Persist sessionStorage on disk.

content/browser/dom_storage/session_storage_namespace_impl.cc

 // 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.
 
 #include "content/browser/dom_storage/session_storage_namespace_impl.h"
 
 #include "content/browser/dom_storage/dom_storage_context_impl.h"
 #include "webkit/dom_storage/dom_storage_session.h"
 
 using dom_storage::DomStorageContext;
 using dom_storage::DomStorageSession;
 
 SessionStorageNamespaceImpl::SessionStorageNamespaceImpl(
     DOMStorageContextImpl* context)
     : session_(new DomStorageSession(context->context())) {
 }
 
 SessionStorageNamespaceImpl::SessionStorageNamespaceImpl(
     DOMStorageContextImpl* context, int64 namepace_id_to_clone)
     : session_(DomStorageSession::CloneFrom(context->context(),
                                             namepace_id_to_clone)) {
 }
 
+SessionStorageNamespaceImpl::SessionStorageNamespaceImpl(
+    DOMStorageContextImpl* context, const std::string& persistent_id)
+    : session_(new DomStorageSession(context->context(),
+                                     persistent_id)) {
+}
+
 int64 SessionStorageNamespaceImpl::id() const {
   return session_->namespace_id();
 }
 
+std::string SessionStorageNamespaceImpl::persistent_id() const {
+  return session_->persistent_namespace_id();
+}
+
 SessionStorageNamespaceImpl* SessionStorageNamespaceImpl::Clone() {
   return new SessionStorageNamespaceImpl(session_->Clone());
 }
 
 SessionStorageNamespaceImpl::SessionStorageNamespaceImpl(
     DomStorageSession* clone)
     : session_(clone) {
 }
 
 SessionStorageNamespaceImpl::~SessionStorageNamespaceImpl() {
 }