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

net/base/net_util.cc

Index: net/base/net_util.cc
diff --git a/net/base/net_util.cc b/net/base/net_util.cc
index 066812c18fa555f12a83df40469f3216348bd9e6..18d00fe2d02c456ab2f7c4a85d430292273fa507 100644
--- a/net/base/net_util.cc
+++ b/net/base/net_util.cc
@@ -1433,7 +1433,7 @@ std::string NetAddressToString(const struct sockaddr* sa,
   if (!GetIPAddressFromSockAddr(sa, sock_addr_len, &address,
                                 &address_len, NULL)) {
     NOTREACHED();
-    return "";
+    return std::string();
   }
   return IPAddressToString(address, address_len);
 }
@@ -1446,7 +1446,7 @@ std::string NetAddressToStringWithPort(const struct sockaddr* sa,
   if (!GetIPAddressFromSockAddr(sa, sock_addr_len, &address,
                                 &address_len, &port)) {
     NOTREACHED();
-    return "";
+    return std::string();
   }
   return IPAddressToStringWithPort(address, address_len, port);
 }