Polish the result communication and display of the browsing data counters.

chrome/browser/browsing_data/browsing_data_counter.h

 // Copyright (c) 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 CHROME_BROWSER_BROWSING_DATA_BROWSING_DATA_COUNTER_H_
 #define CHROME_BROWSER_BROWSING_DATA_BROWSING_DATA_COUNTER_H_
 
 #include <stdint.h>
 #include <string>
 
 #include "base/callback.h"
 #include "base/prefs/pref_member.h"
 #include "chrome/browser/browsing_data/browsing_data_remover.h"
 #include "chrome/browser/profiles/profile.h"
 
 class BrowsingDataCounter {
  public:
   typedef uint64_t ResultInt;
-  typedef base::Callback<void(bool, ResultInt)> Callback;
+
+  class Result {
+   public:
+    Result(const BrowsingDataCounter* source, bool finished, ResultInt value);

[Bernhard Bauer, 2015/11/02 16:15:27]

Do you want someone to construct object of this class? If not, make the
constructor public.

[msramek, 2015/11/02 20:54:05]

That is what I also did originally, I just didn't like to have to make
FinishedResult and PendingResult its friends.

Anyway, according to your other comment, when we make finished virtual and move
value to FinishedResult, there is no difference between Result and
PendingResult. So I removed PendingResult and the constructor can stay public
here.

+    ~Result();
+
+    const BrowsingDataCounter* source() const { return source_; }
+    bool finished() const { return finished_; }
+    const ResultInt& value() const { return value_; }
+
+   private:
+    const BrowsingDataCounter* source_;
+    bool finished_;

[Bernhard Bauer, 2015/11/02 16:15:27]

Hm... seeing as we have this class structure now, and it looks like |finished_|
and |value_| are going to be mutually exclusive, would it make sense to move
|value_| to FinishedResult and make both Value() and Finished() virtual?

[msramek, 2015/11/02 20:54:06]

Yes! Done.

+    ResultInt value_;
+  };
+
+  class FinishedResult : public Result {
+   public:
+    FinishedResult(const BrowsingDataCounter* source, ResultInt value);
+    ~FinishedResult();
+  };
+
+  typedef base::Callback<void(scoped_ptr<Result>)> Callback;
 
   BrowsingDataCounter();
   virtual ~BrowsingDataCounter();
 
   // Should be called once to initialize this class.
   void Init(Profile* profile,
             const Callback& callback);
 
   // Name of the preference associated with this counter.
   virtual const std::string& GetPrefName() const = 0;
 
   // The profile associated with this counter.
   Profile* GetProfile() 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 the |result|.
-  void ReportResult(ResultInt result);
+  // 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(scoped_ptr<Result> result);
 
   // Calculates the beginning of the counting period as |period_| before now.
   base::Time GetPeriodStart();
 
  private:
+  class PendingResult : public Result {
+   public:
+    explicit PendingResult(const BrowsingDataCounter* source);
+    ~PendingResult();
+  };
+
   // Called after the class is initialized by calling |Init|.
   virtual void OnInitialized();
 
   // Count the data.
   virtual void Count() = 0;
 
   // The profile for which we will count the data volume.
   Profile* profile_;
 
   // 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;
 };
 
 #endif  // CHROME_BROWSER_BROWSING_DATA_BROWSING_DATA_COUNTER_H_