Disallow cross-thread Persistent<> read access.

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"
+#include "core/workers/ParentFrameTaskRunners.h"
 #include "core/workers/WorkerLoaderProxy.h"
 #include "wtf/Forward.h"
 
 namespace blink {
 
 class ExecutionContext;
-class ParentFrameTaskRunners;
 class SourceLocation;
 class WorkerInspectorProxy;
 class WorkerLoaderProxy;
 class WorkerThread;
 class WorkerThreadStartupData;
 
 class CORE_EXPORT ThreadedMessagingProxyBase
     : private WorkerLoaderProxyProvider {
  public:
   void terminateGlobalScope();
 
   virtual void workerThreadCreated();
 
   // This method should be called in the destructor of the object which
   // initially created it. This object could either be a Worker or a Worklet.
   virtual void parentObjectDestroyed();
 
   void countFeature(UseCounter::Feature);
   void countDeprecation(UseCounter::Feature);
 
   void reportConsoleMessage(MessageSource,
                             MessageLevel,
                             const String& message,
                             std::unique_ptr<SourceLocation>);
   void postMessageToPageInspector(const String&);
 
   // 'virtual' for testing.
   virtual void workerThreadTerminated();
 
+  // Accessed from both the parent thread and the worker.
   ExecutionContext* getExecutionContext() const {
     return m_executionContext.get();
   }
 
+  // Accessed from both the parent thread and the worker.
   ParentFrameTaskRunners* getParentFrameTaskRunners() {
     return m_parentFrameTaskRunners.get();
   }
 
   // Number of live messaging proxies, used by leak detection.
   static int proxyCount();
 
  protected:
   ThreadedMessagingProxyBase(ExecutionContext*);
   ~ThreadedMessagingProxyBase() override;
 
   void initializeWorkerThread(std::unique_ptr<WorkerThreadStartupData>);
   virtual std::unique_ptr<WorkerThread> createWorkerThread(
       double originTime) = 0;
 
   WorkerThread* workerThread() const { return m_workerThread.get(); }
 
   bool askedToTerminate() const { return m_askedToTerminate; }
 
   PassRefPtr<WorkerLoaderProxy> loaderProxy() { return m_loaderProxy; }
-  WorkerInspectorProxy* workerInspectorProxy() {
+  WorkerInspectorProxy* workerInspectorProxy() const {
     return m_workerInspectorProxy.get();
   }
 
   // Returns true if this is called on the parent context thread.
   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<ExecutionContextTask>) override;
   void postTaskToWorkerGlobalScope(
       const WebTraceLocation&,
       std::unique_ptr<WTF::CrossThreadClosure>) override;
 
  private:
   friend class InProcessWorkerMessagingProxyForTest;
   friend class ThreadedWorkletMessagingProxyForTest;
 
   void parentObjectDestroyedInternal();
 
-  Persistent<ExecutionContext> m_executionContext;
+  // Accessed cross-thread when worker thread posts tasks to the parent.
+  CrossThreadPersistent<ExecutionContext> m_executionContext;

[haraken, 2017/02/20 23:57:18]

Ditto.

   Persistent<WorkerInspectorProxy> m_workerInspectorProxy;
-  Persistent<ParentFrameTaskRunners> m_parentFrameTaskRunners;
+  // 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