Add comments to HistogramFlatterner interface and rename a function

base/metrics/histogram_flattener.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_FLATTENER_H_
 #define BASE_METRICS_HISTOGRAM_FLATTENER_H_
 
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
 
 namespace base {
 
 // HistogramFlattener is an interface for the logistics of gathering up
 // available histograms for recording. The implementors handle the exact lower
 // level recording mechanism, or error report mechanism.
 class BASE_EXPORT HistogramFlattener {
  public:
   virtual void RecordDelta(const base::Histogram& histogram,
                            const base::Histogram::SampleSet& snapshot) = 0;
 
-  // Record various errors found during attempts to record histograms.
-  virtual void InconsistencyDetected(int problem) = 0;
-  virtual void UniqueInconsistencyDetected(int problem) = 0;
-  virtual void SnapshotProblemResolved(int amount) = 0;
+  // Will be called each time when a type of Inconsistenies is seen on a

[jar (doing other things), 2012/08/20 02:41:49]

nit: remove either "each time" or "when".

Clarify the passive voice "Will be" by clarifying who/when the call is made. 
Suggest adding the postfix to your sentence:
"... during inspections done internally to the RecordDelta() method."

+  // histogram.
+  virtual void InconsistencyDetected(Histogram::Inconsistencies problem) = 0;
+
+  // Will be called when a type of Inconsistenies is seen for the first time
+  // on a histogram.

[jar (doing other things), 2012/08/20 02:41:49]

nit: clarify who/when this is called, such as was suggested above"

+  virtual void UniqueInconsistencyDetected(
+      Histogram::Inconsistencies problem) = 0;
+
+  // Will be called when the logged samples count of a histogram has
+  // inconsistency. |amount| is the difference.

[jar (doing other things), 2012/08/20 02:41:49]

nit: Clarify this line, possibly by replacing the whole comment with:

Will be called by RecordDelta() when the logged sample count for the entire
histogram differs from the sum of the sample count in all the buckets.  The
argument |amount| is the non-zero discrepancy. 

+  virtual void InconsistencyDetectedInLoggedCount(int amount) = 0;
 
  protected:
   HistogramFlattener() {}
   virtual ~HistogramFlattener() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(HistogramFlattener);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_FLATTENER_H_