Make the private slot optional in NSSCertDatabase.

net/cert/nss_cert_database.h

 // Copyright (c) 2012 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_NSS_CERT_DATABASE_H_
 #define NET_CERT_NSS_CERT_DATABASE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 89 matching lines @@
 
   typedef base::Callback<void(bool)> DeleteCertCallback;
 
   // Creates a NSSCertDatabase that will store public information (such as
   // certificates and trust records) in |public_slot|, and private information
   // (such as keys) in |private_slot|.
   // In general, code should avoid creating an NSSCertDatabase directly,
   // as doing so requires making opinionated decisions about where to store
   // data, and instead prefer to be passed an existing NSSCertDatabase
   // instance.
-  // Both slots must not be NULL but can be identical.
+  // |public_slot| must not be NULL, |private_slot| can be NULL. Both slots can
+  // be identical.
   NSSCertDatabase(crypto::ScopedPK11Slot public_slot,
                   crypto::ScopedPK11Slot private_slot);
   virtual ~NSSCertDatabase();
 
   // Get a list of unique certificates in the certificate database (one
   // instance of all certificates).
   // DEPRECATED by |ListCerts|. See http://crbug.com/340460.
   virtual void ListCertsSync(CertificateList* certs);
 
   // Asynchronously get a list of unique certificates in the certificate
@@ skipping 16 matching lines @@
   // this call returns synchronously. Thus, it is possible to call this function
   // before SetSystemSlot is called and get a NULL result.
   // See https://crbug.com/399554 .
   virtual crypto::ScopedPK11Slot GetSystemSlot() const;
 #endif
 
   // Get the default slot for public key data.
   crypto::ScopedPK11Slot GetPublicSlot() const;
 
   // Get the default slot for private key or mixed private/public key data.
+  // Can return NULL.
   crypto::ScopedPK11Slot GetPrivateSlot() const;
 
   // Get the default module for public key data.
   // The returned pointer must be stored in a scoped_refptr<CryptoModule>.
   // DEPRECATED: use GetPublicSlot instead.
   // TODO(mattm): remove usage of this method and remove it.
   CryptoModule* GetPublicModule() const;
 
   // Get the default module for private key or mixed private/public key data.
   // The returned pointer must be stored in a scoped_refptr<CryptoModule>.
@@ skipping 144 matching lines @@
   const scoped_refptr<ObserverListThreadSafe<Observer> > observer_list_;
 
   base::WeakPtrFactory<NSSCertDatabase> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NSSCertDatabase);
 };
 
 }  // namespace net
 
 #endif  // NET_CERT_NSS_CERT_DATABASE_H_