Change the return type of WTF::bind() to |OwnPtr<Function>|

Source/core/workers/WorkerThread.cpp

Index: Source/core/workers/WorkerThread.cpp
diff --git a/Source/core/workers/WorkerThread.cpp b/Source/core/workers/WorkerThread.cpp
index 6a0ad514baf928787325d3b33eb458c05488f8c3..23e90e4a8af7e59184c019c9151b355277cd4ec7 100644
--- a/Source/core/workers/WorkerThread.cpp
+++ b/Source/core/workers/WorkerThread.cpp
@@ -90,7 +90,7 @@ unsigned WorkerThread::workerThreadCount()
 class WorkerThreadCancelableTask final : public ExecutionContextTask {
     WTF_MAKE_NONCOPYABLE(WorkerThreadCancelableTask); WTF_MAKE_FAST_ALLOCATED;
 public:
-    static PassOwnPtr<WorkerThreadCancelableTask> create(const Closure& closure)
+    static PassOwnPtr<WorkerThreadCancelableTask> create(PassOwnPtr<Closure> closure)
     {
         return adoptPtr(new WorkerThreadCancelableTask(closure));
     }
@@ -98,18 +98,18 @@ public:
     virtual void performTask(ExecutionContext*) override
     {
         if (!m_taskCanceled)
-            m_closure();
+            (*m_closure)();
     }
 
     void cancelTask() { m_taskCanceled = true; }
 
 private:
-    explicit WorkerThreadCancelableTask(const Closure& closure)
+    explicit WorkerThreadCancelableTask(PassOwnPtr<Closure> closure)
     : m_closure(closure)
     , m_taskCanceled(false)
     { }
 
-    Closure m_closure;
+    OwnPtr<Closure> m_closure;
     bool m_taskCanceled;
 };