Use acquire/relase for delayed persistent allocations.

base/metrics/persistent_histogram_allocator.cc

 // Copyright 2016 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/persistent_histogram_allocator.h"
 
 #include <memory>
 
 #include "base/atomicops.h"
 #include "base/files/file_path.h"
@@ skipping 592 matching lines @@
     RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_RANGES_ARRAY);
     NOTREACHED();
     return nullptr;
   }
   const BucketRanges* ranges =
       StatisticsRecorder::RegisterOrDeleteDuplicateRanges(
           created_ranges.release());
 
   size_t counts_bytes = CalculateRequiredCountsBytes(histogram_bucket_count);
   PersistentMemoryAllocator::Reference counts_ref =
-      subtle::NoBarrier_Load(&histogram_data_ptr->counts_ref);
+      subtle::Acquire_Load(&histogram_data_ptr->counts_ref);
   if (counts_bytes == 0 ||
       (counts_ref != 0 &&
        memory_allocator_->GetAllocSize(counts_ref) < counts_bytes)) {
     RecordCreateHistogramResult(CREATE_HISTOGRAM_INVALID_COUNTS_ARRAY);
     NOTREACHED();
     return nullptr;
   }
 
   // The "counts" data (including both samples and logged samples) is a delayed
   // persistent allocation meaning that though its size and storage for a
@@ skipping 340 matching lines @@
   while (true) {
     std::unique_ptr<HistogramBase> histogram =
         import_iterator_.GetNextWithIgnore(record_to_ignore);
     if (!histogram)
       break;
     StatisticsRecorder::RegisterOrDeleteDuplicate(histogram.release());
   }
 }
 
 }  // namespace base