Rewrite std::string("") to std::string(), Linux edition.

chrome/test/perf/shutdown_test.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/environment.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/stringprintf.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/sys_info.h"
@@ skipping 96 matching lines @@
         clear_profile_ = false;
         // Clear template_user_data_ so we don't try to copy it over each time
         // through.
         set_template_user_data(base::FilePath());
       }
     }
 
     std::string times;
     for (int i = 0; i < numCycles; ++i)
       base::StringAppendF(&times, "%.2f,", timings[i].InMillisecondsF());
-    perf_test::PrintResultList(graph, "", trace, times, "ms", important);
+    perf_test::PrintResultList(
+        graph, std::string(), trace, times, "ms", important);
   }
 };
 
 TEST_F(ShutdownTest, DISABLED_SimpleWindowClose) {
   RunShutdownTest("shutdown", "simple-window-close",
                   true, /* important */ SIMPLE, ProxyLauncher::WINDOW_CLOSE);
 }
 
 TEST_F(ShutdownTest, SimpleUserQuit) {
   RunShutdownTest("shutdown", "simple-user-quit",
@@ skipping 32 matching lines @@
 #define MAYBE_TwentyTabsSessionEnding TwentyTabsSessionEnding
 #endif
 
 TEST_F(ShutdownTest, MAYBE_TwentyTabsSessionEnding) {
   RunShutdownTest("shutdown", "twentytabs-session-ending",
                   true, /* important */ TWENTY_TABS,
                   ProxyLauncher::SESSION_ENDING);
 }
 
 }  // namespace