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/crypto/crypto_message_parser.h b/quic/core/crypto/crypto_message_parser.h
index 8b9fa4a..3c70e6e 100644
--- a/quic/core/crypto/crypto_message_parser.h
+++ b/quic/core/crypto/crypto_message_parser.h
@@ -17,7 +17,7 @@
   virtual ~CryptoMessageParser() {}
 
   virtual QuicErrorCode error() const = 0;
-  virtual const QuicString& error_detail() const = 0;
+  virtual const std::string& error_detail() const = 0;
 
   // Processes input data, which must be delivered in order. The input data
   // being processed was received at encryption level |level|. Returns