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/test_tools/simulator/actor.cc b/quic/test_tools/simulator/actor.cc
index 546875d..578b894 100644
--- a/quic/test_tools/simulator/actor.cc
+++ b/quic/test_tools/simulator/actor.cc
@@ -8,7 +8,7 @@
 namespace quic {
 namespace simulator {
 
-Actor::Actor(Simulator* simulator, QuicString name)
+Actor::Actor(Simulator* simulator, std::string name)
     : simulator_(simulator),
       clock_(simulator->GetClock()),
       name_(std::move(name)) {