Add UMA/Telemetry stats for touch event latency

ui/base/latency_info.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/latency_info.h"
 
 #include <algorithm>
 
 namespace ui {
 
@@ skipping 45 matching lines @@
         new_count;
     it->second.event_count = new_count;
   }
 }
 
 void LatencyInfo::Clear() {
   latency_components.clear();
 }
 
 }  // namespace ui
-