Display histograms from subprocesses in chrome://histograms

base/metrics/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.
 
 // Histogram is an object that aggregates statistics, and can summarize them in
 // various forms, including ASCII graphical, HTML, and numerically (as a
 // vector of numbers corresponding to each of the aggregating buckets).
 
 // It supports calls to accumulate either time intervals (which are processed
 // as integral number of milliseconds), or arbitrary integral units.
@@ skipping 189 matching lines @@
   bool HasConstructionArguments(Sample expected_minimum,
                                 Sample expected_maximum,
                                 uint32_t expected_bucket_count) const override;
   void Add(Sample value) override;
   void AddCount(Sample value, int count) override;
   std::unique_ptr<HistogramSamples> SnapshotSamples() const override;
   std::unique_ptr<HistogramSamples> SnapshotDelta() override;
   std::unique_ptr<HistogramSamples> SnapshotFinalDelta() const override;
   void AddSamples(const HistogramSamples& samples) override;
   bool AddSamplesFromPickle(base::PickleIterator* iter) override;
-  void WriteHTMLGraph(std::string* output) const override;
-  void WriteAscii(std::string* output) const override;
+  void WriteHTMLGraph(const HistogramSamples* snapshot,
+                      std::string* output) const override;
+  void WriteAscii(const HistogramSamples* snapshot,
+                  std::string* output) const override;
 
  protected:
   // This class, defined entirely within the .cc file, contains all the
   // common logic for building a Histogram and can be overridden by more
   // specific types to alter details of how the creation is done. It is
   // defined as an embedded class (rather than an anonymous one) so it
   // can access the protected constructors.
   class Factory;
 
   // |ranges| should contain the underflow and overflow buckets. See top
@@ skipping 47 matching lines @@
   static HistogramBase* DeserializeInfoImpl(base::PickleIterator* iter);
 
   // Implementation of SnapshotSamples function.
   std::unique_ptr<SampleVector> SnapshotSampleVector() const;
 
   //----------------------------------------------------------------------------
   // Helpers for emitting Ascii graphic.  Each method appends data to output.
 
   void WriteAsciiImpl(bool graph_it,
                       const std::string& newline,
+                      const SampleVector* snapshot,
                       std::string* output) const;
 
   // Find out how large (graphically) the largest bucket will appear to be.
   double GetPeakBucketSize(const SampleVector& samples) const;
 
   // Write a common header message describing this histogram.
   void WriteAsciiHeader(const SampleVector& samples,
                         Count sample_count,
                         std::string* output) const;
 
@@ skipping 254 matching lines @@
   static HistogramBase* DeserializeInfoImpl(base::PickleIterator* iter);
 
   static bool ValidateCustomRanges(const std::vector<Sample>& custom_ranges);
 
   DISALLOW_COPY_AND_ASSIGN(CustomHistogram);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_H_