Add a basic version of Worklet#import.

third_party/WebKit/Source/modules/worklet/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/ScriptWrappable.h"
+#include "core/dom/ActiveDOMObject.h"
+#include "core/frame/csp/ContentSecurityPolicy.h"
+#include "core/workers/WorkerScriptLoader.h"
 #include "modules/worklet/WorkletGlobalScope.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class ExecutionContext;
+class ScriptPromiseResolver;
+class WorkerScriptLoader;
 
-class Worklet final : public GarbageCollectedFinalized<Worklet>, public ScriptWrappable {
+class Worklet final : public GarbageCollectedFinalized<Worklet>, public ScriptWrappable, public ActiveDOMObject {
+    DEFINE_WRAPPERTYPEINFO();
+    USING_GARBAGE_COLLECTED_MIXIN(Worklet);
     WTF_MAKE_NONCOPYABLE(Worklet);
-    DEFINE_WRAPPERTYPEINFO();
 public:
     // The ExecutionContext argument is the parent document of the Worklet. The
     // Worklet inherits the url and userAgent, from the document.
     static Worklet* create(ExecutionContext*);
 
+    ScriptPromise import(ScriptState*, const String& url);
+
+    // ActiveDOMObject
+    void stop() final;
+    bool hasPendingActivity() const final;

[kinuko, 2016/02/12 07:25:45]

nit: this method is now moved to ScriptWrappable as of
https://codereview.chromium.org/1609343002.

A bit unsure how much implementing these are useful?  Worklet is a member of
DOMWindowWorklet so we probably don't need to worry too much about this one's
deleted, and when a parent document is detached this one could probably just
deleted (and then ongoing loaders are cancelled)?  Since worklet runs on the
same script signaling termination doesn't seem very necessary either, but I
could be missing some corner cases...

[ikilpatrick, 2016/02/12 22:59:57]

I'm unsure as well. I had a hunch that this wasn't required, but wasn't sure.

Who would be a good person to check with?

[kinuko, 2016/02/15 04:58:27]

I _think_ we should be fine without implementing hasPendingActivity. We could
explicitly keep the wrapper alive this way to avoid to have it gc'ed and
recreated but we don't seem doing this usually for window members.

cc-ing haraken@ to check with...

[ikilpatrick, 2016/02/16 19:34:14]

Makes sense, removed hasPendingActivity.

I can theoretically also remove stop() as the WorkerScriptLoader destructor will
cancel any pending requests?

+
     DECLARE_TRACE();
 
 private:
     explicit Worklet(ExecutionContext*);
 
+    void onResponse();
+    void onFinished(WorkerScriptLoader*, ScriptPromiseResolver*);
+
     RefPtrWillBeMember<WorkletGlobalScope> m_workletGlobalScope;
+    Vector<RefPtr<WorkerScriptLoader>> m_scriptLoaders;
+    HeapVector<Member<ScriptPromiseResolver>> m_resolvers;
 };
 
 } // namespace blink
 
 #endif // Worklet_h