Disable outputs for tail processing more often

When requesting to delete handlers on the main thread, we exit early
if |rendering_orphan_handlers_| is empty. However,
|DeleteHandlersOnMainThread| will also process
|finished_tail_processing_handlers_|, so we're not processing them in
some cases.

Thus, do an early exit only if both |rendering_orphan_handlers_| and
|finished_tail_processing_handlers_| are empty.  Otherwise, there are
things that need to be deleted but aren't.

Change-Id: If4515a42253dc87aca25c009fccea69b243a06ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1503998
Commit-Queue: Raymond Toy <rtoy@chromium.org>
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637866}

third_party/blink/renderer/modules/webaudio/deferred_task_handler.cc

@@ -332,8 +332,16 @@ void DeferredTaskHandler::AddRenderingOrphanHandler(
 void DeferredTaskHandler::RequestToDeleteHandlersOnMainThread() {
   DCHECK(IsAudioThread());
   AssertGraphOwner();
-  if (rendering_orphan_handlers_.IsEmpty())
+
+  // Quick exit if there are no handlers that need to be deleted so that we
+  // don't unecessarily post a task.  Be onsistent with
+  // |DeleteHandlersOnMainThread()| so we don't accidentally return early when
+  // there are handlers that could be deleted.
+  if (rendering_orphan_handlers_.IsEmpty() &&
+      finished_tail_processing_handlers_.size()) {
     return;
+  }
+
   deletable_orphan_handlers_.AppendVector(rendering_orphan_handlers_);
   rendering_orphan_handlers_.clear();
   PostCrossThreadTask(