Implement WebThreadSupportingGC, which wraps a WebThread attached to Oilpan's GC

Source/platform/WebThreadSupportingGC.h

+// Copyright 2014 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 WebThreadSupportingGC_h
+#define WebThreadSupportingGC_h
+
+#include "platform/heap/glue/MessageLoopInterruptor.h"
+#include "platform/heap/glue/PendingGCRunner.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebThread.h"
+#include "wtf/Noncopyable.h"
+#include "wtf/OwnPtr.h"
+#include "wtf/PassOwnPtr.h"
+
+namespace blink {
+
+// WebThreadSupportingGC wraps a WebThread and adds support for attaching
+// to and detaching from the Blink GC infrastructure. The attachGC method
+// must be called during initialization on the WebThread and before the
+// thread allocates any objects managed by the Blink GC. The detach GC
+// method must be called on the WebThread during shutdown when the thread
+// no longer needs to access objects managed by the Blink GC.
+class PLATFORM_EXPORT WebThreadSupportingGC {
+    WTF_MAKE_NONCOPYABLE(WebThreadSupportingGC);
+public:
+    static PassOwnPtr<WebThreadSupportingGC> create(const char*);
+
+    void postTask(WebThread::Task* task)
+    {
+        m_thread->postTask(task);
+    }
+
+    void postDelayedTask(WebThread::Task* task, long long delayMs)
+    {
+        m_thread->postDelayedTask(task, delayMs);
+    }
+
+    bool isCurrentThread() const
+    {
+        return m_thread->isCurrentThread();
+    }
+
+    void addTaskObserver(WebThread::TaskObserver* observer)
+    {
+        m_thread->addTaskObserver(observer);
+    }
+
+    void removeTaskObserver(WebThread::TaskObserver* observer)
+    {
+        m_thread->removeTaskObserver(observer);
+    }
+
+    void enterRunLoop()
+    {
+        m_thread->enterRunLoop();
+    }
+
+    void exitRunLoop()
+    {
+        m_thread->exitRunLoop();
+    }
+
+    void attachGC();
+    void detachGC();
+
+    WebThread& platformThread() const
+    {
+        ASSERT(m_thread);
+        return *m_thread;
+    }
+
+private:
+    explicit WebThreadSupportingGC(const char*);
+
+    OwnPtr<PendingGCRunner> m_pendingGCRunner;
+    OwnPtr<MessageLoopInterruptor> m_messageLoopInterruptor;
+
+    // FIXME: This has to be last because of crbug.com/401397.
+    // A WorkerThread might get deleted before it had a chance to properly
+    // shut down. By deleting the WebThread first, we can guarantee that
+    // no pending tasks on the thread might want to access any of the other
+    // members during the WorkerThread's destruction.
+    OwnPtr<WebThread> m_thread;
+};
+
+}
+
+#endif