[worklets] Introduce ThreadedWorkletMessagingProxy and AnimationWorkletMessagaingProxy.

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

 // 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.
 
 #include "core/workers/Worklet.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptSourceCode.h"
 #include "bindings/core/v8/V8Binding.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/fetch/FetchInitiatorTypeNames.h"
 #include "core/frame/LocalFrame.h"
 #include "core/loader/DocumentLoader.h"
 #include "core/loader/FrameFetchContext.h"
 #include "core/workers/WorkletGlobalScopeProxy.h"
 #include "core/workers/WorkletScriptLoader.h"
 
 namespace blink {
 
 Worklet::Worklet(LocalFrame* frame)
     : ActiveDOMObject(frame->document())
     , m_fetcher(frame->loader().documentLoader()->fetcher())
 {
 }
 
 ScriptPromise Worklet::import(ScriptState* scriptState, const String& url)
 {
+    if (!isInitialized()) {
+        initialize();
+    }
+
     KURL scriptURL = getExecutionContext()->completeURL(url);
     if (!scriptURL.isValid()) {
         return ScriptPromise::rejectWithDOMException(scriptState, DOMException::create(SyntaxError, "'" + url + "' is not a valid URL."));
     }
 
     ResourceRequest resourceRequest(scriptURL);
     resourceRequest.setRequestContext(WebURLRequest::RequestContextScript);
     FetchRequest request(resourceRequest, FetchInitiatorTypeNames::internal);
     ScriptResource* resource = ScriptResource::fetch(request, fetcher());
 
     ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
     if (resource) {
         WorkletScriptLoader* workletLoader = WorkletScriptLoader::create(resolver, this, resource);
         m_scriptLoaders.add(workletLoader);
     } else {
         resolver->reject(DOMException::create(NetworkError));
     }
     return promise;
 }
 
 void Worklet::notifyFinished(WorkletScriptLoader* scriptLoader)
 {
     workletGlobalScopeProxy()->evaluateScript(ScriptSourceCode(scriptLoader->resource()));
     m_scriptLoaders.remove(scriptLoader);
 }
 
 void Worklet::stop()
 {
-    workletGlobalScopeProxy()->terminateWorkletGlobalScope();
+    if (isInitialized()) {
+        workletGlobalScopeProxy()->terminateWorkletGlobalScope();
+    }
+
     for (const auto& scriptLoader : m_scriptLoaders) {
         scriptLoader->cancel();
     }
 }
 
 DEFINE_TRACE(Worklet)
 {
     visitor->trace(m_fetcher);
     visitor->trace(m_scriptLoaders);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace blink