Convert JsonWriter::Write to taking a const ref for the in-param

sync/engine/traffic_logger.cc

Index: sync/engine/traffic_logger.cc
diff --git a/sync/engine/traffic_logger.cc b/sync/engine/traffic_logger.cc
index bc285bd6616cf66ecc9a6f6b0f6f869d29438e53..1e9a6bc75fe6e12aed4d8c3621c877be936a07ae 100644
--- a/sync/engine/traffic_logger.cc
+++ b/sync/engine/traffic_logger.cc
@@ -25,9 +25,8 @@ void LogData(const T& data,
     scoped_ptr<base::DictionaryValue> value =
         (*to_dictionary_value)(data, true /* include_specifics */);
     std::string message;
-    base::JSONWriter::WriteWithOptions(value.get(),
-        base::JSONWriter::OPTIONS_PRETTY_PRINT,
-        &message);
+    base::JSONWriter::WriteWithOptions(
+        *value, base::JSONWriter::OPTIONS_PRETTY_PRINT, &message);
     DVLOG(1) << "\n" << description << "\n" << message << "\n";
   }
 }