Reland: Refactor and shorten in-memory cache.

net/disk_cache/memory/mem_rankings.h

-// Copyright (c) 2010 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.
-
-#ifndef NET_DISK_CACHE_MEMORY_MEM_RANKINGS_H_
-#define NET_DISK_CACHE_MEMORY_MEM_RANKINGS_H_
-
-#include "base/macros.h"
-
-namespace disk_cache {
-
-class MemEntryImpl;
-
-// This class handles the ranking information for the memory-only cache.
-class MemRankings {
- public:
-  MemRankings() : head_(NULL), tail_(NULL) {}
-  ~MemRankings();
-
-  // Inserts a given entry at the head of the queue.
-  void Insert(MemEntryImpl* node);
-
-  // Removes a given entry from the LRU list.
-  void Remove(MemEntryImpl* node);
-
-  // Moves a given entry to the head.
-  void UpdateRank(MemEntryImpl* node);
-
-  // Iterates through the list.
-  MemEntryImpl* GetNext(MemEntryImpl* node);
-  MemEntryImpl* GetPrev(MemEntryImpl* node);
-
- private:
-  MemEntryImpl* head_;
-  MemEntryImpl* tail_;
-
-  DISALLOW_COPY_AND_ASSIGN(MemRankings);
-};
-
-}  // namespace disk_cache
-
-#endif  // NET_DISK_CACHE_MEMORY_MEM_RANKINGS_H_