Worklet: Separate Worklet into MainThreadWorklet and ThreadedWorklet

third_party/WebKit/Source/core/workers/Worklet.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef Worklet_h
 #define Worklet_h
 
 #include "bindings/core/v8/ScriptPromise.h"
-#include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/CoreExport.h"
 #include "core/dom/ContextLifecycleObserver.h"
-#include "core/loader/WorkletScriptLoader.h"
 #include "platform/heap/Handle.h"
-#include "platform/loader/fetch/ResourceFetcher.h"
 
 namespace blink {
 
 class LocalFrame;
 class WorkletGlobalScopeProxy;
 
+// This is the base implementation of Worklet interface defined in the spec:
+// https://drafts.css-houdini.org/worklets/#worklet
+// Although some worklets run off the main thread, this must be created and
+// destroyed on the main thread.
 class CORE_EXPORT Worklet : public GarbageCollectedFinalized<Worklet>,
-                            public WorkletScriptLoader::Client,
                             public ScriptWrappable,
                             public ContextLifecycleObserver {
   DEFINE_WRAPPERTYPEINFO();
   USING_GARBAGE_COLLECTED_MIXIN(Worklet);
   WTF_MAKE_NONCOPYABLE(Worklet);
 
  public:
   virtual ~Worklet() = default;
 
   virtual void Initialize() {}
   virtual bool IsInitialized() const { return true; }
 
+  // Worklet.idl
+  // import() imports ES6 module scripts.
+  virtual ScriptPromise import(ScriptState*, const String& url) = 0;
+
+  // Returns a proxy to WorkletGlobalScope on the context thread.
   virtual WorkletGlobalScopeProxy* GetWorkletGlobalScopeProxy() const = 0;
 
-  // Worklet
-  ScriptPromise import(ScriptState*, const String& url);
-
-  // WorkletScriptLoader::Client
-  void NotifyWorkletScriptLoadingFinished(WorkletScriptLoader*,
-                                          const ScriptSourceCode&) final;
-
   // ContextLifecycleObserver
-  void ContextDestroyed(ExecutionContext*) final;
+  virtual void ContextDestroyed(ExecutionContext*);
 
   DECLARE_VIRTUAL_TRACE();
 
  protected:
   // The Worklet inherits the url and userAgent from the frame->document().
   explicit Worklet(LocalFrame*);
 
- private:
   Member<LocalFrame> frame_;
-  HeapHashMap<Member<WorkletScriptLoader>, Member<ScriptPromiseResolver>>
-      loader_and_resolvers_;
 };
 
 }  // namespace blink
 
 #endif  // Worklet_h