Persist sessionStorage on disk.

content/browser/dom_storage/session_storage_namespace_impl.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 CONTENT_BROWSER_DOM_STORAGE_SESSION_STORAGE_NAMESPACE_IMPL_H_
 #define CONTENT_BROWSER_DOM_STORAGE_SESSION_STORAGE_NAMESPACE_IMPL_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/session_storage_namespace.h"
+#include "webkit/dom_storage/dom_storage_context.h"
 
 class DOMStorageContextImpl;
 
 namespace dom_storage {
 class DomStorageSession;
 }
 
+struct SessionStorageAssociatedDetails {
+  int64 id;
+  int real_id;
+  SessionStorageAssociatedDetails();
+  SessionStorageAssociatedDetails(int64 id, int64 real_id);
+  ~SessionStorageAssociatedDetails();
+};
+
 class SessionStorageNamespaceImpl
-    : NON_EXPORTED_BASE(public content::SessionStorageNamespace) {
+    : NON_EXPORTED_BASE(public content::SessionStorageNamespace),
+      public dom_storage::DomStorageContext::SessionStorageObserver {
  public:
   explicit SessionStorageNamespaceImpl(DOMStorageContextImpl* context);
-  int64 id() const;
+  virtual int64 id() const;
   SessionStorageNamespaceImpl* Clone();
 
+  virtual void OnSessionStorageNamespaceAssociated(
+      int64 real_namespace_id);
+
  private:
   explicit SessionStorageNamespaceImpl(dom_storage::DomStorageSession* clone);
   virtual ~SessionStorageNamespaceImpl();
 
   scoped_refptr<dom_storage::DomStorageSession> session_;
 
   DISALLOW_COPY_AND_ASSIGN(SessionStorageNamespaceImpl);
 };
 
 #endif  // CONTENT_BROWSER_DOM_STORAGE_SESSION_STORAGE_NAMESPACE_IMPL_H_