Converting DedicatedWorker from EagerSweeping to PreFinalizer

Pre-finalizer performs:
1) Inform context_proxy_ that parent is destroyed
2) Cancel requests to classic_script_loader_
3) Reset uniqueptr to factory_client_

Bug: 981043
Change-Id: I425513bcc91d7d8676d575d302be85c9ca114cf4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1690584Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#675716}

third_party/blink/renderer/core/workers/dedicated_worker.cc

@@ -161,9 +161,12 @@ DedicatedWorker::DedicatedWorker(ExecutionContext* context,
           context->Fetcher()->GetProperties().GetFetchClientSettingsObject());
 }
 
-DedicatedWorker::~DedicatedWorker() {
+DedicatedWorker::~DedicatedWorker() = default;
+
+void DedicatedWorker::Dispose() {
   DCHECK(!GetExecutionContext() || GetExecutionContext()->IsContextThread());
   context_proxy_->ParentObjectDestroyed();
+  factory_client_.reset();
 }
 
 void DedicatedWorker::postMessage(ScriptState* script_state,

third_party/blink/renderer/core/workers/dedicated_worker.h

@@ -70,9 +70,9 @@ class CORE_EXPORT DedicatedWorker final
       public WebDedicatedWorker {
   DEFINE_WRAPPERTYPEINFO();
   USING_GARBAGE_COLLECTED_MIXIN(DedicatedWorker);
-  // Eager finalization is needed to notify the parent object destruction of the
+  // Pre-finalization is needed to notify the parent object destruction of the
   // GC-managed messaging proxy and to initiate worker termination.
-  EAGERLY_FINALIZE();
+  USING_PRE_FINALIZER(DedicatedWorker, Dispose);
 
  public:
   static DedicatedWorker* Create(ExecutionContext*,
@@ -85,6 +85,8 @@ class CORE_EXPORT DedicatedWorker final
                   const WorkerOptions*);
   ~DedicatedWorker() override;
 
+  void Dispose();
+
   void postMessage(ScriptState*,
                    const ScriptValue& message,
                    Vector<ScriptValue>& transfer,