currentlyscrollinglayer cleared in scrollAnimatedBegin.

ui/events/blink/input_handler_proxy.cc

Index: ui/events/blink/input_handler_proxy.cc
diff --git a/ui/events/blink/input_handler_proxy.cc b/ui/events/blink/input_handler_proxy.cc
index d12cbb0f2839f8c219d0a6c57b338c2cc77444eb..5cbb1cc9dc151d1cac73a8bb8cf4fb39632a7061 100644
--- a/ui/events/blink/input_handler_proxy.cc
+++ b/ui/events/blink/input_handler_proxy.cc
@@ -581,6 +581,7 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollBegin(
         &scroll_state, GestureScrollInputType(gesture_event.sourceDevice));
   } else if (ShouldAnimate(gesture_event.data.scrollBegin.deltaHintUnits !=
                            blink::WebGestureEvent::ScrollUnits::Pixels)) {
+    DCHECK(!scroll_state.is_in_inertial_phase());
     gfx::Point scroll_point(gesture_event.x, gesture_event.y);
     scroll_status = input_handler_->ScrollAnimatedBegin(scroll_point);
   } else {