Add UMA/Telemetry stats for touch event latency

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 965d0d61f7f71c26f3a7504ab164ca9f42b02bde..b862819278d9145260d8c5bcb64e658fde031ebf 100644
--- a/ui/base/latency_info.h
+++ b/ui/base/latency_info.h
@@ -63,6 +63,13 @@ struct UI_EXPORT LatencyInfo {
                                      base::TimeTicks time,
                                      uint32 event_count);
 
+  // Returns true if the a component with |type| and |id| is found in
+  // the latency_components and the component is stored to |output|.
+  // Returns false if no such component is found.
+  bool FindLatency(LatencyComponentType type,

[sadrul, 2013/06/27 17:44:01]

Merge this with HasLatency

[Yufeng Shen (Slow to review), 2013/06/27 19:01:03]

Done.

+                   int64 id,
+                   LatencyComponent* output) const;
+
   void Clear();
 
   LatencyMap latency_components;