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

chrome/test/perf/dom_checker_uitest.cc

Index: chrome/test/perf/dom_checker_uitest.cc
diff --git a/chrome/test/perf/dom_checker_uitest.cc b/chrome/test/perf/dom_checker_uitest.cc
index f9662509033c6c76d7f7487a36be8c63f2b592f3..f22cce496190c30a3e0a6f2ad511c5640e71f57c 100644
--- a/chrome/test/perf/dom_checker_uitest.cc
+++ b/chrome/test/perf/dom_checker_uitest.cc
@@ -143,20 +143,24 @@ class DomCheckerTest : public UITest {
   }
 
   bool WaitUntilTestCompletes(TabProxy* tab) {
-    return WaitUntilJavaScriptCondition(tab, L"",
+    return WaitUntilJavaScriptCondition(
+        tab,
+        std::wstring(),
         L"window.domAutomationController.send(automation.IsDone());",
         TestTimeouts::large_test_timeout());
   }
 
   bool GetTestCount(TabProxy* tab, int* test_count) {
-    return tab->ExecuteAndExtractInt(L"",
+    return tab->ExecuteAndExtractInt(
+        std::wstring(),
         L"window.domAutomationController.send(automation.GetTestCount());",
         test_count);
   }
 
   bool GetTestsFailed(TabProxy* tab, ResultsSet* tests_failed) {
     std::wstring json_wide;
-    bool succeeded = tab->ExecuteAndExtractString(L"",
+    bool succeeded = tab->ExecuteAndExtractString(
+        std::wstring(),
         L"window.domAutomationController.send("
         L"    JSON.stringify(automation.GetFailures()));",
         &json_wide);