Connect SparseHistogram with the rest of stats system

base/metrics/histogram_base.h

Index: base/metrics/histogram_base.h
diff --git a/base/metrics/histogram_base.h b/base/metrics/histogram_base.h
index 729670cf98699e9af4a3215b6494cc62cdd515d0..e4cff7e7947ad3e404045452516c8f527bd259dd 100644
--- a/base/metrics/histogram_base.h
+++ b/base/metrics/histogram_base.h
@@ -48,6 +48,17 @@ BASE_EXPORT void DeserializeHistogramAndAddSamples(PickleIterator* iter);
 
 ////////////////////////////////////////////////////////////////////////////////
 
+// Histogram data inconsistency types.
+enum BASE_EXPORT HistogramInconsistency {
+  NO_INCONSISTENCIES = 0x0,
+  RANGE_CHECKSUM_ERROR = 0x1,
+  BUCKET_ORDER_ERROR = 0x2,
+  COUNT_HIGH_ERROR = 0x4,
+  COUNT_LOW_ERROR = 0x8,
+
+  NEVER_EXCEEDED_VALUE = 0x10
+};
+
 class BASE_EXPORT HistogramBase {
  public:
   typedef int Sample;  // Used for samples.
@@ -103,6 +114,10 @@ class BASE_EXPORT HistogramBase {
   // does not serialize the samples.
   bool SerializeInfo(Pickle* pickle) const;
 
+  // Try to find out data corruption from histogram and the samples.
+  // The returned value is a combination of HistogramInconsistency enum.
+  virtual int32 FindCorruption(const HistogramSamples& samples) const;

[jar (doing other things), 2013/02/27 23:51:38]

nit: I see why you made it an integral return type, rather than an enum, so as
to avoid the cast on the OR of enumeators.

Why int32?  Why not the more common int, or if you really care about the size
(relative to the flags you pass), then int16?

[kaiwang, 2013/02/28 04:58:05]

Done.

+
   // Snapshot the current complete set of sample data.
   // Override with atomic/locked snapshot if needed.
   virtual scoped_ptr<HistogramSamples> SnapshotSamples() const = 0;