Coalesce async touch move events until the ack back from render

content/common/input/web_input_event_traits.h

Index: content/common/input/web_input_event_traits.h
diff --git a/content/common/input/web_input_event_traits.h b/content/common/input/web_input_event_traits.h
index 2e5a20edf435c05b5e71e6c7e243766b0cee2058..b8302f021d58d28948f9811fee9586f5f4f1e238 100644
--- a/content/common/input/web_input_event_traits.h
+++ b/content/common/input/web_input_event_traits.h
@@ -8,8 +8,12 @@
 #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 {
 
@@ -25,7 +29,10 @@ class CONTENT_EXPORT WebInputEventTraits {
                           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