Implement SHA-256 fingerprint support

net/base/cert_verify_result.h

Index: net/base/cert_verify_result.h
===================================================================
--- net/base/cert_verify_result.h	(revision 150362)
+++ net/base/cert_verify_result.h	(working copy)
@@ -45,10 +45,15 @@
   bool has_md5_ca;
   bool has_md2_ca;
 
-  // If the certificate was successfully verified then this contains the SHA1
-  // fingerprints of the SubjectPublicKeyInfos of the chain. The fingerprint
-  // from the leaf certificate will be the first element of the vector.
-  std::vector<SHA1Fingerprint> public_key_hashes;
+  // If the certificate was successfully verified then this contains the
+  // fingerprints, in several hash algorithms, of the SubjectPublicKeyInfos
+  // of the chain. The fingerprint from the leaf certificate will be the
+  // first element of each sub-vector.
+  //
+  // This is a vector of vectors: Index the outer vector with
+  // FingerprintTag, and then the inner HashValueVectors will be
+  // fingerprints made with the algorithm named by the FingerprintTag.
+  std::vector<HashValueVector> public_key_hashes;
 
   // is_issued_by_known_root is true if we recognise the root CA as a standard
   // root.  If it isn't then it's probably the case that this certificate was