AudioWorkletObjectProxy::DidEvaluateModuleScript to post a loading task.

We wish to prioritize loading and compositing tasks till FCP, but
that changes the order in which the task posted by
AudioWorkletObjectProxy::DidEvaluateModuleScript runs in relation to
other loading tasks (it's called by
WorkletModuleTreeClient::NotifyModuleTreeLoadFinished).

Changing this task to be TaskType::kInternalLoad preserves the
original order with the new scheduler policy.

Bug: 971191
Change-Id: I1d80a9c7dd7e9c97b7303b087506caa9e51981d8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1819255
Commit-Queue: Alex Clarke <alexclarke@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#699684}

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

@@ -41,8 +41,12 @@ void AudioWorkletObjectProxy::DidEvaluateModuleScript(bool success) {
   if (processor_info_list->size() == 0)
     return;
 
+  // This method is called by a loading task which calls
+  // WorkletModuleTreeClient::NotifyModuleTreeLoadFinished and
+  // SynchronizeWorkletProcessorInfoList needs to run in FIFO order with other
+  // loading tasks.
   PostCrossThreadTask(
-      *GetParentExecutionContextTaskRunners()->Get(TaskType::kInternalMedia),
+      *GetParentExecutionContextTaskRunners()->Get(TaskType::kInternalLoading),
       FROM_HERE,
       CrossThreadBindOnce(
           &AudioWorkletMessagingProxy::SynchronizeWorkletProcessorInfoList,