Add ownership-transfer to histogram management calls.

base/metrics/histogram_persistence.h

 // Copyright (c) 2015 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 BASE_METRICS_HISTOGRAM_PERSISTENCE_H_
 #define BASE_METRICS_HISTOGRAM_PERSISTENCE_H_
 
 #include "base/base_export.h"
 #include "base/feature_list.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 31 matching lines @@
 // Recreate a Histogram from data held in persistent memory. Though this
 // object will be local to the current process, the sample data will be
 // shared with all other threads referencing it. This method takes a |ref|
 // to the top- level histogram data and the |allocator| on which it is found.
 // This method will return nullptr if any problem is detected with the data.
 // The |allocator| may or may not be the same as the PersistentMemoryAllocator
 // set for general use so that this method can be used to extract Histograms
 // from persistent memory segments other than the default place that this
 // process is creating its own histograms. The caller must take ownership of
 // the returned object and destroy it when no longer needed.
-BASE_EXPORT HistogramBase* GetPersistentHistogram(
+BASE_EXPORT scoped_ptr<HistogramBase> GetPersistentHistogram(
     PersistentMemoryAllocator* allocator,
     int32_t ref);
 
 // Get the next histogram in persistent data based on iterator. The caller
 // must take ownership of the returned object and destroy it when no longer
 // needed.
-BASE_EXPORT HistogramBase* GetNextPersistentHistogram(
+BASE_EXPORT scoped_ptr<HistogramBase> GetNextPersistentHistogram(
     PersistentMemoryAllocator* allocator,
     PersistentMemoryAllocator::Iterator* iter);
 
 // Finalize the creation of the histogram, making it available to other
 // processes if it is the registered instance.
 void FinalizePersistentHistogram(PersistentMemoryAllocator::Reference ref,
                                  bool register);
 
 // Allocate a new persistent histogram. This does *not* make the object
 // iterable in the allocator; call MakeIterable(ref) directly if that is
 // desired.
-BASE_EXPORT HistogramBase* AllocatePersistentHistogram(
+BASE_EXPORT scoped_ptr<HistogramBase> AllocatePersistentHistogram(
     PersistentMemoryAllocator* allocator,
     HistogramType histogram_type,
     const std::string& name,
     int minimum,
     int maximum,
     const BucketRanges* bucket_ranges,
     int32_t flags,
     PersistentMemoryAllocator::Reference* ref_ptr);
 
 // Import new histograms from attached PersistentMemoryAllocator. It's
 // possible for other processes to create histograms in the attached memory
 // segment; this adds those to the internal list of known histograms to
 // avoid creating duplicates that would have to merged during reporting.
 // Every call to this method resumes from the last entry it saw so it costs
 // nothing if nothing new has been added.
 void ImportPersistentHistograms();
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_PERSISTENCE_H_