Let MetricsService know about some Android Activities

base/metrics/histogram_snapshot_manager.h

 // Copyright (c) 2012 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 BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_
 #define BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 12 matching lines @@
 // corruption, this class also validates as much rendundancy as it can before
 // calling for the marginal change (a.k.a., delta) in a histogram to be
 // recorded.
 class BASE_EXPORT HistogramSnapshotManager {
  public:
   explicit HistogramSnapshotManager(HistogramFlattener* histogram_flattener);
   virtual ~HistogramSnapshotManager();
 
   // Snapshot all histograms, and ask |histogram_flattener_| to record the
   // delta. The arguments allow selecting only a subset of histograms for
   // recording, or to set a flag in each recorded histogram.

[Alexei Svitkine (slow), 2014/01/22 21:14:19]

Please expand comment to explain |flag_filter_to_record|. Specifically, if you
pass multiple flags in that param, does "any" of them have to be set or do they
"all" have to be set. (In your implementation, it looks like "all").

Also, please add unit tests for this.

[Kibeom Kim (inactive), 2014/01/24 19:45:09]

Done.

-  void PrepareDeltas(HistogramBase::Flags flags_to_set, bool record_only_uma);
+  // If everything need to be recorded, set |flag_filter_to_record| to
+  // Histogram::kNoFlags .
+  void PrepareDeltas(HistogramBase::Flags flags_to_set,
+                     HistogramBase::Flags flag_filter_to_record);
 
  private:
   // Snapshot this histogram, and record the delta.
   void PrepareDelta(const HistogramBase& histogram);
 
   // Try to detect and fix count inconsistency of logged samples.
   void InspectLoggedSamplesInconsistency(
       const HistogramSamples& new_snapshot,
       HistogramSamples* logged_samples);
 
   // For histograms, track what we've already recorded (as a sample for
   // each histogram) so that we can record only the delta with the next log.
   std::map<std::string, HistogramSamples*> logged_samples_;
 
   // List of histograms found to be corrupt, and their problems.
   std::map<std::string, int> inconsistencies_;
 
   // |histogram_flattener_| handles the logistics of recording the histogram
   // deltas.
   HistogramFlattener* histogram_flattener_;  // Weak.
 
   DISALLOW_COPY_AND_ASSIGN(HistogramSnapshotManager);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_SNAPSHOT_MANAGER_H_