Initialize StatisticsRecorder in Child Process to hold

base/metrics/statistics_recorder.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.
 
 // StatisticsRecorder handles all histograms in the system. It provides a
 // general place for histograms to register, and supports a global API for
 // accessing (i.e., dumping, or graphing) the data in all the histograms.
 
 #ifndef BASE_METRICS_STATISTICS_RECORDER_H_
 #define BASE_METRICS_STATISTICS_RECORDER_H_
 
 #include <list>
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
+#include "base/lazy_instance.h"
 
 namespace base {
 
 class CachedRanges;
 class Histogram;
 class Lock;
 
 class BASE_EXPORT StatisticsRecorder {
  public:
   typedef std::vector<Histogram*> Histograms;
 
-  StatisticsRecorder();
-
-  ~StatisticsRecorder();
+  // Initializes the StatisticsRecorder system.
+  static void Initialize();
 
   // Find out if histograms can now be registered into our list.
   static bool IsActive();
 
   // Register, or add a new histogram to the collection of statistics. If an
   // identically named histogram is already registered, then the argument
   // |histogram| will deleted.  The returned value is always the registered
   // histogram (either the argument, or the pre-existing registered histogram).
   static Histogram* RegisterOrDeleteDuplicate(Histogram* histogram);
 
@@ skipping 27 matching lines @@
   static bool dump_on_exit() { return dump_on_exit_; }
 
   static void set_dump_on_exit(bool enable) { dump_on_exit_ = enable; }
 
   // GetSnapshot copies some of the pointers to registered histograms into the
   // caller supplied vector (Histograms).  Only histograms with names matching
   // query are returned. The query must be a substring of histogram name for its
   // pointer to be copied.
   static void GetSnapshot(const std::string& query, Histograms* snapshot);
 
-
  private:
   // We keep all registered histograms in a map, from name to histogram.
   typedef std::map<std::string, Histogram*> HistogramMap;
 
   // We keep all |cached_ranges_| in a map, from checksum to a list of
   // |cached_ranges_|.  Checksum is calculated from the |ranges_| in
   // |cached_ranges_|.
   typedef std::map<uint32, std::list<CachedRanges*>*> RangesMap;
 
+  friend struct DefaultLazyInstanceTraits<StatisticsRecorder>;
+
+  // Allow tests to access our innards for testing purposes.
+  FRIEND_TEST_ALL_PREFIXES(HistogramTest, StartupShutdownTest);
+  FRIEND_TEST_ALL_PREFIXES(HistogramTest, RecordedStartupTest);
+  FRIEND_TEST_ALL_PREFIXES(HistogramTest, RangeTest);
+  FRIEND_TEST_ALL_PREFIXES(HistogramTest, CustomRangeTest);
+  FRIEND_TEST_ALL_PREFIXES(HistogramTest, CachedRangesTest);
+
+  StatisticsRecorder();
+
+  ~StatisticsRecorder();
+
   static HistogramMap* histograms_;
 
   static RangesMap* ranges_;
 
   // lock protects access to the above map.
   static base::Lock* lock_;
 
   // Dump all known histograms to log.
   static bool dump_on_exit_;
 
   DISALLOW_COPY_AND_ASSIGN(StatisticsRecorder);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_STATISTICS_RECORDER_H_