Fix |security_bits| comment on SecurityStateModel

components/security_state/security_state_model.h

 // Copyright 2015 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 COMPONENTS_SECURITY_STATE_SECURITY_STATE_MODEL_H_
 #define COMPONENTS_SECURITY_STATE_SECURITY_STATE_MODEL_H_
 
 #include "base/macros.h"
 #include "net/cert/cert_status_flags.h"
 #include "net/cert/sct_status_flags.h"
@@ skipping 90 matching lines @@
     // certificate errors.
     ContentStatus content_with_cert_errors_status;
     // The verification statuses of the signed certificate timestamps
     // for the connection.
     std::vector<net::ct::SCTVerifyStatus> sct_verify_statuses;
     bool scheme_is_cryptographic;
     net::CertStatus cert_status;
     int cert_id;
     // The security strength, in bits, of the SSL cipher suite. In late
     // 2015, 128 is considered the minimum.
-    // 0 means the connection is not encrypted.
-    // -1 means the security strength is unknown.
+    //
+    // 0 means the connection uses HTTPS but is not encrypted.  -1 means
+    // the security strength is unknown or the connection does not use
+    // HTTPS.
     int security_bits;
     // Information about the SSL connection, such as protocol and
     // ciphersuite. See ssl_connection_flags.h in net.
     int connection_status;
     // A mask that indicates which of the protocol version,
     // key exchange, or cipher for the connection is considered
     // obsolete. See net::ObsoleteSSLMask for specific mask values.
     int obsolete_ssl_status;
 
     // True if pinning was bypassed due to a local trust anchor.
@@ skipping 62 matching lines @@
   mutable VisibleSecurityState visible_security_state_;
 
   SecurityStateModelClient* client_;
 
   DISALLOW_COPY_AND_ASSIGN(SecurityStateModel);
 };
 
 }  // namespace security_state
 
 #endif  // COMPONENTS_SECURITY_STATE_SECURITY_STATE_MODEL_H_