Send input event's LatencyInfo back from renderer to browser when acked

ui/base/latency_info.h

Index: ui/base/latency_info.h
diff --git a/ui/base/latency_info.h b/ui/base/latency_info.h
index 9c6846562201dc64deebff5cdd72d87733e3c766..3482a500a8d0d85a89a5e92d92e7faf14f0be34e 100644
--- a/ui/base/latency_info.h
+++ b/ui/base/latency_info.h
@@ -59,6 +59,9 @@ struct UI_EXPORT LatencyInfo {
   // Merges the contents of another LatencyInfo into this one.
   void MergeWith(const LatencyInfo& other);
 
+  // Add LatencyComponents that are in |other| but not in |this|.
+  void AddNewLatencyFrom(const LatencyInfo& other);
+
   // Modifies the current sequence number for a component, and adds a new
   // sequence number with the current timestamp.
   void AddLatencyNumber(LatencyComponentType component,