Address David's comments.

src/core/tsi/ssl_transport_security.cc

@@ -1523,10 +1523,13 @@ static tsi_result ssl_handshaker_next(
   if (ssl_handshaker_get_result(impl) == TSI_HANDSHAKE_IN_PROGRESS) {
     *handshaker_result = nullptr;
   } else {
-    // In TLS 1.3, the ClientFinished or ServerFinished record may have
-    // (encrypted) application data appended to the end of the record. In TLS
-    // 1.2, this is explicitly disallowed by the RFC; application data will
-    // never be appended to a handshake record.
+    // In TLS 1.3, the client may send application data records in the same
+    // flight of messages as the record containing the ClientFinished message.
+    // In TLS 1.2, this is not allowed; both the client and server must complete
+    // the handshake before any application data may be sent.
+    //
+    // These application data records are removed from the BIO after the
+    // server-side handshake completes, and set to |unused_bytes|.
     unsigned char* unused_bytes = nullptr;
     size_t unused_bytes_size = 0;
     status = ssl_bytes_remaining(impl, &unused_bytes, &unused_bytes_size);

test/core/handshake/client_ssl.cc

@@ -161,9 +161,7 @@ static void server_thread(void* arg) {
   // Set the cipher list to match the one expressed in
   // src/core/tsi/ssl_transport_security.c.
   const char* cipher_list =
-      "TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_"
-      "SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-"
-      "AES256-"
+      "ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-"
       "SHA384:ECDHE-RSA-AES256-GCM-SHA384";
   if (!SSL_CTX_set_cipher_list(ctx, cipher_list)) {
     ERR_print_errors_fp(stderr);

test/core/handshake/server_ssl_common.cc

@@ -203,9 +203,8 @@ bool server_ssl_test(const char* alpn_list[], unsigned int alpn_list_len,
   // Set the cipher list to match the one expressed in
   // src/core/tsi/ssl_transport_security.c.
   const char* cipher_list =
-      "TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_"
-      "SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-"
-      "AES256-SHA384:ECDHE-RSA-AES256-GCM-SHA384";
+      "ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-"
+      "SHA384:ECDHE-RSA-AES256-GCM-SHA384";
   if (!SSL_CTX_set_cipher_list(ctx, cipher_list)) {
     ERR_print_errors_fp(stderr);
     gpr_log(GPR_ERROR, "Couldn't set server cipher list.");