Extract the certificate to use in the download protection pingback.

chrome/common/safe_browsing/csd.proto

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Client side phishing and malware detection request and response
 // protocol buffers.  Those protocol messages should be kept in sync
 // with the server implementation.
 //
 // If you want to change this protocol definition or you have questions
 // regarding its format please contact chrome-anti-phishing@googlegroups.com.
@@ skipping 107 matching lines @@
 
     // TODO(noelutz): add the transition type?
   }
 
   // This repeated field will store all the redirects as well as the
   // final URLs for the top-level tab URL (i.e., the URL that
   // triggered the download) as well as for the download URL itself.
   repeated Resource resources = 4;
 
   message SignatureInfo {
-    // If the binary is signed this will contain the name of the certificate
-    // authority that signed the binary.  The format of that field is TBD.
-    optional bytes certificate_issuer = 1;
+    // The full DER-encoded X.509 certificate extracted from the binary.
+    // If this field is not present, it means the binary was unsigned.
+    optional bytes certificate_contents = 1;
 
-    // Serial number of the certificate autority.  This value uniquely
-    // identifies the certificate authority.
-    optional bytes certificate_serial_number = 2;
-
-    // Name of the company / organization the ceritificate was issued to.
-    optional bytes certificate_subject = 3;
-
-    // The full DER-encoded X.509 certificate extracted from the binary.
-    optional bytes certificate_contents = 4;
+    // True if the signature was trusted on the client.
+    optional bool trusted = 2;
   }
 
   // This field will only be set if the binary is signed.
   optional SignatureInfo signature = 5;
 
   // True if the download was user initiated.
   optional bool user_initiated = 6;
 }
 
 message ClientDownloadResponse {
   enum Verdict {
     // Download is considered safe.
     SAFE = 0;
     // Download is considered dangerous.  Chrome should show a warning to the
     // user.
     DANGEROUS = 1;
   }
   required Verdict verdict = 1;
 }