OverscrollGlow for mainThread-{BLINK CHANGES}

Source/core/page/EventHandler.cpp

Index: Source/core/page/EventHandler.cpp
diff --git a/Source/core/page/EventHandler.cpp b/Source/core/page/EventHandler.cpp
index dd3c5aee907340e0eb1b561e52fb6f57dfe5547c..dd2725de76e6fc6749908bd2c9e90031fe2ac2b9 100644
--- a/Source/core/page/EventHandler.cpp
+++ b/Source/core/page/EventHandler.cpp
@@ -233,6 +233,8 @@ EventHandler::EventHandler(LocalFrame* frame)
     , m_eventHandlerWillResetCapturingMouseEventsNode(0)
     , m_clickCount(0)
     , m_shouldOnlyFireDragOverEvent(false)
+    , m_unusedDelta(FloatPoint())
+    , m_accumulatedRootOverScroll(FloatPoint())
     , m_mousePositionIsUnknown(true)
     , m_mouseDownTimestamp(0)
     , m_widgetIsLatched(false)
@@ -926,10 +928,10 @@ void EventHandler::stopAutoscroll()
         controller->stopAutoscroll();
 }
 
-bool EventHandler::scroll(ScrollDirection direction, ScrollGranularity granularity, Node* startNode, Node** stopNode, float delta, IntPoint absolutePoint)
+ScrollResultOneDimensional EventHandler::scroll(ScrollDirection direction, ScrollGranularity granularity, Node* startNode, Node** stopNode, float delta, IntPoint absolutePoint)
 {
     if (!delta)
-        return false;
+        return ScrollResultOneDimensional(false);
 
     Node* node = startNode;
 
@@ -940,30 +942,31 @@ bool EventHandler::scroll(ScrollDirection direction, ScrollGranularity granulari
         node = m_mousePressNode.get();
 
     if (!node || !node->layoutObject())
-        return false;
+        return ScrollResultOneDimensional(false);
 
     bool rootLayerScrolls = m_frame->settings() && m_frame->settings()->rootLayerScrolls();
     LayoutBox* curBox = node->layoutObject()->enclosingBox();
+    ScrollResultOneDimensional result(false);
     while (curBox && (rootLayerScrolls || !curBox->isLayoutView())) {
         ScrollDirection physicalDirection = toPhysicalDirection(
             direction, curBox->isHorizontalWritingMode(), curBox->style()->isFlippedBlocksWritingMode());
 
         // If we're at the stopNode, we should try to scroll it but we shouldn't bubble past it
         bool shouldStopBubbling = stopNode && *stopNode && curBox->node() == *stopNode;
-        bool didScroll = curBox->scroll(physicalDirection, granularity, delta);
+        result = curBox->scroll(physicalDirection, granularity, delta);
 
-        if (didScroll && stopNode)
+        if (result.didScroll && stopNode)
             *stopNode = curBox->node();
 
-        if (didScroll || shouldStopBubbling) {
+        if (result.didScroll || shouldStopBubbling) {
             setFrameWasScrolledByUser();
-            return true;
+            return result;
         }
 
         curBox = curBox->containingBlock();
     }
 
-    return false;
+    return result;
 }
 
 void EventHandler::customizedScroll(const Node& startNode, ScrollState& scrollState)
@@ -983,7 +986,7 @@ bool EventHandler::bubblingScroll(ScrollDirection direction, ScrollGranularity g
     // here because of an onLoad event, in which case the final layout hasn't been performed yet.
     m_frame->document()->updateLayoutIgnorePendingStylesheets();
     // FIXME: enable scroll customization in this case. See crbug.com/410974.
-    if (scroll(direction, granularity, startingNode))
+    if (scroll(direction, granularity, startingNode).didScroll)
         return true;
     LocalFrame* frame = m_frame;
     FrameView* view = frame->view();
@@ -996,6 +999,16 @@ bool EventHandler::bubblingScroll(ScrollDirection direction, ScrollGranularity g
     return toLocalFrame(parentFrame)->eventHandler().bubblingScroll(direction, granularity, m_frame->deprecatedLocalOwner());
 }
 
