Worklet: Separate Worklet into MainThreadWorklet and ThreadedWorklet

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

+// Copyright 2017 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 ThreadedWorklet_h
+#define ThreadedWorklet_h
+
+#include "core/workers/Worklet.h"
+
+#include "bindings/core/v8/ScriptPromiseResolver.h"
+#include "core/CoreExport.h"
+#include "core/loader/WorkletScriptLoader.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class LocalFrame;
+
+// A ThreadedWorklet is a worklet that runs off the main thread.

[falken, 2017/04/18 03:37:53]

I thought threaded worklet could possibly run on the main thread, no?

[nhiroki, 2017/04/18 04:05:19]

ThreadedWorklet is designed to always run on off-main-thread.

It would be nice if we can unify MainThreadWorklet(GlobalScope) and
ThreadedWorklet(GlobalScope) especially for AnimationWorklet that may run in
both ways, but I'm not sure if it's feasible at this point.

+// TODO(nhiroki): This is a temporary class to keep classic script loading for
+// threaded worklets while module loading is being implemented for main thread
+// worklets. This and MainThreadWorklet will be merged into the base Worklet
+// class once threaded worklets are also ready to use module loading.
+class CORE_EXPORT ThreadedWorklet : public Worklet,
+                                    public WorkletScriptLoader::Client {
+  USING_GARBAGE_COLLECTED_MIXIN(ThreadedWorklet);
+  WTF_MAKE_NONCOPYABLE(ThreadedWorklet);
+
+ public:
+  virtual ~ThreadedWorklet() = default;
+
+  // Worklet
+  ScriptPromise import(ScriptState*, const String& url) final;
+
+  // WorkletScriptLoader::Client
+  void NotifyWorkletScriptLoadingFinished(WorkletScriptLoader*,
+                                          const ScriptSourceCode&) final;
+
+  // ContextLifecycleObserver
+  void ContextDestroyed(ExecutionContext*) final;
+
+  DECLARE_VIRTUAL_TRACE();
+
+ protected:
+  explicit ThreadedWorklet(LocalFrame*);
+
+ private:
+  HeapHashMap<Member<WorkletScriptLoader>, Member<ScriptPromiseResolver>>
+      loader_to_resolver_map_;
+};
+
+}  // namespace blink
+
+#endif  // ThreadedWorklet_h