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

net/udp/udp_socket_unittest.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/udp/udp_client_socket.h"
 #include "net/udp/udp_server_socket.h"
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/metrics/histogram.h"
@@ skipping 20 matching lines @@
 
   // Blocks until data is read from the socket.
   std::string RecvFromSocket(UDPServerSocket* socket) {
     TestCompletionCallback callback;
 
     int rv = socket->RecvFrom(buffer_, kMaxRead, &recv_from_address_,
                               callback.callback());
     if (rv == ERR_IO_PENDING)
       rv = callback.WaitForResult();
     if (rv < 0)
-      return "";  // error!
+      return std::string();  // error!
     return std::string(buffer_->data(), rv);
   }
 
   // Loop until |msg| has been written to the socket or until an
   // error occurs.
   // If |address| is specified, then it is used for the destination
   // to send to. Otherwise, will send to the last socket this server
   // received from.
   int SendToSocket(UDPServerSocket* socket, std::string msg) {
     return SendToSocket(socket, msg, recv_from_address_);
@@ skipping 23 matching lines @@
     return bytes_sent;
   }
 
   std::string ReadSocket(UDPClientSocket* socket) {
     TestCompletionCallback callback;
 
     int rv = socket->Read(buffer_, kMaxRead, callback.callback());
     if (rv == ERR_IO_PENDING)
       rv = callback.WaitForResult();
     if (rv < 0)
-      return "";  // error!
+      return std::string();  // error!
     return std::string(buffer_->data(), rv);
   }
 
   // Loop until |msg| has been written to the socket or until an
   // error occurs.
   int WriteSocket(UDPClientSocket* socket, std::string msg) {
     TestCompletionCallback callback;
 
     int length = msg.length();
     scoped_refptr<StringIOBuffer> io_buffer(new StringIOBuffer(msg));
@@ skipping 426 matching lines @@
   EXPECT_EQ(rv, ERR_IO_PENDING);
 
   server.Close();
 
   EXPECT_FALSE(callback.have_result());
 }
 
 }  // namespace
 
 }  // namespace net