Bring back SCT_STATUS_INVALID for cached entries

net/cert/sct_status_flags.h

 // Copyright 2013 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.
 
 #ifndef NET_CERT_SCT_STATUS_FLAGS_H_
 #define NET_CERT_SCT_STATUS_FLAGS_H_
 
 namespace net {
 
 namespace ct {
 
 // The possible verification statuses for a SignedCertificateTimestamp.
 // Note: The numeric values are used within histograms and should not change
 // or be re-assigned.
 enum SCTVerifyStatus {
   // Not a real status, this just prevents a default int value from being
   // mis-interpreseted as a valid status.
   // Also used to count SCTs that cannot be decoded in the histogram.
   SCT_STATUS_NONE = 0,
 
   // The SCT is from an unknown log, so we cannot verify its signature.
   SCT_STATUS_LOG_UNKNOWN = 1,
 
-  // SCTVerifyStatus=2 used to represent SCT_STATUS_INVALID, which has now been
-  // split into INVALID_SIGNATURE and INVALID_TIMESTAMP to represent the
-  // different reasons an SCT could be invalid.
+  // This value is deprecated and should not be used. It has been split
+  // into INVALID_SIGNATURE and INVALID_TIMESTAMP to represent the
+  // different reasons an SCT could be invalid. It is preserved here
+  // because SCTVerifyStatus values are serialized into the disk cache,
+  // so a previously written value of SCT_STATUS_INVALID could be read
+  // out of the disk cache.

[Ryan Sleevi, 2016/08/24 04:51:13]

Layering: net/cert doesn't know about things like "the disk cache"

// DEPRECATED: No longer in use, but may be present in serialized messages.
DEPRECATED_SCT_STATUS_INVALID = 2,

+  SCT_STATUS_INVALID = 2,
 
   // The SCT is from a known log, and the signature is valid.
   SCT_STATUS_OK = 3,
 
   // The SCT is from a known log, but the signature is invalid.
   SCT_STATUS_INVALID_SIGNATURE = 4,
 
   // The SCT is from a known log, but the timestamp is in the future.
   SCT_STATUS_INVALID_TIMESTAMP = 5,
 
   // Used to bound the enum values. Since this enum is passed over IPC,
   // the last value must be a valid one (rather than one past a valid one).
   SCT_STATUS_MAX = SCT_STATUS_INVALID_TIMESTAMP,
 };
 
 }  // namespace ct
 
 }  // namespace net
 
 #endif  // NET_CERT_SCT_STATUS_FLAGS_H_