Revert of Remove reference counting from HttpNetworkSession.

ios/crnet/crnet_environment.mm

Index: ios/crnet/crnet_environment.mm
diff --git a/ios/crnet/crnet_environment.mm b/ios/crnet/crnet_environment.mm
index 516d2e86c45f2c7254089a862f1598bded1051b1..3eb873a1f081d1778b2e7c67710d9d22230e8ef6 100644
--- a/ios/crnet/crnet_environment.mm
+++ b/ios/crnet/crnet_environment.mm
@@ -446,12 +446,7 @@
         base::WorkerPool::GetTaskRunner(true));
   }
 
-  // TODO(mmenke):  These really shouldn't be leaked.
-  //                See https://crbug.com/523858.
-  net::HttpNetworkSession* http_network_session =
-      new net::HttpNetworkSession(params);
-  net::HttpCache* main_cache = new net::HttpCache(
-      http_network_session, main_backend, true /* set_up_quic_server_info */);
+  net::HttpCache* main_cache = new net::HttpCache(params, main_backend);
   main_context_->set_http_transaction_factory(main_cache);
 
   // Cookies