MouseWheelEventQueue sends scrollEnd right away when latching is disabled.

content/browser/renderer_host/input/mock_input_ack_handler.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_INPUT_MOCK_INPUT_ACK_HANDLER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_MOCK_INPUT_ACK_HANDLER_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 37 matching lines @@
   void set_followup_touch_event(
       std::unique_ptr<TouchEventWithLatencyInfo> event) {
     touch_followup_event_ = std::move(event);
   }
 
   bool unexpected_event_ack_called() const {
     return unexpected_event_ack_called_;
   }
   InputEventAckState ack_state() const { return ack_state_; }
 
+  InputEventAckState acked_wheel_event_state() const {
+    return acked_wheel_event_state_;
+  }
+
   blink::WebInputEvent::Type ack_event_type() const { return ack_event_type_; }
 
   const NativeWebKeyboardEvent& acked_keyboard_event() const {
     return *acked_key_event_;
   }
   const blink::WebMouseWheelEvent& acked_wheel_event() const {
     return acked_wheel_event_;
   }
   const TouchEventWithLatencyInfo& acked_touch_event() const {
     return acked_touch_event_;
   }
   const blink::WebGestureEvent& acked_gesture_event() const {
     return acked_gesture_event_;
   }
 
  private:
   void RecordAckCalled(blink::WebInputEvent::Type eventType,
                        InputEventAckState ack_result);
 
   InputRouter* input_router_;
 
   size_t ack_count_;
   bool unexpected_event_ack_called_;
   blink::WebInputEvent::Type ack_event_type_;
   InputEventAckState ack_state_;
+  InputEventAckState acked_wheel_event_state_;
   std::unique_ptr<NativeWebKeyboardEvent> acked_key_event_;
   blink::WebMouseWheelEvent acked_wheel_event_;
   TouchEventWithLatencyInfo acked_touch_event_;
   blink::WebGestureEvent acked_gesture_event_;
   blink::WebMouseEvent acked_mouse_event_;
 
   std::unique_ptr<GestureEventWithLatencyInfo> gesture_followup_event_;
   std::unique_ptr<TouchEventWithLatencyInfo> touch_followup_event_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_MOCK_INPUT_ACK_HANDLER_H_