Coalesce async touch move events until the ack back from render

content/browser/renderer_host/input/input_router_impl.h

Index: content/browser/renderer_host/input/input_router_impl.h
diff --git a/content/browser/renderer_host/input/input_router_impl.h b/content/browser/renderer_host/input/input_router_impl.h
index ab5058329547e51cd7a443674d937d5109671aee..6a211426d1a1fcb07135f4f44394d25660ca0daf 100644
--- a/content/browser/renderer_host/input/input_router_impl.h
+++ b/content/browser/renderer_host/input/input_router_impl.h
@@ -19,6 +19,7 @@
 #include "content/public/browser/native_web_keyboard_event.h"
 
 struct InputHostMsg_HandleInputEvent_ACK_Params;
+struct InputHostMsg_HandleUncancelableTouchMoveEvent_ACK_Params;
 
 namespace IPC {
 class Sender;
@@ -125,6 +126,7 @@ private:
 
   // IPC message handlers
   void OnInputEventAck(const InputHostMsg_HandleInputEvent_ACK_Params& ack);
+  void OnUncancelableTouchMoveAck();
   void OnDidOverscroll(const DidOverscrollParams& params);
   void OnMsgMoveCaretAck();
   void OnSelectMessageAck();