Amortize data usage using TrafficStats on Android.

components/data_usage/android/traffic_stats_amortizer.h

+// Copyright 2015 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 COMPONENTS_DATA_USAGE_ANDROID_TRAFFIC_STATS_AMORTIZER_H_
+#define COMPONENTS_DATA_USAGE_ANDROID_TRAFFIC_STATS_AMORTIZER_H_
+
+#include <stdint.h>
+
+#include <vector>
+
+#include "base/macros.h"
+#include "base/threading/thread_checker.h"
+#include "components/data_usage/core/data_use.h"
+#include "components/data_usage/core/data_use_amortizer.h"
+
+namespace data_usage {
+namespace android {
+
+// Class that uses Android TrafficStats to amortize the data usage stats
+// produced by the network stack. Should only be used on the IO thread.
+class TrafficStatsAmortizer : public DataUseAmortizer {
+ public:
+  TrafficStatsAmortizer();
+  ~TrafficStatsAmortizer() override;
+
+  void Amortize(std::vector<DataUse>* data_use_sequence,
+                int64_t extra_tx_bytes,
+                int64_t extra_rx_bytes) override;
+
+ protected:
+  // Virtual for testing.
+  virtual bool GetTrafficStatsTxBytes(int64_t* tx_bytes) const;
+  // Virtual for testing.
+  virtual bool GetTrafficStatsRxBytes(int64_t* rx_bytes) const;
+
+ private:
+  void RefreshTrafficStats();
+
+  base::ThreadChecker thread_checker_;
+
+  // Indicates whether or not |traffic_stats_tx_bytes_| and
+  // |traffic_stats_rx_bytes_| were available the last time they were refreshed.
+  bool are_traffic_stats_available_;

[bengr, 2015/10/12 21:33:08]

were_... ?

+
+  int64_t traffic_stats_tx_bytes_;
+  int64_t traffic_stats_rx_bytes_;
+
+  DISALLOW_COPY_AND_ASSIGN(TrafficStatsAmortizer);
+};
+
+}  // namespace android
+}  // namespace data_usage
+
+#endif  // COMPONENTS_DATA_USAGE_ANDROID_TRAFFIC_STATS_AMORTIZER_H_