compositor-worker: Get the thread to run compositor-workers from the Platform.

Source/core/workers/WorkerThread.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 50 matching lines @@
     virtual ~WorkerThread();
 
     // Called on the main thread.
     void start(PassOwnPtr<WorkerThreadStartupData>);
     void terminate();
 
     // Returns the thread this worker runs on. Some implementations can create
     // a new thread on the first call (e.g. shared, dedicated workers), whereas
     // some implementations can use an existing thread that is already being
     // used by other workers (e.g.  compositor workers).
-    virtual WebThreadSupportingGC& backingThread() = 0;
+    virtual WebThread& backingThread() = 0;
 
     virtual void didStartRunLoop();
     virtual void didStopRunLoop();
 
     v8::Isolate* isolate() const { return m_isolate; }
 
     // Can be used to wait for this worker thread to shut down.
     // (This is signaled on the main thread, so it's assumed to be waited on
     // the worker context thread)
     WebWaitableEvent* shutdownEvent() { return m_shutdownEvent.get(); }
@@ skipping 61 matching lines @@
     friend class WorkerMicrotaskRunner;
 
     // Called on the main thread.
     void terminateInternal();
 
     // Called on the worker thread.
     void initialize(PassOwnPtr<WorkerThreadStartupData>);
     void shutdown();
     void performShutdownTask();
     void performIdleWork(double deadlineSeconds);
-    void postDelayedTask(const WebTraceLocation&, PassOwnPtr<ExecutionContextTask>, long long delayMs);
 
     bool m_started;
     bool m_terminated;
     bool m_shutdown;
     MessageQueue<WebThread::Task> m_debuggerMessageQueue;
     OwnPtr<WebThread::TaskObserver> m_microtaskRunner;
 
     RefPtr<WorkerLoaderProxy> m_workerLoaderProxy;
     WorkerReportingProxy& m_workerReportingProxy;
     RawPtr<WebScheduler> m_webScheduler; // Not owned.
 
     RefPtrWillBePersistent<WorkerInspectorController> m_workerInspectorController;
     Mutex m_workerInspectorControllerMutex;
 
     // This lock protects |m_workerGlobalScope|, |m_terminated|, |m_isolate| and |m_microtaskRunner|.
     Mutex m_threadStateMutex;
 
     RefPtrWillBePersistent<WorkerGlobalScope> m_workerGlobalScope;
 
+    OwnPtr<GCSupportForWebThread> m_gcSupport;

[kinuko, 2015/08/10 05:01:21]

I'm a bit confused. Regular workers own WebThreadSupportingGC, which owns
GCSupport and WebThread, while CompositorWorker uses CompositorWorkerManager's
GCSupport and WebThread-- so it doesn't seem we should have the base class own
GCSupport but I'm missing something?

[sadrul, 2015/08/10 06:51:20]

Oh crud. You are right. Sorry, I meant to clean this up before sending off for
review, but forgot.

I have changed the workers to directly create a WebThread instead, and kept the
gc-support management in WorkerThread, so that all the normal workers don't have
to override initializeBackingThread() and shutdownBackingThread() (this
management applies for the normal workers, but compositor-worker overrides this
behaviour; so CompositorWorkerManager still has its own gc-support).

     v8::Isolate* m_isolate;
 
     // Used to signal thread shutdown.
     OwnPtr<WebWaitableEvent> m_shutdownEvent;
 
     // Used to signal thread termination.
     OwnPtr<WebWaitableEvent> m_terminationEvent;
 };
 
 } // namespace blink
 
 #endif // WorkerThread_h