base: Use std::move() instead of Pass() for real movable types.

base/metrics/sparse_histogram.cc

Index: base/metrics/sparse_histogram.cc
diff --git a/base/metrics/sparse_histogram.cc b/base/metrics/sparse_histogram.cc
index 39c276d7877290a9a93123b728061cb06099c51b..7955c572811f2c685535f52cdb81f7c94b8955e2 100644
--- a/base/metrics/sparse_histogram.cc
+++ b/base/metrics/sparse_histogram.cc
@@ -4,6 +4,8 @@
 
 #include "base/metrics/sparse_histogram.h"
 
+#include <utility>
+
 #include "base/metrics/sample_map.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/pickle.h"
@@ -67,7 +69,7 @@ scoped_ptr<HistogramSamples> SparseHistogram::SnapshotSamples() const {
 
   base::AutoLock auto_lock(lock_);
   snapshot->Add(samples_);
-  return snapshot.Pass();
+  return std::move(snapshot);
 }
 
 void SparseHistogram::AddSamples(const HistogramSamples& samples) {