Display histograms from subprocesses in chrome://histograms

base/metrics/histogram.h

Index: base/metrics/histogram.h
diff --git a/base/metrics/histogram.h b/base/metrics/histogram.h
index d4d009c6ae01c1fa246c5e3a364969899a39aa4d..337ccd06c343933383d9b80e6c067c5ee900b36b 100644
--- a/base/metrics/histogram.h
+++ b/base/metrics/histogram.h
@@ -206,8 +206,10 @@ class BASE_EXPORT Histogram : public HistogramBase {
   std::unique_ptr<HistogramSamples> SnapshotDelta() 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
@@ -275,6 +277,7 @@ class BASE_EXPORT Histogram : public HistogramBase {
 
   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.