Switch various things to scopers.

Clear out some of the easy cases.

Bug: 132
Change-Id: Icd5c246cb6bec4a96c72eccd6569235c3d030ebd
Reviewed-on: https://boringssl-review.googlesource.com/18204
Commit-Queue: Steven Valdez <svaldez@google.com>
Reviewed-by: Steven Valdez <svaldez@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/tls13_client.cc b/ssl/tls13_client.cc
index 5e2b03e..516dd3d 100644
--- a/ssl/tls13_client.cc
+++ b/ssl/tls13_client.cc
@@ -632,11 +632,11 @@
       return ssl_hs_channel_id_lookup;
     }
 
-    CBB cbb, body;
-    if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_CHANNEL_ID) ||
+    ScopedCBB cbb;
+    CBB body;
+    if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CHANNEL_ID) ||
         !tls1_write_channel_id(hs, &body) ||
-        !ssl_add_message_cbb(ssl, &cbb)) {
-      CBB_cleanup(&cbb);
+        !ssl_add_message_cbb(ssl, cbb.get())) {
       return ssl_hs_error;
     }
   }