Rewrite scoped_ptr<T>(NULL) to use the default ctor in cc/.

cc/layers/tiled_layer_unittest.cc

Index: cc/layers/tiled_layer_unittest.cc
diff --git a/cc/layers/tiled_layer_unittest.cc b/cc/layers/tiled_layer_unittest.cc
index 819a8743ae1567e88712511e7fa780380e9c6620..086b3afaa500bf62ccd4978b227ce7e7884d87fa 100644
--- a/cc/layers/tiled_layer_unittest.cc
+++ b/cc/layers/tiled_layer_unittest.cc
@@ -56,9 +56,8 @@ class TiledLayerTest : public testing::Test {
   }
 
   virtual void SetUp() {
-    layer_tree_host_ = LayerTreeHost::Create(&fake_layer_impl_tree_host_client_,
-                                             settings_,
-                                             scoped_ptr<Thread>(NULL));
+    layer_tree_host_ = LayerTreeHost::Create(
+        &fake_layer_impl_tree_host_client_, settings_, scoped_ptr<Thread>());
     proxy_ = layer_tree_host_->proxy();
     resource_manager_ = PrioritizedResourceManager::Create(proxy_);
     layer_tree_host_->InitializeOutputSurfaceIfNeeded();