[HTTP Cache] Prevent memory backend from exceeding its max size

net/disk_cache/memory/mem_backend_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.
 
 // See net/disk_cache/disk_cache.h for the public interface of the cache.
 
 #ifndef NET_DISK_CACHE_MEMORY_MEM_BACKEND_IMPL_H_
 #define NET_DISK_CACHE_MEMORY_MEM_BACKEND_IMPL_H_
 
 #include <stdint.h>
@@ skipping 55 matching lines @@
 
   // Signals that an entry has been doomed, and so it should be removed from the
   // list of active entries as appropriate, as well as removed from the
   // |lru_list_|.
   void OnEntryDoomed(MemEntryImpl* entry);
 
   // Adjust the current size of this backend by |delta|. This is used to
   // determine if eviction is neccessary and when eviction is finished.
   void ModifyStorageSize(int32_t delta);
 
+  // Returns true if the cache's size is greater than the maximum allowed
+  // size.
+  bool HasExceededStorageSize() const;
+
   // Backend interface.
   net::CacheType GetCacheType() const override;
   int32_t GetEntryCount() const override;
   int OpenEntry(const std::string& key,
                 Entry** entry,
                 const CompletionCallback& callback) override;
   int CreateEntry(const std::string& key,
                   Entry** entry,
                   const CompletionCallback& callback) override;
   int DoomEntry(const std::string& key,
@@ skipping 37 matching lines @@
   net::NetLog* net_log_;
 
   base::WeakPtrFactory<MemBackendImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MemBackendImpl);
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_MEMORY_MEM_BACKEND_IMPL_H_