Add ownership-transfer to histogram management calls.

base/metrics/histogram_persistence.h

Index: base/metrics/histogram_persistence.h
diff --git a/base/metrics/histogram_persistence.h b/base/metrics/histogram_persistence.h
index 95f48784c9859a3a0003092ca37f258ee047a1b9..bf572947aba43b55ff45d742890269304be9c571 100644
--- a/base/metrics/histogram_persistence.h
+++ b/base/metrics/histogram_persistence.h
@@ -49,14 +49,14 @@ ReleasePersistentHistogramMemoryAllocatorForTesting();
 // 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);
 
@@ -68,7 +68,7 @@ void FinalizePersistentHistogram(PersistentMemoryAllocator::Reference ref,
 // 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,