Introduce ThreadableLoadingContext: make threaded loading code one step away from Document

third_party/WebKit/Source/core/workers/ThreadedMessagingProxyBase.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 ThreadedMessagingProxyBase_h
 #define ThreadedMessagingProxyBase_h
 
 #include "core/CoreExport.h"
 #include "core/frame/UseCounter.h"
 #include "core/inspector/ConsoleTypes.h"
@@ skipping 67 matching lines @@
   bool isParentContextThread() const;
 
   // WorkerLoaderProxyProvider
   // These methods are called on different threads to schedule loading
   // requests and to send callbacks back to WorkerGlobalScope.
   void postTaskToLoader(const WebTraceLocation&,
                         std::unique_ptr<WTF::CrossThreadClosure>) override;
   void postTaskToWorkerGlobalScope(
       const WebTraceLocation&,
       std::unique_ptr<WTF::CrossThreadClosure>) override;
-  ExecutionContext* getLoaderExecutionContext() override;
+  ThreadableLoadingContext* getThreadableLoadingContext() override;
 
  private:
   friend class InProcessWorkerMessagingProxyForTest;
   friend class ThreadedWorkletMessagingProxyForTest;
 
   void parentObjectDestroyedInternal();
 
   Persistent<ExecutionContext> m_executionContext;
+  Persistent<ThreadableLoadingContext> m_loadingContext;
   Persistent<WorkerInspectorProxy> m_workerInspectorProxy;
   // Accessed cross-thread when worker thread posts tasks to the parent.
   CrossThreadPersistent<ParentFrameTaskRunners> m_parentFrameTaskRunners;
 
   std::unique_ptr<WorkerThread> m_workerThread;
 
   RefPtr<WorkerLoaderProxy> m_loaderProxy;
 
   bool m_mayBeDestroyed;
   bool m_askedToTerminate;
 };
 
 }  // namespace blink
 
 #endif  // ThreadedMessagingProxyBase_h