Replace most explicit `new RefCountedObject...` with make_ref_counted

Bug: webrtc:12701
Change-Id: Iab91f1e96715eed7f9ddcfe1ca55510a18c817eb
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/224544
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35786}
diff --git a/examples/unityplugin/unity_plugin_apis.cc b/examples/unityplugin/unity_plugin_apis.cc
index 34c28d9..672330f 100644
--- a/examples/unityplugin/unity_plugin_apis.cc
+++ b/examples/unityplugin/unity_plugin_apis.cc
@@ -27,7 +27,7 @@
                          const char* credential,
                          bool mandatory_receive_video) {
   g_peer_connection_map[g_peer_connection_id] =
-      new rtc::RefCountedObject<SimplePeerConnection>();
+      rtc::make_ref_counted<SimplePeerConnection>();
 
   if (!g_peer_connection_map[g_peer_connection_id]->InitializePeerConnection(
           turn_urls, no_of_urls, username, credential, mandatory_receive_video))