Speed up IDB by trimming down the BlobChangeMaps. Check to see if we need each

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 6720ee9b5d0c40acbcad97aad85775a8b16f5777..46e1e0646becc640e7256d7ab1d8f48feb46d022 100644
--- a/content/browser/indexed_db/indexed_db_backing_store.h
+++ b/content/browser/indexed_db/indexed_db_backing_store.h
@@ -407,6 +407,12 @@ class CONTENT_EXPORT IndexedDBBackingStore
       backing_store_ = NULL;
       transaction_ = NULL;
     }
+    leveldb::Status PutBlobInfoIfNeeded(
+        int64 database_id,
+        int64 object_store_id,
+        const std::string& object_store_data_key,
+        std::vector<IndexedDBBlobInfo>*,
+        ScopedVector<webkit_blob::BlobDataHandle>* handles);
     void PutBlobInfo(int64 database_id,
                      int64 object_store_id,
                      const std::string& object_store_data_key,