Delete AsyncSocket class, merge into Socket class

Bug: webrtc:13065
Change-Id: I13afee2386ea9c4de0e4fa95133f0c4d3ec826e8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227031
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34787}
diff --git a/rtc_base/test_echo_server.cc b/rtc_base/test_echo_server.cc
index d2e11d6..feda4cd 100644
--- a/rtc_base/test_echo_server.cc
+++ b/rtc_base/test_echo_server.cc
@@ -15,8 +15,8 @@
 namespace rtc {
 
 TestEchoServer::TestEchoServer(Thread* thread, const SocketAddress& addr)
-    : server_socket_(thread->socketserver()->CreateAsyncSocket(addr.family(),
-                                                               SOCK_STREAM)) {
+    : server_socket_(
+          thread->socketserver()->CreateSocket(addr.family(), SOCK_STREAM)) {
   server_socket_->Bind(addr);
   server_socket_->Listen(5);
   server_socket_->SignalReadEvent.connect(this, &TestEchoServer::OnAccept);