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/http/quic_spdy_client_session.h b/quic/core/http/quic_spdy_client_session.h
index c92753b..3bb8168 100644
--- a/quic/core/http/quic_spdy_client_session.h
+++ b/quic/core/http/quic_spdy_client_session.h
@@ -43,7 +43,7 @@
   QuicCryptoClientStreamBase* GetMutableCryptoStream() override;
   const QuicCryptoClientStreamBase* GetCryptoStream() const override;
 
-  bool IsAuthorized(const QuicString& authority) override;
+  bool IsAuthorized(const std::string& authority) override;
 
   // QuicSpdyClientSessionBase methods:
   void OnProofValid(const QuicCryptoClientConfig::CachedState& cached) override;