin(const PlatformGestureEvent& gestureEvent)
 {
     Document* document = m_frame->document();
     if (!document->layoutView())
         return false;
 
     FrameView* view = m_frame->view();
@@ skipping 106 matching lines @@
 
     // Try to scroll the frame view.
     if (m_frame->applyScrollDelta(delta, false)) {
         setFrameWasScrolledByUser();
         return true;
     }
 
     return false;
 }
 
-void EventHandler::clearGestureScrollNodes()
+void EventHandler::clearGestureScrollState()
 {
     m_scrollGestureHandlingNode = nullptr;
     m_previousGestureScrolledNode = nullptr;
     m_deltaConsumedForScrollSequence = false;
     m_currentScrollChain.clear();
 }
 
 bool EventHandler::isScrollbarHandlingGestures() const
 {
     return m_scrollbarHandlingScrollGesture.get();
@@ skipping 1331 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace blink