Add the backchannel for Blobs to be received into Blink from the database backend.

Source/modules/indexeddb/IDBDatabase.h

Index: Source/modules/indexeddb/IDBDatabase.h
diff --git a/Source/modules/indexeddb/IDBDatabase.h b/Source/modules/indexeddb/IDBDatabase.h
index 1a80ba8a5e433f3786ea634cb58a22a1ebd698df..ca4e2d6d8fcfa1bdea52195d6282b7e8255ce06e 100644
--- a/Source/modules/indexeddb/IDBDatabase.h
+++ b/Source/modules/indexeddb/IDBDatabase.h
@@ -113,6 +113,8 @@ public:
 
     static int64_t nextTransactionId();
 
+    void ackReceivedBlobs(const Vector<blink::WebBlobInfo>*);
+
     static const char indexDeletedErrorMessage[];
     static const char isKeyCursorErrorMessage[];
     static const char noKeyOrKeyRangeErrorMessage[];