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..c6fa837d5ef754a786265e056a53ee48f855895f 100644
--- a/content/common/input/web_input_event_traits.h
+++ b/content/common/input/web_input_event_traits.h
@@ -25,7 +25,10 @@ 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