+FloatPoint EventHandler::unusedDelta() const
+{
+    return m_unusedDelta;
+}
+
+FloatPoint EventHandler::accumulatedRootOverScroll() const
+{
+    return m_accumulatedRootOverScroll;
+}
+
 IntPoint EventHandler::lastKnownMousePosition() const
 {
     return m_lastKnownMousePosition;
@@ -2204,11 +2217,11 @@ void EventHandler::defaultWheelEventHandler(Node* startNode, WheelEvent* wheelEv
 
     // FIXME: enable scroll customization in this case. See crbug.com/410974.
     if (wheelEvent->railsMode() != Event::RailsModeVertical
-        && scroll(ScrollRight, granularity, startNode, &stopNode, wheelEvent->deltaX(), absolutePosition))
+        && scroll(ScrollRight, granularity, startNode, &stopNode, wheelEvent->deltaX(), absolutePosition).didScroll)
         wheelEvent->setDefaultHandled();
 
     if (wheelEvent->railsMode() != Event::RailsModeHorizontal
-        && scroll(ScrollDown, granularity, startNode, &stopNode, wheelEvent->deltaY(), absolutePosition))
+        && scroll(ScrollDown, granularity, startNode, &stopNode, wheelEvent->deltaY(), absolutePosition).didScroll)
         wheelEvent->setDefaultHandled();
 
     if (!m_latchedWheelEventNode)
@@ -2709,14 +2722,24 @@ bool EventHandler::handleGestureScrollUpdate(const PlatformGestureEvent& gesture
 
             // First try to scroll the closest scrollable LayoutBox ancestor of |node|.
             ScrollGranularity granularity = ScrollByPrecisePixel;
-            bool horizontalScroll = scroll(ScrollLeft, granularity, node, &stopNode, delta.width());
+            m_unusedDelta = FloatPoint();
+            ScrollResultOneDimensional result = scroll(ScrollLeft, granularity, node, &stopNode, delta.width());
+            bool horizontalScroll = result.didScroll;
+            if (m_frame->isMainFrame())
+                m_unusedDelta.setX(result.unusedScrollDelta);
             if (!gestureEvent.preventPropagation())
                 stopNode = nullptr;
-            bool verticalScroll = scroll(ScrollUp, granularity, node, &stopNode, delta.height());
+            result = scroll(ScrollUp, granularity, node, &stopNode, delta.height());
+            bool verticalScroll = result.didScroll;
+            if (m_frame->isMainFrame())
+                m_unusedDelta.setY(result.unusedScrollDelta);
             scrolled = horizontalScroll || verticalScroll;
 
             if (gestureEvent.preventPropagation())
                 m_previousGestureScrolledNode = stopNode;
+
+            if (m_frame->isMainFrame())
+                m_accumulatedRootOverScroll += m_unusedDelta;
         }
         if (scrolled) {
             setFrameWasScrolledByUser();
@@ -2742,6 +2765,7 @@ void EventHandler::clearGestureScrollNodes()
     m_previousGestureScrolledNode = nullptr;
     m_deltaConsumedForScrollSequence = false;
     m_currentScrollChain.clear();
+    m_accumulatedRootOverScroll = FloatPoint();
 }
 
 bool EventHandler::isScrollbarHandlingGestures() const
@@ -3625,7 +3649,7 @@ void EventHandler::defaultSpaceEventHandler(KeyboardEvent* event)
 
     ScrollDirection direction = event->shiftKey() ? ScrollBlockDirectionBackward : ScrollBlockDirectionForward;
     // FIXME: enable scroll customization in this case. See crbug.com/410974.
-    if (scroll(direction, ScrollByPage)) {
+    if (scroll(direction, ScrollByPage).didScroll) {
         event->setDefaultHandled();
         return;
     }