Purge in-memory localStorage areas if the # of areas exceeds the limit

webkit/dom_storage/dom_storage_cached_area.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_CACHED_AREA_H_
 #define WEBKIT_DOM_STORAGE_DOM_STORAGE_CACHED_AREA_H_
 
 #include <map>
 
 #include "base/memory/ref_counted.h"
@@ skipping 10 matching lines @@
 // Unlike the other classes in the dom_storage library, this one is intended
 // for use in renderer processes. It maintains a complete cache of the
 // origin's Map of key/value pairs for fast access. The cache is primed on
 // first access and changes are written to the backend thru the |proxy|.
 // Mutations originating in other processes are applied to the cache via
 // the ApplyMutation method.
 class WEBKIT_STORAGE_EXPORT DomStorageCachedArea :
       public base::RefCounted<DomStorageCachedArea> {
  public:
   DomStorageCachedArea(int64 namespace_id, const GURL& origin,
-                       DomStorageProxy* proxy);
+                       DomStorageProxy* proxy,
+                       int64 storage_size);
 
   int64 namespace_id() const { return namespace_id_; }
   const GURL& origin() const { return origin_; }
 
   unsigned GetLength(int connection_id);
   NullableString16 GetKey(int connection_id, unsigned index);
   NullableString16 GetItem(int connection_id, const string16& key);
   bool SetItem(int connection_id, const string16& key, const string16& value,
                const GURL& page_url);
   void RemoveItem(int connection_id, const string16& key,
                   const GURL& page_url);
   void Clear(int connection_id, const GURL& page_url);
 
   void ApplyMutation(const NullableString16& key,
                      const NullableString16& new_value);
 
   size_t MemoryBytesUsedByCache() const;
 
+  void set_global_storage_size(int64 size) {
+    global_storage_size_ = size;
+  }
+
  private:
   friend class DomStorageCachedAreaTest;
   friend class base::RefCounted<DomStorageCachedArea>;
   ~DomStorageCachedArea();
 
   // Primes the cache, loading all values for the area.
   void Prime(int connection_id);
   void PrimeIfNeeded(int connection_id) {
     if (!map_)
       Prime(connection_id);
@@ skipping 16 matching lines @@
   }
 
   bool ignore_all_mutations_;
   std::map<string16, int> ignore_key_mutations_;
 
   int64 namespace_id_;
   GURL origin_;
   scoped_refptr<DomStorageMap> map_;
   scoped_refptr<DomStorageProxy> proxy_;
   base::WeakPtrFactory<DomStorageCachedArea> weak_factory_;
+
+  int64 global_storage_size_;
 };
 
 }  // namespace dom_storage
 
 #endif  // WEBKIT_DOM_STORAGE_DOM_STORAGE_CACHED_AREA_H_