Implement UMA log throttling for cellular connections

components/metrics/data_use_tracker.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 COMPONENTS_METRICS_DATA_USE_TRACKER_H_
+#define COMPONENTS_METRICS_DATA_USE_TRACKER_H_
+
+#include "base/callback.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
+
+namespace metrics {
+
+typedef base::Callback<void(const std::string&, int)>
+    UpdateUsagePrefCallbackType;
+
+// Records the data use of user traffic and UMA traffic in user prefs. Taking
+// into account those prefs it can verify whether certain UMA log upload is
+// allowed.
+class DataUseTracker {
+ public:
+  explicit DataUseTracker(PrefService* local_state);
+  ~DataUseTracker();
+
+  // Registers data use prefs using provided |registry|.
+  static void RegisterPrefs(PrefRegistrySimple* registry);
+
+  // Returns a callback to data use pref updating function attached to
+  // |data_use_tracker| weak pointer. Should be called on UI thread.
+  UpdateUsagePrefCallbackType GetDataUseForwardingCallback(
+      scoped_refptr<base::SequencedTaskRunner> ui_task_runner);
+
+  // Returns  whether a log with provided |log_bytes| can be uploaded according

[Alexei Svitkine (slow), 2016/03/31 22:18:03]

Remove extra space after Returns

[gayane -on leave until 09-2017, 2016/04/01 19:49:31]

Done.

+  // to data use ratio and UMA quota provided by finch experiment.

[Alexei Svitkine (slow), 2016/03/31 22:18:03]

Finch is an internal codename - don't use it in code.

[gayane -on leave until 09-2017, 2016/04/01 19:49:31]

Done.

+  bool CanUploadUMALog(int log_bytes);

[Alexei Svitkine (slow), 2016/03/31 22:18:03]

Nit: "ShouldUploadLogOnCellular"

[gayane -on leave until 09-2017, 2016/04/01 19:49:31]

Done.

+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(DataUseTrackerTest, CheckUpdateUsagePref);
+  FRIEND_TEST_ALL_PREFIXES(DataUseTrackerTest, CheckRemoveExpiredEntries);
+  FRIEND_TEST_ALL_PREFIXES(DataUseTrackerTest, CheckComputeTotalDataUse);
+  FRIEND_TEST_ALL_PREFIXES(DataUseTrackerTest, CheckCanUploadUMALog);
+
+  // Updates data usage prefs on UI thread according to what Prefservice
+  // expects.
+  void UpdateMetricsUsagePrefsOnUIThread(const std::string& service_name,
+                                         int message_size);
+
+  // Updates provided |pref_name| for a current date with the given message
+  // size.
+  void UpdateUsagePref(const std::string& pref_name, int message_size);
+
+  // Removes entries from the all data use  prefs.
+  void RemoveExpiredEntries();
+
+  // Removes entries from the given |pref_name| if they are more than 7 days
+  // old.
+  void RemoveExpiredEntriesForPref(const std::string& pref_name);
+
+  // Computes data usage according to all the entries in the given dictionary
+  // pref.
+  int ComputeTotalDataUse(std::string pref_name);
+
+  virtual bool GetUmaQuota(int* quota);
+  virtual bool GetUmaRatio(double* ratio);
+
+  // Returns the current date for measurement.
+  virtual base::Time GetCurrentMeasurementDate();
+
+  // Returns the current date as a string with a proper formatting.
+  virtual std::string GetCurrentMeasurementDateAsString();
+
+  PrefService* local_state_;
+
+  std::string date_for_testing_;
+  int uma_quota_for_testing_;
+  double uma_ratio_for_testing_;
+
+  base::ThreadChecker thread_checker_;
+
+  base::WeakPtrFactory<DataUseTracker> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(DataUseTracker);
+};
+
+}  // namespace metrics
+#endif  // COMPONENTS_METRICS_DATA_USE_TRACKER_H_