Rely on new bssl::Span-like APIs in der::Input

This starts removing some of the dependencies in Chromium on der::Input
being its own bespoke type.

https://boringssl.googlesource.com/boringssl/+/90ceeb021579cdec2c1dd663a5f993e7161f5082

Bug: boringssl:661
Change-Id: Idb500a24b0c0a13c50696845565d8c85cf98ed92
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5240257
Reviewed-by: Ali Juma <ajuma@chromium.org>
Reviewed-by: Matt Mueller <mattm@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: David Benjamin <davidben@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1253641}
NOKEYCHECK=True
GitOrigin-RevId: e544cb8b03ff7cd9c65654f3a8b48ec2340125f6
diff --git a/ssl/cmpcert.cc b/ssl/cmpcert.cc
index 5a0eb66..4dd82a5 100644
--- a/ssl/cmpcert.cc
+++ b/ssl/cmpcert.cc
@@ -90,8 +90,8 @@
 
     // Look the parent up in the database and keep searching.
     SECItem issuer_item;
-    issuer_item.len = issuer.Length();
-    issuer_item.data = const_cast<unsigned char*>(issuer.UnsafeData());
+    issuer_item.len = issuer.size();
+    issuer_item.data = const_cast<unsigned char*>(issuer.data());
     ScopedCERTCertificate nextcert(
         CERT_FindCertByName(CERT_GetDefaultCertDB(), &issuer_item));
     if (!nextcert)