Allow UmaHistogramEnumeration to be used with enum classes.

base/metrics/histogram_functions.h

 // Copyright 2016 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 BASE_METRICS_HISTOGRAM_FUNCTIONS_H_
 #define BASE_METRICS_HISTOGRAM_FUNCTIONS_H_
 
 #include "base/metrics/histogram.h"
 #include "base/metrics/histogram_base.h"
 #include "base/time/time.h"
@@ skipping 25 matching lines @@
 
 // For adding sample to enum histogram.
 // Sample usage:
 //   base::UmaHistogramEnumeration("My.Enumeration", VALUE, EVENT_MAX_VALUE);
 // Note that new Enum values can be added, but existing enums must never be
 // renumbered or deleted and reused.
 template <typename T>
 void UmaHistogramEnumeration(const std::string& name, T sample, T max) {
   static_assert(std::is_enum<T>::value,
                 "Non enum passed to UmaHistogramEnumeration");
-  return UmaHistogramExactLinear(name, static_cast<int>(sample), max);
+  return UmaHistogramExactLinear(name, static_cast<int>(sample),

[dcheng, 2017/04/05 17:12:13]

Nit: it might be nice to DCHECK that sample and max are in range of int.

[benwells, 2017/04/06 07:30:01]

Hmmm .... OK. Not the simplest nit I've seen, or maybe I'm being dumb.

+                                 static_cast<int>(max));
 }
 
 // For adding boolean sample to histogram.
 // Sample usage:
 //   base::UmaHistogramBoolean("My.Boolean", true)
 BASE_EXPORT void UmaHistogramBoolean(const std::string& name, bool sample);
 
 // For adding histogram with percent.
 // Percents are integer between 1 and 100.
 // Sample usage:
@@ skipping 34 matching lines @@
 
 // For recording memory related histograms.
 // Used to measure common KB-granularity memory stats. Range is up to 500M.
 BASE_EXPORT void UmaHistogramMemoryKB(const std::string& name, int sample);
 // Used to measure common MB-granularity memory stats. Range is up to ~64G.
 BASE_EXPORT void UmaHistogramMemoryLargeMB(const std::string& name, int sample);
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_FUNCTIONS_H_