Move StatisticsRecorder out of histogram.cc/h for further refactoring.

base/metrics/histogram_snapshot_manager.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/histogram_snapshot_manager.h"
 
+#include "base/metrics/statistics_recorder.h"
+
 using base::Histogram;
 using base::StatisticsRecorder;
 
 namespace base {
 
 HistogramSnapshotManager::HistogramSnapshotManager(
     HistogramFlattener* histogram_flattener)
     : histogram_flattener_(histogram_flattener) {
   DCHECK(histogram_flattener_);
 }
@@ skipping 78 matching lines @@
   }
 
   // Snapshot now contains only a delta to what we've already_logged.
   if (snapshot.redundant_count() > 0) {
     histogram_flattener_->RecordDelta(histogram, snapshot);
     // Add new data into our running total.
     already_logged->Add(snapshot);
   }
 }
 }  // namespace base