Add helper functions for info_callback and msg_callback.

This is getting a little repetitive.

Change-Id: Ib0fa8ab10149557c2d728b88648381b9368221d9
Reviewed-on: https://boringssl-review.googlesource.com/8126
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/ssl/tls_record.c b/ssl/tls_record.c
index 45d9940..7036c87 100644
--- a/ssl/tls_record.c
+++ b/ssl/tls_record.c
@@ -226,10 +226,8 @@
     return ssl_open_record_partial;
   }
 
-  if (ssl->msg_callback != NULL) {
-    ssl->msg_callback(0 /* read */, 0, SSL3_RT_HEADER, in,
-                      SSL3_RT_HEADER_LENGTH, ssl, ssl->msg_callback_arg);
-  }
+  ssl_do_msg_callback(ssl, 0 /* read */, 0, SSL3_RT_HEADER, in,
+                      SSL3_RT_HEADER_LENGTH);
 
   /* Decrypt the body. */
   size_t plaintext_len;
@@ -335,11 +333,8 @@
 
   *out_len = SSL3_RT_HEADER_LENGTH + ciphertext_len;
 
-  if (ssl->msg_callback) {
-    ssl->msg_callback(1 /* write */, 0, SSL3_RT_HEADER, out,
-                      SSL3_RT_HEADER_LENGTH, ssl, ssl->msg_callback_arg);
-  }
-
+  ssl_do_msg_callback(ssl, 1 /* write */, 0, SSL3_RT_HEADER, out,
+                      SSL3_RT_HEADER_LENGTH);
   return 1;
 }