Consolidate serialization code in base::HistogramDeltasSerializer.

base/metrics/histogram_delta_serializer.h

Index: base/metrics/histogram_delta_serializer.h
diff --git a/base/metrics/histogram_delta_serializer.h b/base/metrics/histogram_delta_serializer.h
new file mode 100644
index 0000000000000000000000000000000000000000..092c3b5461057695e7e4dc273a1e8f20bfbb92aa
--- /dev/null
+++ b/base/metrics/histogram_delta_serializer.h
@@ -0,0 +1,62 @@
+// Copyright 2013 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_DELTA_SERIALIZER_BASE_H_
+#define BASE_METRICS_HISTOGRAM_DELTA_SERIALIZER_BASE_H_
+
+#include <string>
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/metrics/histogram_flattener.h"
+#include "base/metrics/histogram_snapshot_manager.h"
+
+namespace base {
+
+class HistogramBase;
+
+// Serializes and restores histograms deltas.
+class BASE_EXPORT HistogramDeltasSerializer : public HistogramFlattener {
+ public:
+  // |caller_name| is string used in histograms for counting inconsistencies.
+  explicit HistogramDeltasSerializer(const std::string& caller_name);
+  virtual ~HistogramDeltasSerializer();
+
+  // Returns serialized deltas in histograms counters happened after previous
+  // call.

[Ilya Sherman, 2013/10/17 22:41:47]

nit: I'd suggest a wording more like: "Computes deltas in histogram bucket
counts relative to the previous call to this method.  Returns the deltas in
serialized form."  Feel free to improve my wording further, of course.

[Vitaly Buka (NO REVIEWS), 2013/10/18 05:33:35]

Done.

+  const std::vector<std::string>& GetNewDeltas();
+
+  // Deserialize deltas and add samples to corresponding histograms, creating
+  // them if necessary. Silently ignores errors in |deltas|.
+  static void DeserializeAndAddSamples(const std::vector<std::string>& deltas);
+
+ private:
+  // HistogramFlattener implementation.
+  virtual void RecordDelta(const HistogramBase& histogram,
+                           const HistogramSamples& snapshot) OVERRIDE;
+  virtual void InconsistencyDetected(
+      HistogramBase::Inconsistency problem) OVERRIDE;
+  virtual void UniqueInconsistencyDetected(
+      HistogramBase::Inconsistency problem) OVERRIDE;
+  virtual void InconsistencyDetectedInLoggedCount(int amount) OVERRIDE;
+
+  // Calculates deltas in histogram counters.
+  HistogramSnapshotManager histogram_snapshot_manager_;
+
+  // Output buffet for serialized deltas.

[Ilya Sherman, 2013/10/17 22:41:47]

nit: "buffet" -> "buffer"

[Vitaly Buka (NO REVIEWS), 2013/10/18 05:33:35]

Done.

+  std::vector<std::string> serialized_deltas_;
+
+  // Histograms to count inconsistencies in snapshots.
+  HistogramBase* inconsistencies_histogram_;
+  HistogramBase* inconsistencies_unique_histogram_;
+  HistogramBase* inconsistent_stapshot_histogram_;

[Ilya Sherman, 2013/10/17 22:41:47]

nit: "stapshot" -> "snapshot"

[Vitaly Buka (NO REVIEWS), 2013/10/18 05:33:35]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(HistogramDeltasSerializer);
+};
+
+}  // namespace base
+
+#endif  // BASE_METRICS_HISTOGRAM_DELTA_SERIALIZER_BASE_H_