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

net/cookies/cookie_store_test_helpers.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 "net/cookies/cookie_store_test_helpers.h"
 
 #include "base/bind.h"
 #include "base/message_loop.h"
 
 namespace net {
@@ skipping 72 matching lines @@
     const std::string& cookie_line,
     const CookieOptions& options) {
   ADD_FAILURE();
   return false;
 }
 
 std::string DelayedCookieMonster::GetCookiesWithOptions(
     const GURL& url,
     const CookieOptions& options) {
   ADD_FAILURE();
-  return "";
+  return std::string();
 }
 
 void DelayedCookieMonster::DeleteCookie(const GURL& url,
                                         const std::string& cookie_name) {
   ADD_FAILURE();
 }
 
 void DelayedCookieMonster::DeleteCookieAsync(const GURL& url,
                                              const std::string& cookie_name,
                                              const base::Closure& callback) {
   ADD_FAILURE();
 }
 
 void DelayedCookieMonster::DeleteAllCreatedBetweenAsync(
     const base::Time& delete_begin,
     const base::Time& delete_end,
     const DeleteCallback& callback) {
   ADD_FAILURE();
 }
 
 void DelayedCookieMonster::DeleteSessionCookiesAsync(const DeleteCallback&) {
   ADD_FAILURE();
 }
 
 CookieMonster* DelayedCookieMonster::GetCookieMonster() {
   return cookie_monster_;
 }
 
 }  // namespace net