Change the interface for parsing SignatureAlgorithm to take a

net/cert/internal/signature_algorithm.h

Index: net/cert/internal/signature_algorithm.h
diff --git a/net/cert/internal/signature_algorithm.h b/net/cert/internal/signature_algorithm.h
index 0942cce8354e010204580659ae3ef42213c39f0a..a184c41d1e3dd5d8ddd522a079e56e7f3262defc 100644
--- a/net/cert/internal/signature_algorithm.h
+++ b/net/cert/internal/signature_algorithm.h
@@ -15,6 +15,8 @@
 
 namespace net {
 
+class CertErrors;
+
 namespace der {
 class Input;
 }  // namespace der
@@ -87,11 +89,14 @@ class NET_EXPORT SignatureAlgorithm {
   DigestAlgorithm digest() const { return digest_; }
 
   // Creates a SignatureAlgorithm by parsing a DER-encoded "AlgorithmIdentifier"
-  // (RFC 5280). Returns nullptr on failure.
-  static std::unique_ptr<SignatureAlgorithm> CreateFromDer(
-      const der::Input& algorithm_identifier);
+  // (RFC 5280). Returns nullptr on failure. If |errors| was non-null then
+  // error/warning information is output to it.
+  static std::unique_ptr<SignatureAlgorithm> Create(

[eroman, 2016/09/17 01:18:18]

I dropped the "FromDer" from name for consistency with ParsedCert::Create().

Also the parameter type der::Input kind of already implies this if there was any
confusion.

+      const der::Input& algorithm_identifier,
+      CertErrors* errors);
 
   // Creates a new SignatureAlgorithm with the given type and parameters.
+  // Guaranteed to return non-null result.
   static std::unique_ptr<SignatureAlgorithm> CreateRsaPkcs1(
       DigestAlgorithm digest);
   static std::unique_ptr<SignatureAlgorithm> CreateEcdsa(