Improved iterator for persistent memory allocator.

components/metrics/file_metrics_provider.cc

Index: components/metrics/file_metrics_provider.cc
diff --git a/components/metrics/file_metrics_provider.cc b/components/metrics/file_metrics_provider.cc
index fcfb7acfb88a4bd772c4db3b9b1213a6a859a338..78fb90a1211c5f6b4e69330517e4197aef496c58 100644
--- a/components/metrics/file_metrics_provider.cc
+++ b/components/metrics/file_metrics_provider.cc
@@ -174,13 +174,12 @@ void FileMetricsProvider::RecordHistogramSnapshotsFromFile(
     base::HistogramSnapshotManager* snapshot_manager,
     FileInfo* file) {
   DCHECK(thread_checker_.CalledOnValidThread());
-  base::PersistentHistogramAllocator::Iterator histogram_iter;
-  file->allocator->CreateIterator(&histogram_iter);
+  base::PersistentHistogramAllocator::Iterator histogram_iter(
+      file->allocator.get());
 
   int histogram_count = 0;
   while (true) {
-    scoped_ptr<base::HistogramBase> histogram =
-        file->allocator->GetNextHistogram(&histogram_iter);
+    scoped_ptr<base::HistogramBase> histogram = histogram_iter.GetNext();
     if (!histogram)
       break;
     if (file->type == FILE_HISTOGRAMS_ATOMIC)