Replace use of logging::DEBUG_MODE with DCHECK_IS_ON().

components/sync/engine_impl/traffic_logger.cc

Index: components/sync/engine_impl/traffic_logger.cc
diff --git a/components/sync/engine_impl/traffic_logger.cc b/components/sync/engine_impl/traffic_logger.cc
index 1d88f4c53926b7cec1b3a3a0df4c69848bb238c2..24739dee354f2a879ba2c6f4e4e9f38d2c0f8c6e 100644
--- a/components/sync/engine_impl/traffic_logger.cc
+++ b/components/sync/engine_impl/traffic_logger.cc
@@ -21,7 +21,7 @@ void LogData(const T& data,
              std::unique_ptr<base::DictionaryValue> (
                  *to_dictionary_value)(const T&, bool),
              const std::string& description) {
-  if (::logging::DEBUG_MODE && VLOG_IS_ON(1)) {
+  if (DCHECK_IS_ON() && VLOG_IS_ON(1)) {
     std::unique_ptr<base::DictionaryValue> value =
         (*to_dictionary_value)(data, true /* include_specifics */);
     std::string message;