Add ownership-transfer to histogram management calls.

base/metrics/statistics_recorder.h

Index: base/metrics/statistics_recorder.h
diff --git a/base/metrics/statistics_recorder.h b/base/metrics/statistics_recorder.h
index 36b2f308af30bf8bc52d23a7ddfd9af69d22ccc7..12009f47a6543e75a14b1a1788fc077c80edd0dd 100644
--- a/base/metrics/statistics_recorder.h
+++ b/base/metrics/statistics_recorder.h
@@ -73,14 +73,15 @@ class BASE_EXPORT StatisticsRecorder {
   // identically named histogram is already registered, then the argument
   // |histogram| will deleted.  The returned value is always the registered
   // histogram (either the argument, or the pre-existing registered histogram).
-  static HistogramBase* RegisterOrDeleteDuplicate(HistogramBase* histogram);
+  static HistogramBase* RegisterOrDeleteDuplicate(
+      scoped_ptr<HistogramBase> histogram);
 
   // Register, or add a new BucketRanges. If an identically BucketRanges is
   // already registered, then the argument |ranges| will deleted. The returned
   // value is always the registered BucketRanges (either the argument, or the
   // pre-existing one).
   static const BucketRanges* RegisterOrDeleteDuplicateRanges(
-      const BucketRanges* ranges);
+      scoped_ptr<const BucketRanges> ranges);
 
   // Methods for appending histogram data to a string.  Only histograms which
   // have |query| as a substring are written to |output| (an empty string will