Cleanup: Pass std::string as const reference if possible

chrome/browser/nacl_host/test/gdb_debug_stub_browsertest.cc

Index: chrome/browser/nacl_host/test/gdb_debug_stub_browsertest.cc
diff --git a/chrome/browser/nacl_host/test/gdb_debug_stub_browsertest.cc b/chrome/browser/nacl_host/test/gdb_debug_stub_browsertest.cc
index b485361cc3bba529dd46e86a174ad640c4ec90b3..be034543278e4b13839a4544ce008632527c739f 100644
--- a/chrome/browser/nacl_host/test/gdb_debug_stub_browsertest.cc
+++ b/chrome/browser/nacl_host/test/gdb_debug_stub_browsertest.cc
@@ -23,7 +23,8 @@ class NaClGdbDebugStubTest : public PPAPINaClNewlibTest {
   void SetUpCommandLine(base::CommandLine* command_line) override;
 
   void StartTestScript(base::Process* test_process,
-                       std::string test_name, int debug_stub_port);
+                       const std::string& test_name,
+                       int debug_stub_port);
   void RunDebugStubTest(const std::string& nacl_module,
                         const std::string& test_name);
 };
@@ -34,7 +35,7 @@ void NaClGdbDebugStubTest::SetUpCommandLine(base::CommandLine* command_line) {
 }
 
 void NaClGdbDebugStubTest::StartTestScript(base::Process* test_process,
-                                           std::string test_name,
+                                           const std::string& test_name,
                                            int debug_stub_port) {
   // We call python script to reuse GDB RSP protocol implementation.
   base::CommandLine cmd(base::FilePath(FILE_PATH_LITERAL("python")));