Remove unused method declaration

This overload of IDBRequest::EnqueueResponse was only used for devtools,
which no longer uses it as of [1].

The implementation of this method was removed here [2].

[1] https://crbug.com/992958
[2] https://crrev.com/c/2563872

Bug: N/A
Change-Id: Iacf15ee27b7505c7fba44d00f675a38bf7125f25
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2621954
Auto-Submit: Austin Sullivan <asully@chromium.org>
Commit-Queue: enne <enne@chromium.org>
Reviewed-by: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842680}

third_party/blink/renderer/modules/indexeddb/idb_request.h

@@ -276,10 +276,6 @@ class MODULES_EXPORT IDBRequest : public EventTargetWithInlineData,
       mojo::PendingReceiver<mojom::blink::IDBDatabaseGetAllResultSink>
           receiver);
 
-  // Only used in webkitGetDatabaseNames(), which is deprecated and hopefully
-  // going away soon.
-  void EnqueueResponse(const Vector<String>&);
-
   // Only IDBOpenDBRequest instances should receive these:
   virtual void EnqueueBlocked(int64_t old_version) { NOTREACHED(); }
   virtual void EnqueueUpgradeNeeded(int64_t old_version,