Coalesce async touch move events until the ack back from render

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 <string>
 
 #include "base/basictypes.h"
+#include "content/common/input/did_overscroll_params.h"
+#include "content/common/input/input_event_ack_state.h"
 #include "content/common/input/scoped_web_input_event.h"
+#include "ipc/ipc_message.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
+#include "ui/events/latency_info.h"
 
 namespace content {
 
 // Utility class for performing operations on and with WebInputEvents.
 class CONTENT_EXPORT WebInputEventTraits {
  public:
   static const char* GetName(blink::WebInputEvent::Type type);
   static std::string ToString(const blink::WebInputEvent& event);
   static size_t GetSize(blink::WebInputEvent::Type type);
   static ScopedWebInputEvent Clone(const blink::WebInputEvent& event);
   static void Delete(blink::WebInputEvent* event);
   static bool CanCoalesce(const blink::WebInputEvent& event_to_coalesce,
                           const blink::WebInputEvent& event);
   static void Coalesce(const blink::WebInputEvent& event_to_coalesce,
                        blink::WebInputEvent* event);
-  static bool IgnoresAckDisposition(const blink::WebInputEvent& event);
+  static bool WillReceiveAckFromRenderer(const blink::WebInputEvent& event);
+
+  // Return uniqueTouchEventId for WebTouchEvent, otherwise return 0.
+  static uint32 GetUniqueTouchEventId(const blink::WebInputEvent& event);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_INPUT_WEB_INPUT_EVENT_TRAITS_H_