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

jingle/notifier/communicator/single_login_attempt.cc

Index: jingle/notifier/communicator/single_login_attempt.cc
diff --git a/jingle/notifier/communicator/single_login_attempt.cc b/jingle/notifier/communicator/single_login_attempt.cc
index dda0cfe15b5d6038dc46a0ab8dba86026a461c7e..49fcdee6745de7ed709d907a2dc9bf2266607844 100644
--- a/jingle/notifier/communicator/single_login_attempt.cc
+++ b/jingle/notifier/communicator/single_login_attempt.cc
@@ -85,9 +85,9 @@ net::HostPortPair ParseRedirectText(const std::string& redirect_text) {
 void SingleLoginAttempt::OnError(buzz::XmppEngine::Error error, int subcode,
                                  const buzz::XmlElement* stream_error) {
   DVLOG(1) << "Error: " << error << ", subcode: " << subcode
-           << (stream_error ?
-               (", stream error: " + XmlElementToString(*stream_error)) :
-               "");
+           << (stream_error
+                   ? (", stream error: " + XmlElementToString(*stream_error))
+                   : std::string());
 
   DCHECK_EQ(error == buzz::XmppEngine::ERROR_STREAM, stream_error != NULL);