Add most of the metadata-handling code for blobs. It's not quite all there, but

content/browser/indexed_db/indexed_db_backing_store.h

Index: content/browser/indexed_db/indexed_db_backing_store.h
diff --git a/content/browser/indexed_db/indexed_db_backing_store.h b/content/browser/indexed_db/indexed_db_backing_store.h
index e9ff5f6e92055cd12228d8894878fe2ca8c5cdaf..0ddf8cea0e1a973de3226e6559ffdf189688b59f 100644
--- a/content/browser/indexed_db/indexed_db_backing_store.h
+++ b/content/browser/indexed_db/indexed_db_backing_store.h
@@ -264,6 +264,8 @@ class CONTENT_EXPORT IndexedDBBackingStore
 
   base::FilePath GetBlobFileName(int64 database_id, int64 key);
 
+  class Transaction;
+
   class Cursor {
    public:
     virtual ~Cursor();
@@ -308,7 +310,9 @@ class CONTENT_EXPORT IndexedDBBackingStore
     virtual bool LoadCurrentRow() = 0;
 
    protected:
-    Cursor(LevelDBTransaction* transaction,
+    Cursor(scoped_refptr<IndexedDBBackingStore> backing_store,
+           Transaction* transaction,
+           int64 database_id,
            const CursorOptions& cursor_options);
     explicit Cursor(const IndexedDBBackingStore::Cursor* other);
 
@@ -319,7 +323,9 @@ class CONTENT_EXPORT IndexedDBBackingStore
     bool IsPastBounds() const;
     bool HaveEnteredRange() const;
 
-    LevelDBTransaction* transaction_;
+    IndexedDBBackingStore* backing_store_;

[jsbell, 2014/05/06 00:24:16]

We should probably update the ownership graph soon:

https://docs.google.com/a/chromium.org/drawings/d/1JBGlUYkJMJKT5KyIz0h34RxRIl...

[ericu, 2014/05/06 17:26:20]

Updated.  There's nothing in the key about what colors mean, though, so they may
need correction.

+    Transaction* transaction_;
+    int64 database_id_;
     const CursorOptions cursor_options_;
     scoped_ptr<LevelDBIterator> iterator_;
     scoped_ptr<IndexedDBKey> current_key_;
@@ -399,6 +405,11 @@ class CONTENT_EXPORT IndexedDBBackingStore
 
     LevelDBTransaction* transaction() { return transaction_; }
 
+    leveldb::Status GetBlobInfoForRecord(
+        int64 database_id,
+        const std::string& object_store_data_key,
+        IndexedDBValue* value);
+
     // This holds a BlobEntryKey and the encoded IndexedDBBlobInfo vector stored
     // under that key.
     typedef std::vector<std::pair<BlobEntryKey, std::string> >
@@ -475,6 +486,8 @@ class CONTENT_EXPORT IndexedDBBackingStore
 
   bool is_incognito() const { return !indexed_db_factory_; }
 
+  bool SetUpMetadata();
+
   virtual bool WriteBlobFile(
       int64 database_id,
       const Transaction::WriteDescriptor& descriptor,