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/quartc/simulated_packet_transport.cc b/quic/quartc/simulated_packet_transport.cc
index 5c0d374..8e82d98 100644
--- a/quic/quartc/simulated_packet_transport.cc
+++ b/quic/quartc/simulated_packet_transport.cc
@@ -10,8 +10,8 @@
 
 SimulatedQuartcPacketTransport::SimulatedQuartcPacketTransport(
     Simulator* simulator,
-    const QuicString& name,
-    const QuicString& peer_name,
+    const std::string& name,
+    const std::string& peer_name,
     QuicByteCount queue_capacity)
     : Endpoint(simulator, name),
       peer_name_(peer_name),
@@ -34,7 +34,7 @@
   last_packet_number_ = info.packet_number;
 
   auto packet = QuicMakeUnique<Packet>();
-  packet->contents = QuicString(buffer, buf_len);
+  packet->contents = std::string(buffer, buf_len);
   packet->size = buf_len;
   packet->tx_timestamp = clock_->Now();
   packet->source = name();