Chrome Performance Monitor: Metric API Functions.

chrome/browser/performance_monitor/metric_details.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_PERFORMANCE_MONITOR_METRIC_DETAILS_H_
 #define CHROME_BROWSER_PERFORMANCE_MONITOR_METRIC_DETAILS_H_
 #pragma once
 
 #include <string>
 
 namespace performance_monitor {
 
+enum MetricType {
+  METRIC_SAMPLE,
+  METRIC_NUMBER_OF_METRICS
+};
+
+const char* MetricTypeToString(MetricType event_type);
+
 struct MetricDetails {
   MetricDetails();
   MetricDetails(const std::string& metric_name,
                 const std::string& metric_description);
   ~MetricDetails();
 
   std::string name;
   std::string description;
 };
 
 }  // namespace performance_monitor
 
 #endif  // CHROME_BROWSER_PERFORMANCE_MONITOR_METRIC_DETAILS_H_