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

ui/base/latency_info.cc

Index: ui/base/latency_info.cc
diff --git a/ui/base/latency_info.cc b/ui/base/latency_info.cc
index 459fc2ab689a3183eede3c51a43042c2542a1c83..9551450fab5d592fdaa3d3c720c40cf48a13f1c0 100644
--- a/ui/base/latency_info.cc
+++ b/ui/base/latency_info.cc
@@ -26,6 +26,20 @@ void LatencyInfo::MergeWith(const LatencyInfo& other) {
   }
 }
 
+void LatencyInfo::AddNewLatencyFrom(const LatencyInfo& other) {
+    for (LatencyMap::const_iterator it = other.latency_components.begin();
+         it != other.latency_components.end();
+         ++it) {
+      if (!FindLatency(it->first.first, it->first.second, NULL)) {
+        AddLatencyNumberWithTimestamp(it->first.first,
+                                      it->first.second,
+                                      it->second.sequence_number,
+                                      it->second.event_time,
+                                      it->second.event_count);
+      }
+    }
+}
+
 void LatencyInfo::AddLatencyNumber(LatencyComponentType component,
                                    int64 id,
                                    int64 component_sequence_number) {