Break global impact of PersistentHistogramAllocator into a separate class.

base/metrics/statistics_recorder.cc

 // 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.
 
 #include "base/metrics/statistics_recorder.h"
 
 #include "base/at_exit.h"
 #include "base/debug/leak_annotations.h"
 #include "base/json/string_escape.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/metrics_hashes.h"
+#include "base/metrics/persistent_histogram_allocator.h"
 #include "base/stl_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/lock.h"
 #include "base/values.h"
 
 namespace {
 
 // Initialize histogram statistics gathering system.
 base::LazyInstance<base::StatisticsRecorder>::Leaky g_statistics_recorder_ =
     LAZY_INSTANCE_INITIALIZER;
@@ skipping 257 matching lines @@
 }
 
 // static
 HistogramBase* StatisticsRecorder::FindHistogram(base::StringPiece name) {
   if (lock_ == NULL)
     return NULL;
   base::AutoLock auto_lock(*lock_);
   if (histograms_ == NULL)
     return NULL;
 
+  // Import histograms from known persistent storage. Histograms could have
+  // been added by other processes and they must be fetched and recognized
+  // locally. If the persistent memory segment is not shared between processes,
+  // this call does nothing.
+  GlobalHistogramAllocator* allocator = GlobalHistogramAllocator::Get();
+  if (allocator)
+    allocator->ImportHistogramsToStatisticsRecorder();
+
   HistogramMap::iterator it = histograms_->find(HashMetricName(name));
   if (histograms_->end() == it)
     return NULL;
   DCHECK_EQ(name, it->second->histogram_name()) << "hash collision";
   return it->second;
 }
 
 // static
 StatisticsRecorder::HistogramIterator StatisticsRecorder::begin(
     bool include_persistent) {
@@ skipping 156 matching lines @@
 // static
 StatisticsRecorder::HistogramMap* StatisticsRecorder::histograms_ = NULL;
 // static
 StatisticsRecorder::CallbackMap* StatisticsRecorder::callbacks_ = NULL;
 // static
 StatisticsRecorder::RangesMap* StatisticsRecorder::ranges_ = NULL;
 // static
 base::Lock* StatisticsRecorder::lock_ = NULL;
 
 }  // namespace base