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

chrome/browser/policy/cloud/mock_cloud_policy_client.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 "chrome/browser/policy/cloud/mock_cloud_policy_client.h"
 #include "chrome/browser/policy/cloud/proto/device_management_backend.pb.h"
 
 namespace em = enterprise_management;
 
 namespace policy {
 
 MockCloudPolicyClient::MockCloudPolicyClient()
-    : CloudPolicyClient("", "", USER_AFFILIATION_NONE, NULL, NULL) {}
+    : CloudPolicyClient(std::string(),
+                        std::string(),
+                        USER_AFFILIATION_NONE,
+                        NULL,
+                        NULL) {}
 
 MockCloudPolicyClient::~MockCloudPolicyClient() {}
 
 void MockCloudPolicyClient::SetDMToken(const std::string& token) {
   dm_token_ = token;
 }
 
 void MockCloudPolicyClient::SetPolicy(const PolicyNamespaceKey& policy_ns_key,
                                       const em::PolicyFetchResponse& policy) {
   em::PolicyFetchResponse*& response = responses_[policy_ns_key];
   delete response;
   response = new enterprise_management::PolicyFetchResponse(policy);
 }
 
 void MockCloudPolicyClient::SetStatus(DeviceManagementStatus status) {
   status_ = status;
 }
 
 MockCloudPolicyClientObserver::MockCloudPolicyClientObserver() {}
 
 MockCloudPolicyClientObserver::~MockCloudPolicyClientObserver() {}
 
 }  // namespace policy