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

chrome/test/chromedriver/chrome/stub_chrome.cc

 // Copyright (c) 2013 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 "chrome/test/chromedriver/chrome/stub_chrome.h"
 #include "chrome/test/chromedriver/chrome/status.h"
 #include "chrome/test/chromedriver/chrome/web_view.h"
 
 StubChrome::StubChrome() {}
 
 StubChrome::~StubChrome() {}
 
 std::string StubChrome::GetVersion() {
-  return "";
+  return std::string();
 }
 
 int StubChrome::GetBuildNo() {
   return 9999;
 }
 
 Status StubChrome::GetWebViewIds(std::list<std::string>* web_view_ids) {
   return Status(kOk);
 }
 
@@ skipping 17 matching lines @@
     bool accept,
     const std::string& prompt_text) {
   return Status(kOk);
 }
 
 Status StubChrome::GetAutomationExtension(AutomationExtension** extension) {
   return Status(kOk);
 }
 
 std::string StubChrome::GetOperatingSystemName() {
-  return "";
+  return std::string();
 }
 
 Status StubChrome::Quit() {
   return Status(kOk);
 }