Events ignoring ack disposition receive synthetic acks.

content/common/input/web_input_event_traits.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_COMMON_INPUT_WEB_INPUT_EVENT_TRAITS_H_
 #define CONTENT_COMMON_INPUT_WEB_INPUT_EVENT_TRAITS_H_
 
 #include "base/basictypes.h"
 #include "content/common/input/scoped_web_input_event.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 
 namespace content {
 
 // Utility class for performing operations on and with WebInputEvents.
 class WebInputEventTraits {
  public:
   static const char* GetName(WebKit::WebInputEvent::Type type);
   static size_t GetSize(WebKit::WebInputEvent::Type type);
   static ScopedWebInputEvent Clone(const WebKit::WebInputEvent& event);
   static void Delete(WebKit::WebInputEvent* event);
   static bool CanCoalesce(const WebKit::WebInputEvent& event_to_coalesce,
                           const WebKit::WebInputEvent& event);
   static void Coalesce(const WebKit::WebInputEvent& event_to_coalesce,
                        WebKit::WebInputEvent* event);
+  static bool IgnoresAckDisposition(WebKit::WebInputEvent::Type type);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_INPUT_WEB_INPUT_EVENT_TRAITS_H_