Support CrossThreadWeakPersistent PostTask on per thread heap enabled thread

third_party/WebKit/Source/platform/heap/Persistent.h

Index: third_party/WebKit/Source/platform/heap/Persistent.h
diff --git a/third_party/WebKit/Source/platform/heap/Persistent.h b/third_party/WebKit/Source/platform/heap/Persistent.h
index 37399f545ca475db1e18cd29ce91cdf00fed7e81..baf4856b2492d239263ed0dbd995095c747ce6fc 100644
--- a/third_party/WebKit/Source/platform/heap/Persistent.h
+++ b/third_party/WebKit/Source/platform/heap/Persistent.h
@@ -766,6 +766,15 @@ struct IsWeakReceiver<blink::WeakPersistent<T>> : std::true_type {};
 template <typename T>
 struct IsWeakReceiver<blink::CrossThreadWeakPersistent<T>> : std::true_type {};
 
+template <typename T>
+struct BindUnwrapTraits<blink::CrossThreadWeakPersistent<T>> {
+    static blink::CrossThreadPersistent<T> Unwrap(const blink::CrossThreadWeakPersistent<T>& wrapped)
+    {
+        blink::CrossThreadPersistentRegion::LockScope persistentLock(blink::ProcessHeap::crossThreadPersistentRegion());
+        return blink::CrossThreadPersistent<T>(wrapped.get());
+    }
+};
+
 }
 
 #endif // Persistent_h