|  | // 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 BASE_METRICS_HISTOGRAM_FLATTENER_H_ | 
|  | #define BASE_METRICS_HISTOGRAM_FLATTENER_H_ | 
|  |  | 
|  | #include <map> | 
|  | #include <string> | 
|  |  | 
|  | #include "base/macros.h" | 
|  | #include "base/metrics/histogram.h" | 
|  |  | 
|  | namespace base { | 
|  |  | 
|  | class HistogramSamples; | 
|  |  | 
|  | // HistogramFlattener is an interface used by HistogramSnapshotManager, which | 
|  | // handles the logistics of gathering up available histograms for recording. | 
|  | class BASE_EXPORT HistogramFlattener { | 
|  | public: | 
|  | virtual void RecordDelta(const HistogramBase& histogram, | 
|  | const HistogramSamples& snapshot) = 0; | 
|  |  | 
|  | protected: | 
|  | HistogramFlattener() = default; | 
|  | virtual ~HistogramFlattener() = default; | 
|  |  | 
|  | private: | 
|  | DISALLOW_COPY_AND_ASSIGN(HistogramFlattener); | 
|  | }; | 
|  |  | 
|  | }  // namespace base | 
|  |  | 
|  | #endif  // BASE_METRICS_HISTOGRAM_FLATTENER_H_ |