Add GetSystemNSSKeySlot, merge GetPrivateNSSKeySlot/GetPublicNSSKeySlot to GetPersistentNSSKeySlot.

net/base/keygen_handler_nss.cc

 // 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.
 
 #include "net/base/keygen_handler.h"
 
 #include "base/logging.h"
 #include "crypto/nss_crypto_module_delegate.h"
 #include "crypto/nss_util.h"
 #include "crypto/nss_util_internal.h"
 #include "crypto/scoped_nss_types.h"
 #include "net/third_party/mozilla_security_manager/nsKeygenHandler.h"
 
 // PSM = Mozilla's Personal Security Manager.
 namespace psm = mozilla_security_manager;
 
 namespace net {
 
 std::string KeygenHandler::GenKeyAndSignChallenge() {
   // Ensure NSS is initialized.
   crypto::EnsureNSSInit();
 
   crypto::ScopedPK11Slot slot;
   if (crypto_module_delegate_)
     slot = crypto_module_delegate_->RequestSlot().Pass();
   else
-    slot.reset(crypto::GetPrivateNSSKeySlot());
+    slot.reset(crypto::GetPersistentNSSKeySlot());
   if (!slot.get()) {
     LOG(ERROR) << "Couldn't get private key slot from NSS!";
     return std::string();
   }
 
   // Authenticate to the token.
   if (SECSuccess !=
       PK11_Authenticate(
           slot.get(),
           PR_TRUE,
           crypto_module_delegate_ ? crypto_module_delegate_->wincx() : NULL)) {
     LOG(ERROR) << "Couldn't authenticate to private key slot!";
     return std::string();
   }
 
   return psm::GenKeyAndSignChallenge(key_size_in_bits_, challenge_, url_,
                                      slot.get(), stores_key_);
 }
 
 void KeygenHandler::set_crypto_module_delegate(
       scoped_ptr<crypto::NSSCryptoModuleDelegate> delegate) {
   crypto_module_delegate_ = delegate.Pass();
 }
 
 }  // namespace net