[Not for review] Add TRACE_EVENTs and chrome://flags for preconnect

net/socket/ssl_client_socket_impl.cc

Index: net/socket/ssl_client_socket_impl.cc
diff --git a/net/socket/ssl_client_socket_impl.cc b/net/socket/ssl_client_socket_impl.cc
index 91c10da3012282f34cb23898d488dd9626b7c838..2344479466aa6f4cc3fd6f3193f7ae9a2d3d2869 100644
--- a/net/socket/ssl_client_socket_impl.cc
+++ b/net/socket/ssl_client_socket_impl.cc
@@ -1311,7 +1311,8 @@ void SSLClientSocketImpl::OnHandshakeIOComplete(int result) {
 }
 
 int SSLClientSocketImpl::DoHandshakeLoop(int last_io_result) {
-  TRACE_EVENT0(kNetTracingCategory, "SSLClientSocketImpl::DoHandshakeLoop");
+  TRACE_EVENT1("net", "SSLClientSocketImpl::DoHandshakeLoop", "host",
+               host_and_port_.host());
   int rv = last_io_result;
   do {
     // Default to STATE_NONE for next state.