Add ownership-transfer to histogram management calls.

base/metrics/histogram.cc

Index: base/metrics/histogram.cc
diff --git a/base/metrics/histogram.cc b/base/metrics/histogram.cc
index ea4f8167fa28cc7098ce233cddbd7ed77fd23a77..40ae9c116fd18e1d353d5333631b762f778f7ef1 100644
--- a/base/metrics/histogram.cc
+++ b/base/metrics/histogram.cc
@@ -156,9 +156,10 @@ HistogramBase* Histogram::Factory::Build() {
   HistogramBase* histogram = StatisticsRecorder::FindHistogram(name_);
   if (!histogram) {
     // To avoid racy destruction at shutdown, the following will be leaked.
-    const BucketRanges* created_ranges = CreateRanges();
+    scoped_ptr<const BucketRanges> created_ranges(CreateRanges());
     const BucketRanges* registered_ranges =
-        StatisticsRecorder::RegisterOrDeleteDuplicateRanges(created_ranges);
+        StatisticsRecorder::RegisterOrDeleteDuplicateRanges(
+            std::move(created_ranges));
 
     // In most cases, the bucket-count, minimum, and maximum values are known
     // when the code is written and so are passed in explicitly. In other
@@ -177,7 +178,7 @@ HistogramBase* Histogram::Factory::Build() {
     // allocating from it fails, code below will allocate the histogram from
     // the process heap.
     PersistentMemoryAllocator::Reference histogram_ref = 0;
-    HistogramBase* tentative_histogram = nullptr;
+    scoped_ptr<HistogramBase> tentative_histogram;
     PersistentMemoryAllocator* allocator =
         GetPersistentHistogramMemoryAllocator();
     if (allocator) {
@@ -199,17 +200,18 @@ HistogramBase* Histogram::Factory::Build() {
       DCHECK(!histogram_ref);  // Should never have been set.
       DCHECK(!allocator);  // Shouldn't have failed.
       flags_ &= ~HistogramBase::kIsPersistent;
-      tentative_histogram = HeapAlloc(registered_ranges);
+      tentative_histogram.reset(HeapAlloc(registered_ranges));
     }
 
-    FillHistogram(tentative_histogram);
-    histogram =
-        StatisticsRecorder::RegisterOrDeleteDuplicate(tentative_histogram);
+    FillHistogram(tentative_histogram.get());
+    const void* allocated_histogram = tentative_histogram.get();
+    histogram = StatisticsRecorder::RegisterOrDeleteDuplicate(
+        std::move(tentative_histogram));
 
     // Persistent histograms need some follow-up processing.
     if (histogram_ref) {
       FinalizePersistentHistogram(histogram_ref,
-                                  histogram == tentative_histogram);
+                                  histogram == allocated_histogram);
     }
   }