histogram synchronizer code between renderer and browser for UMA and about_histogram

chrome/renderer/renderer_histogram_snapshots.h

 // Copyright (c) 2006-2008 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 CHROME_RENDERER_HISTOGRAM_SNAPSHOTS_H_
 #define CHROME_RENDERER_HISTOGRAM_SNAPSHOTS_H_
 
 #include <list>
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/histogram.h"
 #include "base/process.h"
 #include "base/scoped_ptr.h"
 #include "base/task.h"
 
 class RendererHistogramSnapshots {
  public:
   RendererHistogramSnapshots();
 
   ~RendererHistogramSnapshots() {}
 
   // Send the histogram data.
-  void SendHistograms();
+  void SendHistograms(int sequence_number);
 
   // Maintain a map of histogram names to the sample stats we've sent.
   typedef std::map<std::string, Histogram::SampleSet> LoggedSampleMap;
   typedef std::vector<std::string> HistogramPickledList;
 
  private:
   // Extract snapshot data and then send it off the the Browser process.
   // Send only a delta to what we have already sent.
-  void UploadAllHistrograms();
+  void UploadAllHistrograms(int sequence_number);
   void UploadHistrogram(const Histogram& histogram,
                         HistogramPickledList* histograms);
   void UploadHistogramDelta(const Histogram& histogram,
                             const Histogram::SampleSet& snapshot,
                             HistogramPickledList* histograms);
 
   ScopedRunnableMethodFactory<RendererHistogramSnapshots>
       renderer_histogram_snapshots_factory_;
 
   // For histograms, record what we've already logged (as a sample for each
   // histogram) so that we can send only the delta with the next log.
   LoggedSampleMap logged_samples_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererHistogramSnapshots);
 };
 
 #endif  // CHROME_RENDERER_HISTOGRAM_SNAPSHOTS_H_