Stop retrieving scrolling element id from the CompositorElementId.

third_party/WebKit/Source/core/page/scrolling/ScrollState.cpp

Index: third_party/WebKit/Source/core/page/scrolling/ScrollState.cpp
diff --git a/third_party/WebKit/Source/core/page/scrolling/ScrollState.cpp b/third_party/WebKit/Source/core/page/scrolling/ScrollState.cpp
index a4dfdf425f2be3b0049e0a4a6be8c678095f5022..e428017bd474baf1897d20bc9141cf97e81d9300 100644
--- a/third_party/WebKit/Source/core/page/scrolling/ScrollState.cpp
+++ b/third_party/WebKit/Source/core/page/scrolling/ScrollState.cpp
@@ -92,22 +92,18 @@ void ScrollState::ConsumeDeltaNative(double x, double y) {
     data_->delta_consumed_for_scroll_sequence = true;
 }
 
-Element* ScrollState::CurrentNativeScrollingElement() const {
-  uint64_t dom_node_id =
-      IdFromCompositorElementId(data_->current_native_scrolling_element());
-  if (dom_node_id == kInvalidDOMNodeId)
+Element* ScrollState::CurrentNativeScrollingElement() {
+  if (data_->current_native_scrolling_element() == CompositorElementId()) {
+    element_.Clear();

[pdr., 2017/05/17 00:24:19]

Instead of clearing element_ in the getter, can you clear it in
SetCurrentNativeScrollingElement?

     return nullptr;
-  return ElementForId(dom_node_id);
+  }
+  return element_;
 }
 
 void ScrollState::SetCurrentNativeScrollingElement(Element* element) {
+  element_ = element;
   data_->set_current_native_scrolling_element(CompositorElementIdFromDOMNodeId(
       DOMNodeIds::IdForNode(element), CompositorElementIdNamespace::kScroll));
 }
 
-void ScrollState::SetCurrentNativeScrollingElementById(int element_id) {
-  data_->set_current_native_scrolling_element(CompositorElementIdFromDOMNodeId(
-      element_id, CompositorElementIdNamespace::kScroll));
-}
-
 }  // namespace blink