[BlobAsync] Disk support for blob storage

storage/browser/blob/blob_flattener.h

+// TODO: Insert description here. (generated by dmurph)
+
+#ifndef STORAGE_BROWSER_BLOB_BLOB_FLATTENER_H_
+#define STORAGE_BROWSER_BLOB_BLOB_FLATTENER_H_
+
+#include "base/macros.h"
+
+#include <map>
+#include <string>
+#include <utility>
+
+#include "base/numerics/safe_math.h"
+#include "storage/browser/blob/blob_slice.h"
+#include "storage/browser/blob/blob_storage_registry.h"
+
+namespace storage {
+class BlobDataBuilder;
+class InternalBlobData;
+
+struct BlobFlattener {
+ public:
+  BlobFlattener(const BlobDataBuilder& transportation_result,
+                InternalBlobData* output_blob,
+                BlobStorageRegistry* registry);
+  ~BlobFlattener();
+
+  bool contains_broken_references = false;
+  bool contains_pending_content = false;
+  base::CheckedNumeric<uint64_t> total_size;
+  base::CheckedNumeric<uint64_t> memory_needed;
+  std::vector<std::pair<std::string, BlobStorageRegistry::Entry*>>
+      dependent_blobs;
+  std::vector<BlobStorageRegistry::ItemCopyEntry> copies;
+};
+
+}  // namespace storage
+#endif  // STORAGE_BROWSER_BLOB_BLOB_FLATTENER_H_