Use ThreadChecker in HistogramDeltaSerialization class.

base/metrics/histogram_delta_serialization.h

 // 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_SERIALIZATION_H_
 #define BASE_METRICS_HISTOGRAM_DELTA_SERIALIZATION_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"
+#include "base/threading/thread_checker.h"
 
 namespace base {
 
 class HistogramBase;
 
 // Serializes and restores histograms deltas.
 class BASE_EXPORT HistogramDeltaSerialization : public HistogramFlattener {
  public:
   // |caller_name| is string used in histograms for counting inconsistencies.
   explicit HistogramDeltaSerialization(const std::string& caller_name);
@@ skipping 12 matching lines @@
 
  private:
   // HistogramFlattener implementation.
   void RecordDelta(const HistogramBase& histogram,
                    const HistogramSamples& snapshot) override;
   void InconsistencyDetected(HistogramBase::Inconsistency problem) override;
   void UniqueInconsistencyDetected(
       HistogramBase::Inconsistency problem) override;
   void InconsistencyDetectedInLoggedCount(int amount) override;
 
+  ThreadChecker thread_checker_;
+
   // Calculates deltas in histogram counters.
   HistogramSnapshotManager histogram_snapshot_manager_;
 
   // Output buffer for serialized deltas.
   std::vector<std::string>* serialized_deltas_;
 
   // Histograms to count inconsistencies in snapshots.
   HistogramBase* inconsistencies_histogram_;
   HistogramBase* inconsistencies_unique_histogram_;
   HistogramBase* inconsistent_snapshot_histogram_;
 
   DISALLOW_COPY_AND_ASSIGN(HistogramDeltaSerialization);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_DELTA_SERIALIZATION_H_