Replace QuicString with std::string, pass 1

This replaces QuicString with std::string in all of the "QUIC proper".  I will
delete QuicString once all code using it is gone.

gfe-relnote: n/a (no functional change)
PiperOrigin-RevId: 237872023
Change-Id: I82de62c9855516b15039734d05155917e68ff4ee
diff --git a/quic/core/quic_server_id.cc b/quic/core/quic_server_id.cc
index ab35d6e..43b94b1 100644
--- a/quic/core/quic_server_id.cc
+++ b/quic/core/quic_server_id.cc
@@ -14,10 +14,10 @@
 
 QuicServerId::QuicServerId() : QuicServerId("", 0, false) {}
 
-QuicServerId::QuicServerId(const QuicString& host, uint16_t port)
+QuicServerId::QuicServerId(const std::string& host, uint16_t port)
     : QuicServerId(host, port, false) {}
 
-QuicServerId::QuicServerId(const QuicString& host,
+QuicServerId::QuicServerId(const std::string& host,
                            uint16_t port,
                            bool privacy_mode_enabled)
     : host_(host), port_(port), privacy_mode_enabled_(privacy_mode_enabled) {}