Make browsing_data component a layered component

components/browsing_data/counters/browsing_data_counter.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_BROWSING_DATA_COUNTERS_BROWSING_DATA_COUNTER_H_
-#define COMPONENTS_BROWSING_DATA_COUNTERS_BROWSING_DATA_COUNTER_H_
-
-#include <stdint.h>
-#include <string>
-
-#include "base/callback.h"
-#include "base/macros.h"
-#include "components/prefs/pref_member.h"
-
-class PrefService;
-
-namespace browsing_data {
-
-class BrowsingDataCounter {
- public:
-  typedef int64_t ResultInt;
-
-  // Base class of results returned by BrowsingDataCounter. When the computation
-  // has started, an instance is returned to represent a pending result.
-  class Result {
-   public:
-    explicit Result(const BrowsingDataCounter* source);
-    virtual ~Result();
-
-    const BrowsingDataCounter* source() const { return source_; }
-    virtual bool Finished() const;
-
-   private:
-    const BrowsingDataCounter* source_;
-
-    DISALLOW_COPY_AND_ASSIGN(Result);
-  };
-
-  // A subclass of Result returned when the computation has finished. The result
-  // value can be retrieved by calling |Value()|. Some BrowsingDataCounter
-  // subclasses might use a subclass of FinishedResult to provide more complex
-  // results.
-  class FinishedResult : public Result {
-   public:
-    FinishedResult(const BrowsingDataCounter* source, ResultInt value);
-    ~FinishedResult() override;
-
-    // Result:
-    bool Finished() const override;
-
-    ResultInt Value() const;
-
-   private:
-    ResultInt value_;
-
-    DISALLOW_COPY_AND_ASSIGN(FinishedResult);
-  };
-
-  typedef base::Callback<void(std::unique_ptr<Result>)> Callback;
-
-  BrowsingDataCounter(const std::string& pref_name);
-  virtual ~BrowsingDataCounter();
-
-  // Should be called once to initialize this class.
-  void Init(PrefService* pref_service, const Callback& callback);
-
-  // Name of the preference associated with this counter.
-  const std::string& GetPrefName() const;
-
-  // PrefService that manages the preferences for the user profile
-  // associated with this counter.
-  PrefService* GetPrefs() const;
-
-  // Restarts the counter. Will be called automatically if the counting needs
-  // to be restarted, e.g. when the deletion preference changes state or when
-  // we are notified of data changes.
-  void Restart();
-
- protected:
-  // Should be called from |Count| by any overriding class to indicate that
-  // counting is finished and report |value| as the result.
-  void ReportResult(ResultInt value);
-
-  // A convenience overload of the previous method that allows subclasses to
-  // provide a custom |result|.
-  void ReportResult(std::unique_ptr<Result> result);
-
-  // Calculates the beginning of the counting period as |period_| before now.
-  base::Time GetPeriodStart();
-
- private:
-  // Called after the class is initialized by calling |Init|.
-  virtual void OnInitialized();
-
-  // Count the data.
-  virtual void Count() = 0;
-
-  // Name of the preference associated with this counter.
-  const std::string pref_name_;
-
-  // Pointer to the PrefService that manages the preferences for the user
-  // profile associated with this counter.
-  PrefService* pref_service_;
-
-  // The callback that will be called when the UI should be updated with a new
-  // counter value.
-  Callback callback_;
-
-  // The boolean preference indicating whether this data type is to be deleted.
-  // If false, we will not count it.
-  BooleanPrefMember pref_;
-
-  // The integer preference describing the time period for which this data type
-  // is to be deleted.
-  IntegerPrefMember period_;
-
-  // Whether this class was properly initialized by calling |Init|.
-  bool initialized_ = false;
-};
-
-}  // namespace browsing_data
-
-#endif  // COMPONENTS_BROWSING_DATA_COUNTERS_BROWSING_DATA_COUNTER_H_