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

chrome/browser/browsing_data/browsing_data_counter.h

Index: chrome/browser/browsing_data/browsing_data_counter.h
diff --git a/chrome/browser/browsing_data/browsing_data_counter.h b/chrome/browser/browsing_data/browsing_data_counter.h
index ba3afbd741fad06ec58a9a4c408f941766f2d176..d860e1f9d54906b0d04b860e28494d8ebd044470 100644
--- a/chrome/browser/browsing_data/browsing_data_counter.h
+++ b/chrome/browser/browsing_data/browsing_data_counter.h
@@ -16,7 +16,29 @@
 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();
@@ -38,13 +60,23 @@ class BrowsingDataCounter {
 
  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();