Change hover element to scrollbar's parent when hit test contains scrollbar

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 987f43e2c966951bc6e1f3cf4a3d0644d1e95c0b..1fc56067385a9dc46092084d1601a3e77f06dc4c 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -6088,14 +6088,22 @@ void Document::updateHoverActiveState(const HitTestRequest& request,
                                       Scrollbar* hitScrollbar) {
   DCHECK(!request.readOnly());
 
-  // Only cancel hover state when hitting native scrollbar because custom
-  // scrollbar's style depends on the owner element's hover state.
-  bool hitNativeScrollbar = hitScrollbar && !hitScrollbar->isCustomScrollbar();
-
-  if (request.active() && m_frame && !hitNativeScrollbar)
+  if (request.active() && m_frame)
     m_frame->eventHandler().notifyElementActivated();
 
-  Element* innerElementInDocument = hitNativeScrollbar ? nullptr : innerElement;
+  Element* innerElementInDocument = hitScrollbar ? nullptr : innerElement;
+  // Replace the innerElementInDocument to be srollbar's parent when hit
+  // scrollbar
+  if (hitScrollbar) {
+    ScrollableArea* scrollableArea = hitScrollbar->getScrollableArea();
+    if (scrollableArea && scrollableArea->layoutBox() &&
+        scrollableArea->layoutBox()->node() &&
+        scrollableArea->layoutBox()->node()->isElementNode()) {
+      innerElementInDocument =

[bokan, 2017/02/02 23:29:26]

You've confirmed that this preserves the hover effect for custom scrollbars?

[chaopeng, 2017/02/03 01:12:05]

Yes, the customer scrollbar issue is also cause by scrollbar depends on it's
parent's hover state.

+          toElement(hitScrollbar->getScrollableArea()->layoutBox()->node());
+    }
+  }
+
   while (innerElementInDocument && innerElementInDocument->document() != this) {
     innerElementInDocument->document().updateHoverActiveState(
         request, innerElementInDocument, hitScrollbar);
@@ -6104,7 +6112,7 @@ void Document::updateHoverActiveState(const HitTestRequest& request,
 
   updateDistribution();
   Element* oldActiveElement = activeHoverElement();
-  if (oldActiveElement && (!request.active() || hitNativeScrollbar)) {
+  if (oldActiveElement && !request.active()) {
     // The oldActiveElement layoutObject is null, dropped on :active by setting
     // display: none, for instance. We still need to clear the ActiveChain as
     // the mouse is released.