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

net/disk_cache/blockfile/backend_impl.h

Index: net/disk_cache/blockfile/backend_impl.h
diff --git a/net/disk_cache/blockfile/backend_impl.h b/net/disk_cache/blockfile/backend_impl.h
index e095d93cb2e19bfb175faeaec2f05d56cf3255be..f1c124ed9b3e4e42632b3eeee6d385fa9ea25614 100644
--- a/net/disk_cache/blockfile/backend_impl.h
+++ b/net/disk_cache/blockfile/backend_impl.h
@@ -294,7 +294,9 @@ class NET_EXPORT_PRIVATE BackendImpl : public Backend {
   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*>;