Switch to using the async DomStorage IPC messages and add a caching layer …

webkit/dom_storage/dom_storage_types.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 WEBKIT_DOM_STORAGE_DOM_STORAGE_TYPES_H_
 #define WEBKIT_DOM_STORAGE_DOM_STORAGE_TYPES_H_
 #pragma once
 
 #include <map>
 
 #include "base/basictypes.h"
 #include "base/nullable_string16.h"
 #include "base/string16.h"
 
 namespace dom_storage {
 
 // The quota for each storage area. Suggested by the spec.
+// This value is enforced in renderer processes.
 const size_t kPerAreaQuota = 5 * 1024 * 1024;
 
+// In the browser process we allow some overage to
+// accomodate concurrent writes from different renderers
+// that were allowed because the limit imposed in the renderer
+// wasn't exceeded.
+const size_t kPerAreaOverQuotaAllowance = 100 * 1024;
+
 // Value to indicate the localstorage namespace vs non-zero
 // values for sessionstorage namespaces.
 const int64 kLocalStorageNamespaceId = 0;
 
 const int64 kInvalidSessionStorageNamespaceId = kLocalStorageNamespaceId;
 
 // Value to indicate an area that not be opened.
 const int kInvalidAreaId = -1;
 
 typedef std::map<string16, NullableString16> ValuesMap;
 
 }  // namespace dom_storage
 
 #endif  // WEBKIT_DOM_STORAGE_DOM_STORAGE_TYPES_H_