[HttpCache] Store some memcache info to memory dumps for debugging

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 80 matching lines @@
   int DoomEntriesSince(base::Time initial_time,
                        const CompletionCallback& callback) override;
   int CalculateSizeOfAllEntries(const CompletionCallback& callback) override;
   int CalculateSizeOfEntriesBetween(
       base::Time initial_time,
       base::Time end_time,
       const CompletionCallback& callback) override;
   std::unique_ptr<Iterator> CreateIterator() override;
   void GetStats(base::StringPairs* stats) override {}
   void OnExternalCacheHit(const std::string& key) override;
-  size_t EstimateMemoryUsage() const override;
+  size_t DumpMemoryStats(
+      base::trace_event::ProcessMemoryDump* pmd,
+      const std::string& parent_absolute_name) const override;
 
  private:
   class MemIterator;
   friend class MemIterator;
 
   using EntryMap = std::unordered_map<std::string, MemEntryImpl*>;
 
   // Deletes entries from the cache until the current size is below the limit.
   void EvictIfNeeded();
 
   EntryMap entries_;
 
   // Stored in increasing order of last use time, from least recently used to
   // most recently used.
   base::LinkedList<MemEntryImpl> lru_list_;
 
   int32_t max_size_;      // Maximum data size for this instance.
   int32_t current_size_;
 
   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_