Implement write methods for SparseHistogram

base/metrics/sparse_histogram.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_SPARSE_HISTOGRAM_H_
 #define BASE_METRICS_SPARSE_HISTOGRAM_H_
 
 #include <map>
 #include <string>
 
@@ skipping 72 matching lines @@
   explicit SparseHistogram(const std::string& name);
 
   friend BASE_EXPORT_PRIVATE HistogramBase* DeserializeHistogramInfo(
       PickleIterator* iter);
   static HistogramBase* DeserializeInfoImpl(PickleIterator* iter);
 
   virtual void GetParameters(DictionaryValue* params) const OVERRIDE;
   virtual void GetCountAndBucketData(Count* count,
                                      ListValue* buckets) const OVERRIDE;
 
+  // Helpers for emitting Ascii graphic.  Each method appends data to output.
+  void WriteAsciiImpl(bool graph_it,
+                      const std::string& newline,
+                      std::string* output) const;
+
+  // Write a common header message describing this histogram.
+  void WriteAsciiHeader(const Count total_count,
+                        std::string* output) const;
+
   // For constuctor calling.
   friend class SparseHistogramTest;
 
   // Protects access to |samples_|.
   mutable base::Lock lock_;
 
   SampleMap samples_;
 
   DISALLOW_COPY_AND_ASSIGN(SparseHistogram);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_SPARSE_HISTOGRAM_H_