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

remoting/host/register_support_host_request_unittest.cc

Index: remoting/host/register_support_host_request_unittest.cc
diff --git a/remoting/host/register_support_host_request_unittest.cc b/remoting/host/register_support_host_request_unittest.cc
index cd5da6e7bbaf35e87c40581a51ac76c51b58dcde..60803040f042eb02a903680a0c639cae6e5ee95f 100644
--- a/remoting/host/register_support_host_request_unittest.cc
+++ b/remoting/host/register_support_host_request_unittest.cc
@@ -99,9 +99,9 @@ TEST_F(RegisterSupportHostRequestTest, Send) {
   scoped_ptr<XmlElement> stanza(sent_iq);
   ASSERT_TRUE(stanza != NULL);
 
-  EXPECT_EQ(stanza->Attr(buzz::QName("", "to")),
+  EXPECT_EQ(stanza->Attr(buzz::QName(std::string(), "to")),
             std::string(kTestBotJid));
-  EXPECT_EQ(stanza->Attr(buzz::QName("", "type")), "set");
+  EXPECT_EQ(stanza->Attr(buzz::QName(std::string(), "type")), "set");
 
   EXPECT_EQ(QName(kChromotingXmlNamespace, "register-support-host"),
             stanza->FirstElement()->Name());
@@ -131,9 +131,9 @@ TEST_F(RegisterSupportHostRequestTest, Send) {
                                     base::TimeDelta::FromSeconds(300)));
 
   scoped_ptr<XmlElement> response(new XmlElement(buzz::QN_IQ));
-  response->AddAttr(QName("", "from"), kTestBotJid);
-  response->AddAttr(QName("", "type"), "result");
-  response->AddAttr(QName("", "id"), kStanzaId);
+  response->AddAttr(QName(std::string(), "from"), kTestBotJid);
+  response->AddAttr(QName(std::string(), "type"), "result");
+  response->AddAttr(QName(std::string(), "id"), kStanzaId);
 
   XmlElement* result = new XmlElement(
       QName(kChromotingXmlNamespace, "register-support-host-result"));