Remove raw base::DictionaryValue::Set

services/preferences/tracked/tracked_preferences_migration.cc

Index: services/preferences/tracked/tracked_preferences_migration.cc
diff --git a/services/preferences/tracked/tracked_preferences_migration.cc b/services/preferences/tracked/tracked_preferences_migration.cc
index f2af336e350a08a60bcb010ffbcbf80b31267c29..61a0c80cf0b47c878cfc9db0778e63ecc5202404 100644
--- a/services/preferences/tracked/tracked_preferences_migration.cc
+++ b/services/preferences/tracked/tracked_preferences_migration.cc
@@ -9,6 +9,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/macros.h"
+#include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram.h"
 #include "base/values.h"
@@ -164,7 +165,8 @@ void MigratePrefsFromOldToNewStore(const std::set<std::string>& pref_names,
         // |new_store| having equivalently been successfully flushed to disk
         // (e.g., on crash or in cases where |new_store| is read-only following
         // a read error on startup).
-        new_store->Set(pref_name, value_in_old_store->DeepCopy());
+        new_store->Set(pref_name,
+                       base::MakeUnique<base::Value>(*value_in_old_store));
         migrated_value = true;
         *new_store_altered = true;
       }