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_stream.cc b/quic/core/quic_stream.cc
index 86207b6..91dace4 100644
--- a/quic/core/quic_stream.cc
+++ b/quic/core/quic_stream.cc
@@ -76,7 +76,7 @@
 }
 
 void PendingStream::CloseConnectionWithDetails(QuicErrorCode error,
-                                               const QuicString& details) {
+                                               const std::string& details) {
   session_->connection()->CloseConnection(
       error, details, ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
 }
@@ -402,7 +402,7 @@
 }
 
 void QuicStream::CloseConnectionWithDetails(QuicErrorCode error,
-                                            const QuicString& details) {
+                                            const std::string& details) {
   session()->connection()->CloseConnection(
       error, details, ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
 }