Tool found: pass by value when pass by reference is better in system wrapper unit test.

BUG=N/A

Review URL: https://webrtc-codereview.appspot.com/1186006

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3662 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/system_wrappers/source/data_log_unittest_disabled.cc b/system_wrappers/source/data_log_unittest_disabled.cc
index 583bde6..31d753e 100644
--- a/system_wrappers/source/data_log_unittest_disabled.cc
+++ b/system_wrappers/source/data_log_unittest_disabled.cc
@@ -18,7 +18,7 @@
 
 const char* kDataLogFileName = "table_1.txt";
 
-void PerformLogging(std::string table_name) {
+void PerformLogging(const std::string& table_name) {
   // Simulate normal DataTable logging behavior using this table name.
   ASSERT_EQ(0, DataLog::AddTable(table_name));
   ASSERT_EQ(0, DataLog::AddColumn(table_name, "test", 1));