IndexedDB: Optimize IDBCursor.advance() if it occurs within prefetched range

content/child/indexed_db/proxy_webidbcursor_impl.h

Index: content/child/indexed_db/proxy_webidbcursor_impl.h
diff --git a/content/child/indexed_db/proxy_webidbcursor_impl.h b/content/child/indexed_db/proxy_webidbcursor_impl.h
index c92b090b5b730669cfc83507399ad88fd9729680..467f6467b5f43bb07ecac24e9c3465819942799e 100644
--- a/content/child/indexed_db/proxy_webidbcursor_impl.h
+++ b/content/child/indexed_db/proxy_webidbcursor_impl.h
@@ -41,11 +41,13 @@ class CONTENT_EXPORT RendererWebIDBCursorImpl
                        const std::vector<IndexedDBKey>& primary_keys,
                        const std::vector<blink::WebData>& values);
 
+  void CachedAdvance(unsigned long count, blink::WebIDBCallbacks* callbacks);
   void CachedContinue(blink::WebIDBCallbacks* callbacks);
   void ResetPrefetchCache();
 
  private:
   FRIEND_TEST_ALL_PREFIXES(RendererWebIDBCursorImplTest, PrefetchTest);
+  FRIEND_TEST_ALL_PREFIXES(RendererWebIDBCursorImplTest, AdvancePrefetchTest);
 
   int32 ipc_cursor_id_;