Introduce WorkerBackingThread

third_party/WebKit/Source/core/workers/WorkerThread.h

Index: third_party/WebKit/Source/core/workers/WorkerThread.h
diff --git a/third_party/WebKit/Source/core/workers/WorkerThread.h b/third_party/WebKit/Source/core/workers/WorkerThread.h
index cf6ccda60c48906f732f64b14228702f890c4c55..3b3e4321b9f8235d209462c3b4468d5cd6f742a4 100644
--- a/third_party/WebKit/Source/core/workers/WorkerThread.h
+++ b/third_party/WebKit/Source/core/workers/WorkerThread.h
@@ -44,6 +44,7 @@ namespace blink {
 
 class InspectorTaskRunner;
 class WaitableEvent;
+class WorkerBackingThread;
 class WorkerGlobalScope;
 class WorkerInspectorController;
 class WorkerMicrotaskRunner;
@@ -64,16 +65,8 @@ public:
     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 void didStartWorkerThread();
-    virtual void willStopWorkerThread();
-
-    v8::Isolate* isolate() const { return m_isolate; }
+    WorkerBackingThread& workerBackingThread();
+    v8::Isolate* isolate() const;
 
     // 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
@@ -115,24 +108,13 @@ public:
     PlatformThreadId platformThreadId();
 
 protected:
-    WorkerThread(PassRefPtr<WorkerLoaderProxy>, WorkerReportingProxy&);
+    WorkerThread(PassRefPtr<WorkerLoaderProxy>, WorkerReportingProxy&, PassRefPtr<WorkerBackingThread>);
 
     // Factory method for creating a new worker context for the thread.
     virtual PassRefPtrWillBeRawPtr<WorkerGlobalScope> createWorkerGlobalScope(PassOwnPtr<WorkerThreadStartupData>) = 0;
 
     virtual void postInitialize() { }
 
-    // Both of these methods are called in the worker thread.
-    virtual void initializeBackingThread();
-    virtual void shutdownBackingThread();
-
-    virtual v8::Isolate* initializeIsolate();
-    virtual void willDestroyIsolate();
-    virtual void destroyIsolate();
-
-    // Can be called either on main or worker thread.
-    virtual void terminateV8Execution();
-
 private:
     friend class WorkerMicrotaskRunner;
 
@@ -162,12 +144,14 @@ private:
     WorkerReportingProxy& m_workerReportingProxy;
     RawPtr<WebScheduler> m_webScheduler; // Not owned.
 
-    // This lock protects |m_workerGlobalScope|, |m_terminated|, |m_shutdown|, |m_isolate|, |m_runningDebuggerTask|, |m_shouldTerminateV8Execution| and |m_microtaskRunner|.
+    // This lock protects |m_workerGlobalScope|, |m_terminated|, |m_shutdown|,
+    // |m_runningDebuggerTask|, |m_shouldTerminateV8Execution| and
+    // |m_microtaskRunner|.
     Mutex m_threadStateMutex;
 
     RefPtrWillBePersistent<WorkerGlobalScope> m_workerGlobalScope;
 
-    v8::Isolate* m_isolate;
+    RefPtr<WorkerBackingThread> m_workerBackingThread;
 
     // Used to signal thread shutdown.
     OwnPtr<WaitableEvent> m_shutdownEvent;