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

net/disk_cache/blockfile/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_BLOCKFILE_BACKEND_IMPL_H_
 #define NET_DISK_CACHE_BLOCKFILE_BACKEND_IMPL_H_
 
 #include <stdint.h>
@@ skipping 276 matching lines @@
   // the last_used field of the entry, and therefore it does not impact the
   // eviction ranking of the entry. However, an enumeration will go through all
   // entries on the cache only if the cache is not modified while the
   // enumeration is taking place. Significantly altering the entry pointed by
   // the iterator (for example, deleting the entry) will invalidate the
   // iterator. Performing operations on an entry that modify the entry may
   // result in loops in the iteration, skipped entries or similar.
   std::unique_ptr<Iterator> CreateIterator() override;
   void GetStats(StatsItems* 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:
   using EntriesMap = std::unordered_map<CacheAddr, EntryImpl*>;
   class IteratorImpl;
 
   // Creates a new backing file for the cache index.
   bool CreateBackingStore(disk_cache::File* file);
   bool InitBackingStore(bool* file_created);
   void AdjustMaxCacheSize(int table_len);
 
@@ skipping 105 matching lines @@
   base::WaitableEvent done_;  // Signals the end of background work.
   scoped_refptr<TraceObject> trace_object_;  // Initializes internal tracing.
   base::WeakPtrFactory<BackendImpl> ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BackendImpl);
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_BLOCKFILE_BACKEND_IMPL_H_